Docstoc

Physical layer specification Link_Network protocol specification

Document Sample
Physical layer specification Link_Network protocol specification Powered By Docstoc
					Physical layer specification          A




Link&Network protocol specification   B
2
UNI-TELWAY reference manual                     Contents
Physical layer specification                    Section A
                                                            A



Chapter                                             Page
1. Introduction                                         3


2. UNI-TELWAY transmission line specification           5


      2.1 Data transmission                             5


      2.2 Line terminator                               6


      2.3 Cable characteristics                         6
          2.3.1 Mechanical characteristics:             6
          2.3.2 Electrical characteristics:             6

      2.4 Performances                                  7
          2.4.1 Stations number                         7
          2.4.2 Speed                                   7
          2.4.3 Line length                             7

3. UNI-TELWAY interface specification                   9


      3.1 principles                                    9


      3.2 Exchanged signals                             9


      3.3 Signals coding rules                          9
          3.3.1 Addressing principles                   9
          3.3.2 Address coding rule                     9
          3.3.3 Parity coding rule                     10
          3.3.4 Signal /UTW                            10
          3.3.5 Data and shield signals                10
          3.3.6 Particular conventions                 10
          3.3.7 Example                                11

      3.4 Isolation                                    12
          3.4.1 Principles                             12
          3.4.2 Isolation values                       13
          3.4.3 Interference proofing                  13

      3.5 Connector                                    14
          3.5.1 Device side :                          14
          3.5.2 Line side                              14

                                                        1
    UNI-TELWAY reference manual                 Contents
A   Physical layer specification                Section A




    Chapter                                         Page


    4. Line tool characteristics                       15


           4.1 Principles                              15


           4.2 Line emitter/receiver                   15


           4.3 Conventions                             16


           4.4 Line polarization                       16


    5. Connection method and accessories               19


           5.1 Generalities                            19


           5.2 Two-channels subscriber socket          19


           5.3 Passive T-junction box                  20


           5.4 Bus connecting cable                    20


           5.5 Standard junction box                   20


           5.6 Line topology                           21
               5.6.1 Derivation connection             21
               5.6.2 Chaining connection               22
               5.6.3 Mixed connections                 22




    2
                                                                      Chapter 1
1
                                                                                             A
                                                                      1. Introduction


The devices communicating with UNI-TELWAY will be connected to an UNI-
TELWAY transmission line.

This serial shielded transmission line is bi-directional and multi-points. The
transmission is in half duplex mode

Any device connected should manage the full UNI-TELWAY protocol and a
physical address in range 0 to 31 (decimal).

At the physical level, we should distinguish between two types of devices :
•    The STANDARD devices using strictly the standard connection interface
     defined in this document
•    The COMPATIBLE devices which include an electrical interface compatible
     with this specification but not fully conformant to it (other cable type, other
     address management, non isolated device…)

The aim of this document is to:
•   Provide the electrical and physical specification of the UNI-TELWAY
    transmission line
•   Provide the electrical and physical specification of the UNI-TELWAY
    connecting interface.
•   Specify the medium access part required to connect the device to the
    network.
•   Specify the coding rules of the device address and associated parity.
•   Specify the device connection method (standard or not).

The UNI-TELWAY link schema can be shown as follows:

                                                     UNI-TELWAY transmission line

                                                                           UNI-TELWAY
                                                                             interface
                                                Specific adapter
                   Standard device                                             device
                                                 Non-standard                  s
                                                   device


                        Station                      Station




It is made of:
•     The transmission line with terminators at both ends


                                                                                         3
A

    •   Several stations made of
        •  Devices conformant to the UNI-TELWAY interface
        •  Devices non-conformant and connected via a specific adapter.




    4
                                                                 Chapter 2
                                                                                  A
                                2. UNI-TELWAY transmission line specification

2.1 Data transmission
The data transmission is in differential mode on a twisted pair cable. The data
signals, called D(A) and D(B) should have electrical characteristics conformant
to the EIA RS 485 norm (respectively section A/A’ and B/B’ of this norm).

The proper emission/reception behavior requires the inter-connection of the
“common parts” of each station connected (RS 485 norm, section C/C’). This
voltage reference called 0VL will be transported through a second twisted pair
cable.

Finally, both cables should be shielded for EMC protection (Signal called
BLIND).

Signals definition:

           Signal                 Definition
         D(A)          Data (A/A’ of RS485)
         D(B)          Data (B/B’ of RS485)
         0VL           Common (C/C’ of RS485)
         BLIND         Shield

RS 485 conventions recall

                D(A)-D(B) voltage               Line logical state
         D(A)-D(B) < -200 mV                 Binary state “1” (MARK)
         D(B)-D(B) > 200 mV                  Binary state “0” (SPACE)
         -200 mV < D(B)-D(B) < 200 mV        Unspecified state

UNI-TELWAY transmission line:

                                                    D(B)
                                                    D(A)
                                                    0VL
                                                    0VL
                                                    BLIND

                                D(B)
                            D(A)
                          0VL
                                       towards UNI-TELWAY interface
                      0VL
                  BLIND


                                                                             5
A

    2.2 Line terminator
    The data transmission cable must be terminated at both ends with the following
    RC circuit:
                                                  D(A)
                        1 nF (50v)



                 120 Ohms (1/4 W)

                                                       D(B)

    This electrical adaptation limits the signal reflections for the usual UNI-TELWAY
    transmission speeds (up to 19200 baud).
    Moreover, it polarizes the line, setting it in high impedance status on a static
    point of view (see section 4.4)

    2.3 Cable characteristics
    The standard UNI-TELWAY cable recommended by Schneider Automation is a
    RS485 doubled shielded twisted pair referenced TSX CSA 100 (length 100 m),
    TSX CSA 200 (200 m) and TSX CSA 500 (500 m)

    2.3.1 Mechanical characteristics:
    Colors                           white-blue, white-red
    Inner copper wire                7x0.2mm (diameter 0.6 mm)
    PVC isolation                    70 degrees, 0.3mm thick (diameter 1.2mm)
    Assembling                       in pairs (diameter 2.4mm)
    Copper shielding                 40x0.15mm (diameter 2.7mm)


    2.3.2 Electrical characteristics:
    Wire linear resistance:    85 ohms/km
    Shield linear resistance:  12 ohms/km
    Loss (adapted line):       13 dB/km from 0 to 20khz, then 1/f when greater
                               (example: 16 dB/km at 100 kHz).
    Linear capacity between conductor of a same pair: 100 pF/m




    6
                            UNI-TELWAY transmission line specification       2    A
2.4 Performances
2.4.1 Stations number
Each device connected to the transmission line is seen as an electrical load on
that line. It is due to the medium access components and the polarization
resistors of each station.
As the medium access components should be conformant with the RS-485
electrical specification, and the polarization resistor values are fixed, it is
possible to determine the stations maximum number on a single UNI-TELWAY
line.

The maximum number has been set to 28.

2.4.2 Speed
The standard transmission speed is set at 9600 baud.
However, it can be modified up to 19200 baud.

2.4.3 Line length
The maximum length of the line is mostly function of the cable quality.
With the cable we recommend, the maximum length of the main wire is around
1000 meters.

The length of each derivation should be limited to 20 meters.
With twisted pair cable of greater section, the maximum length can be greater,
provided that you still follow the RS-485 norm recommendations.




                                                                             7
A




    8
                                                                        Chapter 3
                                                                                           A
                                           3. UNI-TELWAY interface specification

3.1 principles
The UNI-TELWAY interface is
defined as the junction                                 Standard
between the line transmission                            device
and the device connected to
it.                                                                           UNI-TELWAY
This interface defines the                                                    interface
                                                                   Standard
connector (cable side, device
                                                               UNITELWA
side) and the electrical signals             UNI-TELWAY         Y connector
exchanged.                              transmission cable
                                            (main frame or
                                                derivation)



3.2 Exchanged signals
The exchanged signals are of four types:
•   Address signals : N0 to N4, PARITY and COMMON
•   Control signal /UTW
•   Data signals : D(A), D(B) and 0VL
•   Shield BLIND

3.3 Signals coding rules
3.3.1 Addressing principles
The device address should be comprised in range [0.31] (decimal). It will be
coded by wiring some N0 to N4 signals to COMMON.
A PARITY signal is associated to the address, by wiring (or not) this signal to
COMMON.
The connected device should realize the reading and processing of those signals.

3.3.2 Address coding rule
The address is the sum of the N(x) signals weight.

If N(x) is unconnected, N(x) = 2x
If N(x) is wired to COMMON, N(x) = 0.


Signal wired to COMMON         N4    N3          N2       N1       N0
Weight in decimal              16    8           4        2        1




                                                                                       9
A


    3.3.3 Parity coding rule
    The parity associated to the address is coded by wiring the PARITY signal to
    COMMON or not, so that the total number of signals wired to COMMON is odd.

    3.3.4 Signal /UTW
    This signal, seen as an input on the device (as the address and parity signals)
    tells whether the device supports the UNI-TELWAY protocol or not.

    /UTW wired to COMMON (logical “0”):               UNI-TELWAY protocol
    /UTW unconnected (logical “1”):                   other

    3.3.5 Data and shield signals
    The naming conventions for the data signals are identical to the conventions
    used for the transmission line (D(A), D(B), 0VL).
    The BLIND transmission line signal becomes GROUND local protection. The
    metallic main frame of the device connector should ensure the link between the
    two signals.

    3.3.6 Particular conventions
    In case of direct device connection to the UNI-TELWAY transmission line in order
    to make a derivation through screw terminal block for example, it is necessary to
    follow some rules about the respective position of the signals:

                   Reading direction
                   Contacts number          1    2        3        4        5
                   Screw terminal block

                   Signal name            BLIND 0VL 0VL D(A) D(B)

    When the addressing operation will be realized with straps or switches, the
    addressing signals position should be as follows:

                   Reading direction
                                          PF
                                           f




                           Parity         N4    N3   N2       N1       N0




    10
                                        UNI-TELWAY interface specification   3    A
3.3.7 Example


Address: 14.


note
/UTW signal set to 0 (UNI-TELWAY protocol).



            UNI-TELWAY standard interface
                                                                    VCC


                                                    PULL UPS




            4                          4
                        Parity
           11                          11
                          N4

           3                           3
                          N3
                                                                   Logical
           10
                                       10                           inputs
                          N2
           2
                                       2
                          N1
           9                           9
                          N0
           12                          12
                        /UTW

            5                          5
                        COMMON



       line connector            device connector

                                                                   GROUND




                                                                             11
A

        3.4 Isolation
        We call PE (Protective Earth) the shielding conductor, connected to local earth of
        the device.
        We call FE (Functional Earth) the electrical zero volt of the device secondary.
        We call 0VL (line zero volt) the potential difference of the transmission line.
                                                                                          UNI-
                                                                e                       TELWAY
                                                                                          line
                                     Logic         d                          D
                                                                Isolation

                               Vcc       GND                        c
    a
                  Power
                  supply                     b         Power
                                                       supply
                           z
                                                                                        BLIND
        PE                             FE                               0VL




        a = 220V (for example)
        b = 12V (for example)
        c = 5V (for example)
        d = RX, TX, ENABLE signals
        D = D(A) and D(B)
        e = address signals


        3.4.1 Principles
        In order to improve the EMC immunity on the line, the D(A), D(B) and 0VL should
        be isolated from the device logical components.
        This isolation is not required on the address, control (/UTW) and common
        signals.

        Generally, the isolation is ensured by using an isolated power supply
        specifically for the line emitter/receiver and by isolating the data signals by opto-
        couplers.

        It can be seen as a functional isolation, dedicated to limiting the propagation of
        line disturbances towards the device. There won't be any security isolation for
        the device itself or the persons.



        12
                                        UNI-TELWAY interface specification          3    A

In order to be kept stable, the 0VL is linked to local earth (PE) by a RC circuit like
:

                                                                      0VL

         22 nF 630V                            10 Moms




3.4.2 Isolation values
Two cases can occur :
•  No security isolation between PE and FE, functional isolation only. In this
   case, a minimum functional isolation VL=350 Veff (50Hz, 1 minute) or 500
   Vdc between logical zero volt (FE) and transmission line zero volt (0VL). This
   is the minimum isolation that should provide the separate power supply.
   The D(A) and D(B) signals should be functionally isolated of the signals
   coming from the device with the same VL minimum value.
•  The security isolation between PE and FE exists on the device. The Z
   impedance is then very high and the voltage isolation values greater than
   Vs=500 or 1000V. In this case, a security isolation between the logical zero
   volt (FE) and the line zero volt (0VL) is required with a minimum equal to Vs.

CAUTION : in this latter case, the security isolation may be limited by the
isolation distances of the terminal block connectors (see figures below).

3.4.3 Interference proofing
The aim is to be conformant to IEC 801 norm. (IEC = International Electro-
technical Commission).
Respecting that norm will be function of the cable quality, connector quality, the
shielding continuity and the various earth connections.

It is preferable to include a protection cover on the device connector described
above when not used.




                                                                                   13
A

    3.5 Connector
    The UNI-TELWAY interface connector is a metallic SUBD 15 points, female on
    the device side, male on the transmission line side.
    The pins description is as follows :

    3.5.1 Device side :


                      0VL       D(A)           common      parity   N3        N1
                                                                                                1
                  8
                          15
                                                                                        9
                           0VL       D(B)           /UTW       N4        N2        N0


    The connector main frame should be connected to PE
    The crossed pins are reserved.

    3.5.2 Line side


                               N1        N3    parity common             D(A)      0VL
                                                                                            8
              1
                      9
                                                                                  15
                          N0        N2        N4   /UTW              D(B)       0VL


    The connector main frame should be connected to PE
    The crossed pins are reserved.




    14
                                                                  Chapter 4
                                                                                   A
                                                    4. Line tool characteristics

4.1 Principles
In order to be conformant to the UNI-TELWAY interface previously defined, the
device should include the following characteristics :
•    Generate the D(A) , D(B) and 0VL signals as required by the EIA RS485
     norm, as defined in section "data transmission" and "connection
     accessories".
•    Isolate the signals from the device as defined in section "isolation".
•    Know how to read the address, parity and control signals, with respect to
     the coding rules defined in section "signals coding rules".
•    Use the proper connector and connect signals on the appropriate pins, as
     defined in section "connector".




4.2 Line emitter/receiver
The D(A), D(B) and 0VL signals should be generated by a line emitter/receiver
conformant to EIA RS485 norm (see figure below).

They are issued from the classical RX and TX signals coming from/going to the
UART through the isolation layer.

In emission, the RS485 emitter validation signal should be available. It should
be validated only during the station data emission time. Otherwise, conflicts on
the transmission mine may occur.
In all other cases, and even when the device is in INIT phase or un-powered, the
emitter should be invalidated (A and B outputs at high impedance).

In reception, the RS485 receiver can be constantly validated (permanent
"hearing").

               Emission                        Reception
  Enable

                    D(A)
  TX                                                         RX
           E                                        R
                    D(B)

                    0VL



               towards UNI-TELWAY interface



                                                                             15
A

    4.3 Conventions
    The successive symbols from by the data link layer and given to the physical
    layer will be furnished by an UART generating a three symbols code :
    Symbol_PHY[H] = "1" binary element or MARK
    Symbol_PHY[L] = "0" binary element or SPACE
    Symbol_PHY[O] = OPEN emitter condition

    Those symbols will be translated on the transmission line onto RS485
    normalized states.

              Symbol_PHY             Line state               D(A)-D(B)
                  H                 MARK or "1"               < -200 mv
                  L                 SPACE or "0"              > +200 mv
                  O                 MARK or "1"               < -200 mv




    4.4 Line polarization
    The usual RS485 line emitter/receiver found in the shops comprise inverted (I)
    and non inverted (NI) inputs/outputs on the line side. They follow those
    conventions :
    V(NI)-V(I) < -200 mV             èRX or TX = logical "0" (GND)
    V(NI)-V(I) > 200 mV              èRX or TX = logical "1" (Vcc)
    -200 mV < V(NI)-V(I) < 200 mV    è non guarantied state ("1" or "0").

    When no emitter is valid (Symbol_PHY[O]), D(B) - D(B) tends to stabilize around
    0V (line loaded by the connected stations). In this case, the logical state of the
    transmission line is not guarantied (refer to RS485 conventions)

    In order to be conformant to UNI-TELWAY conventions defined in previous
    section "conventions", it is necessary to force the transmission line onto MARK
    ("1") state when no emitter is valid (Symbol_PHY[O]).

    This will be realized by pre-polarizing the transmission line at the device level, by
    forcing a potential difference between D(A) and D(B) such that :

    D(A) - D(B) < -200 mV at idle state.

    Each device connected should comprise two polarization resistors on lines D(A)
    and D(B) as part of the general line polarization conformant to the figure below :


    16
                                                 Line tool characteristics   4    A



                      +VL (5V)


                   4,7 Kohms (1/4 W)

               D(B)
                                                             RX
               D(A)
                                               RS485
                   4,7 Kohms (1/4 W)          receiver


                         0VL

Note :
The connecting sense of the emitter/receiver inputs/outputs RS485 regarding
the D(A) and D(B) signals of the transmission line will depend on the
implementation. The isolation stages situated between the line inputs/outputs
and the UART being a possible cause of inversion of the RX and TX signals, the
single criteria retained will be the conformity to the UNI-TELWAY conventions
detailed in section "conventions".




                                                                             17
A




    18
                                                                 Chapter 5
                                                                                   A
                                       5. Connection method and accessories

5.1 Generalities
Before all, UNI-TELWAY is mainly a multi-point bus on which stations of various
type are interconnected (Programmable Logic Controllers, CNCs, speed
controllers…)

In order to homogenize the connecting operations of those various devices,
Schneider Automation offers in its product catalogue some accessories
designed to facilitate the connecting implementation.




5.2 Two-channels subscriber socket
Reference: TSX SCA 62

This is a tap link situated close to the device and seen by the latter as a UNI-
TELWAY connector comprising all signals defined in chapter 3 (Sub D 15 pts
female).

Inside, is included an address coding unit with switches, as described in
section "particular conventions".

It comprises also a impedance end of line adaptation which should be used
when the subscriber socket is at one extremity of the line.

On the transmission line side, the subscriber socket is connected by one (line
extremity) or two (middle) screw connectors, as described in section "Particular
conventions".

A standard device will be connected to the subscriber socket using a connection
cable (see next section).

In order to diminish the connection cost, the subscriber socket comprises two
channels (1 and 2) allowing the connection of two UNI-TELWAY devices. Each
channel has its own independent address coding unit.

Refer to Schneider Automation catalog and technical documentation for further
details.
Note
Inside the subscriber socket, the /UTW signal is connected to COMMON (strap
between connector pins 5 and 12) because usable only for UNI-TELWAY
functioning with UNI-TELWAY protocol (/UTW=0).

                                                                             19
A

    5.3 Passive T-junction box
    Reference: TSX SCA 50.

    This is a passive box comprising a printed circuit with three screw units allowing
    the T connection of a derivation on the main frame of the UNI-TELWAY
    transmission line.
    This box ensures the electrical signals continuity in the three directions,
    including also the shielded continuity.




    5.4 Bus connecting cable
    This is a special cable with, at each end, a 15 pins male SUBD connector
    conformant to the standard defined previously.
    It is designed to wire a standard device on the subscriber socket.

    The device, which should be able to manage the physical address through the
    standard interface, will read this address in the subscriber socket to which it is
    connected.


    Note :
    •    The address signals being not isolated, the cable length should be limited
         to 1,5 meter.
    •    It is possible with a compatible but not standard device to link it to the
         subscriber socket using a specific cable. It is then the furnisher
         responsibility to make and provide it.




    5.5 Standard junction box
    It is the best suited connecting mode for the standard device (using the
    standardized SUBD 15 pins connector).
    The junction box allows the direct linking without using the couple subscriber
    socket + cable.
    It is made of plastic, and comprises a male 15 pins SUBD connector on the
    device side and one or two screw terminal blocks conformant to section
    "particular conventions". The one blocks version is used to connect the device at
    one end of the bus segment. It comprises the bus line terminator. The two



    20
                                      Connection method and accessories        5    A
blocks is designed to connect the device anywhere else on the bus, allowing the
cable chaining.
In both cases, the addressing function is provided with a switches block.

Note
The /UTW signal is internally connected to COMMON (strap between pins 5 and
12 of the connector) because only usable with UNI-TELWAY devices functioning
with UNI-TELWAY protocol (/UTW=0)




5.6 Line topology
The device can be connected to the UNI-TELWAY transmission line in two ways :

5.6.1 Derivation connection

     Main segment                 Derivation                  Main segment
                                     tap


                                         Derivation segment
                                         (max 20 m)



                                  Subscriber
                                    socket


                                         junction cable
                                         (max 1.5 m)


                                 UNI-TELWAY
                                   device



In this case, the derivation segment should be made of the same cable as the
main segment and should not exceed 20 meters. The signal continuity,
including the shielding is insured directly by the derivation tap. The subscriber
socket or junction box is connected at the end of the derivation segment.




                                                                              21
A

    5.6.2 Chaining connection




         Main segment               Subscriber               Main segment
                                      socket


                                           junction cable
                                           (max 1.5 m)


                                    UNI-TELWAY
                                      device



    In this case, the subscriber socket or junction box is directly connected to the
    main segment of the transmission line.

    5.6.3 Mixed connections
    Mixing up the two connection modes is possible on the UNI-TELWAY
    transmission line.




    22
UNI-TELWAY reference manual                               Contents
Link&Network protocol specification                       Section B




Chapter                                                       Page
1. Introduction                                                   3
                                                                      B
       1.1   Presentation                                         3
       1.2   Objectives                                           3
2. Services description                                           5
       2.1  Simple service                                        5
            2.1.1 Master side                                     5
            2.1.2 Slave side                                      6
       2.2 Standard service                                       7
            2.2.1 Addressing principle                            7
            2.2.2 Master side                                     7
            2.2.3 Slave side                                      9
3. Link layer protocol                                           11
       3.1  Principles                                           11
       3.2  Character format                                     11
       3.3  speed                                                12
       3.4  Addressing                                           12
       3.5  Character transparency with <DLE> insertion          12
       3.6  Exchange management                                  13
       3.7  Character timings                                    14
            3.7.1 Inter-Character Time                           14
            3.7.2 Minimum Turn-around time                       14
            3.7.3 Line validation signals                        15
            3.7.4 Summary                                        16
       3.8 Algorithms                                            17
       3.9 Flow control                                          27
       3.10 Error detection                                      27
            3.10.1 Characters errors                             27
            3.10.2 Frame errors                                  27
            3.10.3 Protocol errors                               28
       3.11 Error processing                                     28
       3.12 LPDU format                                          29
4. Network protocol                                              31
       4.1   Principles                                          31
       4.2   NPDU format                                         31
5. Network management                                            33
       5.1   Configuration parameters (recall)                   33
       5.2   Slaves startup and monitoring                       33
       5.3   Bus monitoring by slaves                            34
       5.4   Defaults log                                        34
6. Examples                                                      35
       6.1   UNITE mirror request from slave to slave            35
       6.2   Diffusion from master                               36


                                                                  1
    UNI-TELWAY reference manual           Contents
    Link&Network protocol specification   Section B




B          6.3   DLE duplication                 36
    7. Glossary39




    2
1
                                                            Chapter 1
                                                            1. Introduction

1.1 Presentation


UNI-TELWAY is a generic name used to define a set of protocols published by
SCHNEIDER Automation in order to interconnect SCHNEIDER Automation            B
devices and third party devices with each other.
This document describes the link and network layers allowing connecting any
type of device, from supervision to sensors, to the processing unit.
The link layer allows to exchange data between a master and one or more
slaves.
The network allows two types of services:
•   Data exchange between master and slaves.
•   Slave access to the XWAY inter-network services.


Note
The application layer is the UNITE messaging protocol. For most useful
services, the list and explanations can be found in document TSX DR NET E.




1.2 Objectives
The aim is to allow two types of applications:
•   Connecting sensors to the processing unit.
•   Connecting supervision monitors to the SCHNEIDER Automation network
    architecture.

Those services being offered for third party products, the protocol
implementation remains reasonably simple so that it can be implemented
without trouble.




                                                                         3
B




    4
                                                                    Chapter 2
                                                            2. Services description


The services offered by the link and network layers are of two types:
•   Data exchange between master and slaves
•   Access to the XWAY inter-network service through the master                       B
Those two services can be used simultaneously.

From now on, they will be called simple service for the first one and standard
service for the second one.




2.1 Simple service
It allows to exchange either acknowledged data between the master and any
single slave, or emit non-acknowledged data from the master towards all slaves
(diffusion).

The data transmission is acknowledged for point to point exchange and non-
acknowledged for diffusion.

It does not allow communication between two slaves.

The maximum length of data exchanged is 128 bytes.


2.1.1 Master side
Data emission with acknowledge:

SI_DATA_ACK.request(peer_address, data) : emission request
SI_DATA_ACK.confirmation(peer_address, result) : result of emission

peer_address identifies the targeted slave. Possible values are [1..253]

The possible result values are:
•   Data transmitted & acknowledged
•   Data transmitted & refused
•   Data transmitted & not acknowledged
•   Data not transmitted & destination station in trouble




                                                                                 5
    Data diffusion without acknowledge:

    SI_DATA.request(peer_address, data) : diffusion request
B   SI_DATA.confirmation(peer_address, result) : result of emission

    peer_address indicates diffusion and is set to 255.

    The possible result values are:
    •   Data transmitted
    •   Data not transmitted

    Data reception (from slave):

    SI_DATA.indication(peer_address, data) : reception indication

    peer_address identifies the requester slave. Possible values are [1..253]


    2.1.2 Slave side
    Data emission:

    SI_DATA_ACK.request(data) : emission request
    SI_DATA_ACK.confirmation(result) : result of emission

    The possible result values are:
    •   Data transmitted & acknowledged
    •   Data transmitted & refused
    •   Data transmitted & not acknowledged
    •   Data not transmitted (abandon)

    Emission cancel:

    SI_DATA_ACK.cancel() : abandon of the last emission request

    Data reception:

    SI_DATA_ACK.indication(data) : reception indication




    6
                                                       Services description 2


2.2 Standard service
This service allows to differentiate several entities on the master side and more
particularly, in conjunction with the XWAY communication service provided by the
master, to exchange data throughout the whole SCHNEIDER Automation multi-            B
network architecture.

This service allows to exchange non-acknowledged data towards all slaves
(diffusion)

The maximum length of exchanged data is 128 bytes.

The Acknowledge is made at the link layer level (except in the case of diffusion),
the end-to-end transfer should be realized by the application.

The local_address parameter is added on the master side (peer_address on
slave side) in order to support the XWAY addressing service. The corresponding
parameters are underlined in the following functions.


2.2.1 Addressing principle
It follows the XWAY addressing principle. Refer to documentation TSX DR NET
E that provides all details in a very comprehensive manner.

The device supporting UNI-TELWAY is able to send a message to any station
connected to the XWAY network architecture (on the same network or on
another network interconnected by a bridge).

The master makes the conversion between the slave address and its XWAY
address.

This service does not provide any end-to-end transport control, which should be
supported by the application.


Note
In XWAY architecture, the master and the slaves are part of the same "station",
which refers to an high level processing unit. Slaves are accessed using a 5
levels XWAY addressing mechanism.


2.2.2 Master side
Data emission with acknowledge:


                                                                                7
    ST_DATA.request(peer_address, local_address, data) : emission request
    ST_DATA.confirmation(peer_address, result) : result of emission

    peer_address identifies the targeted slave. Possible values are [1..253]
B
    local_address identifies the emitting entity, which is any entity of the XWAY
    network.

    The possible result values are:
    •   Data transmitted & acknowledged
    •   Data transmitted & refused
    •   Data transmitted & not acknowledged
    •   Data not transmitted & destination station in trouble

    Data diffusion without acknowledge:

    ST_DATA.request(peer_address, local_address, data) : diffusion request
    ST_DATA.confirmation(peer_address, result) : emission result

    peer_address indicates diffusion and is set to 255.

    local_address identifies the emitting entity, which is any entity of the XWAY
    network.

    The possible result values are:
    •   Data transmitted
    •   Data not transmitted

    Data reception (from slave):

    ST_DATA.indication(peer_address, local_address, data) : reception indication

    peer_address identifies the emitter slave. Possible values are [1..253]

    local_address identifies the emitting entity, which is any entity of the XWAY
    network.




    8
                                                      Services description 2


2.2.3 Slave side
Data emission:

SI_DATA_ACK.request(peer_address, data) : emission request                     B
SI_DATA_ACK.confirmation(result) : emission result

peer_address identifies the emitting entity, which is any entity of the XWAY
network.

The possible result values are:
•   Data transmitted & acknowledged at link layer level
•   Data transmitted & refused at link layer level
•   Data transmitted & not acknowledged
•   Data not transmitted (abandon)

Emission cancel:

SI_DATA_ACK.cancel() : abandon of the last emission request

Data reception:

SI_DATA_ACK.indication(peer_address, data) : reception indication

peer_address identifies the emitting entity, which is any entity of the XWAY
network.




                                                                           9
B




    10
                                                                     Chapter 3
                                                              3. Link layer protocol

3.1 Principles
The link layer is asymmetrical, with a fixed master and one or more slaves.

The maximum number of slaves is set to 253.                                             B
The master polls each slave one by one and will transmit data if necessary. The
link layer does only permit master çè slave exchanges.

A message is a list of characters, starting by identifier <DLE><STX>. The data
integrity is guarantied by both the parity bit for each character and the message
checksum.

The character transparency is guarantied by the <DLE> insertion.

The exchange validity is controlled at the character level, the message level and
the protocol consistency.

The flow control is managed with each frame, by using a negative acknowledge
(NACK).


3.2 Character format


1 bit          START
8 bits         DATA
1 bit          PARITY
1 bit          STOP

The parity is odd (the data bits string + parity contains an odd number of "1").

PARITY = NOT(bit0+ bit1+ bit2+ bit3+ bit4+ bit5+ bit6+ bit7)

"+" being addition modulo 2.

Start     0     1      2       3     4      5      6      7     Parity   stop

                                         data
note
It is possible to customize the START and STOP bits number, the presence and
value of PARITY in some specific applications. Those services are optional and
more or less provided depending on the product.



                                                                                   11
    3.3 speed
    The transmission speed is 9600 bauds by default.
B   The user can configure this value. The way it is accessed depends on the
    products.


    3.4 Addressing
    The bus being multi-point, it is necessary to configure the number of slaves in
    order to optimize the polling cycle, and the address of each of them.

    The protocol does not take into account the consistency control of the address
    parameters (unicity, range limits).

    We can have up to N slaves numbered consecutively from 1 to N. N is limited to
    253 by the link layer.

    Address 255 is dedicated to diffusion

    Addresses 0 and 254 are reserved.


    3.5 Character transparency with <DLE> insertion

    The <ENQ> and <STX> command characters are preceded by <DLE>

    The <DLE> character in field <data> is duplicated.

    If field <length> is equal to <DLE>, it is duplicated.

    Field <addr> is never duplicated.

    Field <BCC> is never duplicated.

    The BCC calculation is made after padding with <DLE>, and includes
    consequently the added <DLE> characters.

    The <length> field is filled in before padding. It does not include the added
    <DLE> characters.




    12
                                                                   Link layer protocol 3


3.6 Exchange management
The master initiates all exchanges, which are either messages from master to
slave (selecting), or emission invitations for data transmission from slave to
master (polling).                                                                                 B
The master alternates the emission invitation cycles (polling) and emission cycles
(selecting). The polling order is based on ascending slaves numbers. The
emission order towards the slaves is based on the incoming messages order
from upper layer.

                   Master                                              Slave

selecting
       <DLE><STX><addr><length><data><BCC>        è
                                                  ç   <ACK> or
                                                      <NACK> or
                                                      silence or
                                                      undefined


Polling
                           <DLE><ENQ><addr>       è
                                                  ç   <EOT> or
                                                      silence or
                                                      undefined or
                                                      <DLE><STX><addr><length><data><BCC>
                                     <ACK> or     è
                                    <NACK> or
                                     silence or
                                     undefined


Master processing:

While (;;) {
       For (ADR =ADR_MIN; ADR<ADR_MAX; ADR++) {
             POLLING(ADR);
             If (message to transmit)
                      SELECTING(peer);
       }
}
The master should questions each slave periodically, even it if does not expect
any answer (the slave should be able to ask a question). All slaves have identical
speaking rights. It is essential that the master polls after a message emission in
order to provide this speaking right and thus avoid some undesired
communication blocking phenomenon.
Note: In the case of reception of an invalid frame, the master decides the end of emission when
the inter-character time expires (see section "error detection").



                                                                                            13
    3.7 Character timings
    DE          Data Enable. Request from microprocessor to validate the emission
                state.
B   OE          Output Enable. Line driver validation (effective emission state).
    Toe         Time between DE validation and OE validation ≈150µs (opto-
                coupler)
    Tod         Time between DE de-validation and OE de-validation ≈50µs (opto-
                coupler).
    TPL         Time between emission request and first character emission.
    TLL         Time between last character emission and line release.
    TRet        Turn-around time.
    ICT         maximum Inter-Character Time.
    Tbit        Bit emission duration on the line (ex: 19200 bauds à 52µs).

    note : the accurate emission end can be evaluated as ½ bit after register bit
    TSRE (Shift Register Empty) falls down (middle of STOP bit).

    3.7.1 Inter-Character Time
    This value is customizable within a large range of values, from the default of 5
    characters transmission time (around 50 Tbit) up to 1 or 2 seconds for a modem
    transmission.
    It should be noted that ICT counts for the global transmission performance, as
    the master should wait until ICT expires each time it polls a slave.

    A typical value is 30 ms (valid only for speed ≥ 2400 bauds).

    3.7.2 Minimum Turn-around time
    All devices (master or slaves) should respect a minimum delay before next
    message emission or response (TRet), in order to allow the peer device returning
    to idle state (emitter de-validation).
    This delay is fixed to the transmission time of around a single character, that is,
    11 bits.

                                     TRet > 10 Tbit.




    14
                                                         Link layer protocol 3


 3.7.3 Line validation signals


 Line validation start-up
                                                                                  B
 The delay between emission request (DE) and line driver validation (OE)
 corresponds to the time between processor command and effective validation by
 the opto-coupler.

                                  Device A
                                             Tod
DE
              Toe
OE

   TPL                                       TLL
Data                Emission


                                             TRet

                                  Device B
DE

                                              TPL                           TLL
Data                Reception                            Emission


 The time between emission request and start of data emission should be longer
 than Toe in order not to truncate the transmitted data.


                            Toe



                                             Emission


                       TPL
                                       Truncated data

 It results in:

                                    TPL > Toe ≈ 150 µs




                                                                            15
    Simultaneous line validation

    If device B TRet is too short regarding device A TLL and device B TPL (TRet <
B   TLL + TPL), , the device B DE validation may be raised while device A DE signal
    is still up, producing a simultaneous DEs validation.

                         DE
           device A
                                            TLL
                             emission


                         DE
           device B                                  TPL
                              reception         TRet          emission


                                           simultaneous DEs


    Considering the Toe and Tod times for DE delays on the line, TPL should be
    limited so that TRet-TLL-Tod-TPL+Toe > 0

                                   TPL < TRet - TLL - 50µs


    3.7.4 Summary


                       Min                     Max
     TPL              150µs               TRet-TLL-200µs           ≤ 38400 bauds
                                                                (otherwise TPLmin >
                                                                      TPLmax)
    TLL                  0                    2 Tbit
    TRet              10 Tbit                  ICT
     ICT              50 Tbit              1-2 seconds          typical value : 30ms
                                            (modem)                (≥2400 bauds)




    16
                                                   Link layer protocol   3
3.8 Algorithms
Presented below are the graphs for
1. master side :
    •   main graph
    •   emission (end to end, diffusion)                                      B
    •   reception (invitation to slave emission)
2. slave side :
    •   main graph
    •   emission
    •   reception (end to end, diffusion)




                                                                         17
                                Master side - main graph

B




                                    Next slave


         End to end                                                No message
          message                       Diffusion                  to emit
                                        message
                 End to end            to diffuse
                  Emission                       Diffusion
                first attempt                    emission

           silenc
                 e                     Other            End of
                End to end             case             emission
                 Emission
               2nd attempt

            End of
          emission


                                      Emission
                                    invitation and
                                      reception

                                               End of reception




    18
                                                           Link layer protocol   3

              Master side - end to end emission - First attempt



                                                                                      B


            Emission
         <DLE><STX>……

                     End of emission

             Wait for
           Acknowledge

                                            <ACK> or                    Other
                     silence                <NACK>                      sequence
                                                                        (A1)
                                  Wait for slave
                                  turn-around
                                      time
                                                   No silence (A2)


                           End of wait
                                 (A3)                            Wait for
                                                                 silence



                                                       End of wait




Action A1: result "data transmitted, non acknowledged"
Action A2: result "data transmitted, non acknowledged"
Action A3: result "data transmitted, acknowledged if <ACK>", refused if <NACK>




                                                                                 19
                 Master side - end to end emission - second attempt



B

           Emission
         <DLE><STX>……

                   End of emission

            Wait for
          Acknowledge

                                            <ACK> or                    Other
                   Silence (A1)             <NACK>                      sequence
                                                                        (A2)

                                  Wait for slave
                                  turn-around
                                      time
                                                   No silence (A3)


                         End of wait
                               (A4)                              Wait for
                                                                 silence



                                                   End of wait




    Action A1: result "data transmitted, non acknowledged"
    Action A2: result "data transmitted, non acknowledged"
    Action A3: result "data transmitted, non acknowledged"
    Action A4: result "data transmitted, acknowledged if <ACK>", refused if <NACK>




    20
                                   Link layer protocol   3

Master side - diffusion emission



                                                              B


      Emission
    <DLE><STX>……
               End of emission.
               Result = data transmitted




                                                         21
                         Master side - invitation to slave emission



B

                                  Emission
                            <DLE><ENQ><slave addr>

                                                End of emission (polling)

                                     Wait for
                                    response

                                                                                    EOT/
     Silence                                <DLE><STX><slave addr>…                 undefined

                                    Message
                                    reception

                                                                  Invalid
                 T1                        T2                     message

           Wait for           Wait for                 Wait for               Wait for
            Slave              Slave                    Slave                  Slave
         turn-around        turn-around              turn-around            turn-around
             time               time                     time                   time
                  End of wait          End of wait              End of wait          End of wait

          <ACK>                  <NACK>
         response               response
                 End of                    End of
                 Response                  Response
                 (A1)




    T1: valid message / message can be accepted
    T2: valid message / message can not be accepted
    A1: indication of reception


    22
                                                                   Link layer protocol   3

                                     Slave side - main graph



                                                                                               B




                           wait for message
                          or invitation to emit




        polling and            polling and           selecting slave       selecting
        msg to emit            no msg to emit        address               diffusion address

  Wait for              Wait for               Wait for             Wait for
   Slave                 Slave                  Slave                Slave
turn-around           turn-around            turn-around          turn-around
    time                  time                   time                 time


        End of wait            End of wait           End of                End of
                                                     reception             reception

 emission             response
                       <EOT>

        End of                 End of
        emission               Response




                                                                                         23
                 Slave side - Emission

B


           Emission
         <DLE><STX>….

                  End of emission.

            Wait for
          acknowledge


                 <ACK> : data acknowledged
                 <NACK> : data refused
                 other character : data not acknowledged
                 cancel (by slave) : data not acknowledged




    24
                                                               Link layer protocol   3

                      Slave side - End to end reception



                                                                                          B


                                    End to end
                                    message
                                    reception



                                                                       No valid
                      T1                         T2                    message


                Wait for               Wait for
                master                 master
              turn-around            turn-around
                  time                   time

                      End of wait                End of wait

               <ACK>                   <NACK>
              response                response
                      End of                     End of
                      response                   response
                      (A1)




Transition T1: valid message / message can be accepted
Transition T2: valid message / message can not be accepted
Action A1: indication "end to end data reception"




                                                                                     25
                         Slave side - diffusion reception



B

                             Diffusion
                             message
                             reception

                                      End of reception (A1)




    Action A1: if valid message AND message can be accepted, then indication
    "reception of data in diffusion"




    26
                                                         Link layer protocol   3
3.9 Flow control
The message receiver can be saturated (out of buffers…). In this case, it waits
until the end of the message, controls BCC and if the received message is valid,
it emits <NACK>. If the message is invalid, no response should be emitted.
                                                                                    B
Note
This rough mechanism (wait until the end of message before getting the
information that the device is not available) is efficient only if flow control
mechanism is rarely activated. The device should make such as its reception
buffers are as much available as possible.




3.10 Error detection


The error detection has various forms:
•   Character errors
•   Frame errors
•   Protocol errors

The general rule is when in doubt, don't! A slave device having detected an
invalid sequence will shut up, and the master will then fall in time-out.

Each device counts the errors, by type. Those counters can be red and initialized
by application services.

3.10.1 Characters errors
The following errors are detected at reception:
•   Incorrect character format
•   Incorrect character parity
•   Overwrite of character in reception ("overrun").

3.10.2 Frame errors
The following errors can be detected:
•   BCC error
•   Incorrect length field
•   Inter-character error: time between two characters exceeds the maximum
    delay value (ref section "character timings"). Only the master makes this
    control.



                                                                               27
    3.10.3 Protocol errors
    •    Sequencing: the control character or sequence of control characters
         received is not consistent with the expected emitter state. For example, a
         slave receiving a synchronization sequence during message reception
B        considers that the interrupted message is lost.
    •    Response time envelope error: on message emission or polling, the
         master does not receive any response (<ACK, <NACK>, <EOT>) within the
         maximum delay authorized.

    The response time envelop equals the Inter-Character Time (ICT). Refer section
    "character timings".




    3.11 Error processing


    Emitter processing (master)

    If no response from the slave (silence), the master should re-emit immediately
    the message. If the second attempt fails, the message is lost.

    When in doubt (invalid character reception, or different from <ACK>, the master
    does not re-emit, in order to avoid message duplication.

    Emitter processing (slave)

    After message emission, the slave should be in listening state. If the first
    character is <ACK>, the message has been correctly received. If no response
    before next polling, the slave will re-emit the same message at next polling. If
    the second attempt fails, the message is lost.

    In all others cases, the slave does not re-emit, in order to avoid message
    duplication.

    Error counters management

    In order to facilitate the line diagnostic, the devices manage error counters for
    various error types. The access mode to the counter values is device-
    dependent.




    28
                                                       Link layer protocol   3
3.12 LPDU format


Master èslave format:

  DLE       STX       addr     length                data                BCC      B
Slave èMaster format:

  DLE       STX       addr     length                data                BCC



With:

addr     Byte. Slave station address
         Value comprised in range [1..255]
length   Byte. <data> field bytes number, before padding with <DLE>s
         Value comprised in range [1..134]*
BCC      Byte. Sum modulo 256 of the LPDU bytes (except BCC) from header
         <DLE> to the last byte of <data> calculated after padding with <DLE>s.
         Value comprised in range [1..255]


* the maximum length value of 134 corresponds to maximum NPDU size :
standard service format with 128 bytes of data (see next section).




                                                                             29
B




    30
                                                                   Chapter 4
                                                              4. Network protocol

4.1 Principles


The protocol allows differentiating the service used, and in the case of standard
addressing service, the entity with which the slave talks, through the master.
                                                                                    B



4.2 NPDU format


Each individual grayed rectangle corresponds to 1 byte

Simple service format:


  code                                data : 128 bytes max



Standard service format:

  code        Net     Sta      Gate      Ext1     Ext2       data : 128 bytes max


                            XWAY_ADDR
Code:

Hexadecimal      Decimal
00H              0               Simplified UNI-TELWAY datagram
20H              32              Standard UNI-TELWAY datagram
22H              34              Refused UNI-TELWAY message
                                 Set when
                                 •   Routing error (wrong XWAY address, the
                                     slave acts as a gateway and the distant is
                                     unreachable)
                                 •   Lack of resources at application level (at
                                     network level, a NACK is returned).

The other values are reserved for further use.

A device receiving a message with unknown code is considered as erroneous
and not taken into account (silence).

XWAY_ADDR:

                                                                               31
    The XWAY_ADDR area corresponds to
    •   The XWAY source address when the message is sent by the master (the
        destination is the Uni-telway slave address).
B   •   The XWAY destination address when the message is sent by the slave (the
        source is the Uni-telway slave address).

    It allows 3, 5 and 6 levels addressing exchanges.

    Net      Network value.
    Sta      Station value.
    Gate     Gate value.
    Ext1     Meaningful only with particular values of Gate (ref to TSX DR NET E
             documentation). Otherwise, set to 0.

              if Gate=5 : value = module
              bits 7-4 è rack
              bits 3-0 è slot
              or FEh for my module

             if Gate=8 : value = selector/reference
             bits 7-4 è selector
             bits 3-0 è reference
    Ext2     Meaningful only with particular values of GATE (ref to TSX DR NET E
             documentation). Otherwise, set to 0.

              if Gate=5 : value = channel

              if Gate=8 : value = connection point


    Some restrictions should however be noted:

     6 levels addressing (gate 8) is handled only by Premium and Micro PLCs.
     Consequently, exchanges with devices connected to FIPIO are not possible
     with serie 7 PLCs (except by using the Schneider Automation UNI-TELWAY
     PC driver in a particular mode).




    32
                                                                   Chapter 5
                                                       5. Network management


This chapter is not exactly part of the protocol definition. The UNI-TELWAY bus
consistency requires that the device would have a rather common family
likeness regarding the diagnostics and startup operations.
                                                                                      B


5.1 Configuration parameters (recall)
•   Number of slave stations (master only) (default=1).
•   Transmission speed (default=9600 bauds).
•   Character format (default=1 start bit - 8 data bits - odd parity - 1 stop bit).
•   Max Inter-Character Time & max slave response delay. (Default = 5
    characters).




5.2 Slaves startup and monitoring


The master controls all slaves specified in the network configuration. Any slave
detected as not operational should be excluded of the controlled slaves pool
(when possible), in order to avoid waste of bus cycle time.

The advised algorithm is:
•   A slave is seen as not operational after two consecutive transmission faults
    detected by the master.
•   A faulty slave is polled periodically (each 10 network cycles for example) by
    the master and set of operational again if capable of answering.

The following faults are seen as transmission faults:
•   On SELECTING: two attempts followed by silences.
•   On POLLING: two consecutive polling followed by silences or unknown
    responses.




                                                                                33
    5.3 Bus monitoring by slaves


    The slaves' devices can check whether they are polled periodically by the
    master. When the polling does not occur during an abnormal duration (for
B   example 7 seconds), switching on a "NET" LED on the front panel can indicate it.


    Note
    Any detected protocol error produces de-synchronization between the
    communicating entities and a proper restart is thus necessary with re-
    initialization of the communication context.




    5.4 Defaults log
    An defaults history record is managed by each device with counters that can be
    read and reset by using UNITE message requests (READ_COUNTER and
    CLEAR_COUNTER).

    Emission control
    Ctr 0: number of non-acknowledged emitted messages (silence or undefined)
    Ctr 1: Number of refused emitted messages (<NACK>)

    Reception control
    Ctr 2: Number of non-acknowledged received messages (silence)
    Ctr 3: Number of refused received messages (<NACK>)

    Those counters are 16 bits signed integers.




    34
                                                                        Chapter 6

                                                                          6. Examples

6.1 UNITE mirror request from slave to slave
The message is transmitted in two steps:                                                     B
slave 4 ↔ master and master ↔ slave 6.                  ‚                      •

Standard datagram (code=20).
Selecting with diffusion (FF) of V1 mirror
request (FA xxxx) on all slaves.                                 ƒ    „
Slave 1 connected
                                                                             slave 4
When master polls address 1, the slave                 slave 6
answers, and master acknowledges.




          slave 4                        master                           slave 6
                               ç <DLE><ENQ><addr>
                                 10 05 04
 <DLE><STX><addr><length>      è
 <code><XWAY addr><mirror
 request><BCC>
 <10 02 04 04 20 00 FE 05 FE
 6A FA 00 05 14>
                               ç <ack>
                                 <DLE><STX><addr>           è
                                 <length><code>
                                 <XWAY addr>
                                 <mirror request><BCC>
                                 <10 02 06 09 20 00 FE 05
                                 FE 04 FA 00 05 14>
                                                            ç <ack>
                                  <DLE><ENQ><Addr>          è
                                  <10 05 06>
                                                            ç <DLE><STX><Addr><length><c
                                                              ode><XWAY       addr><mirror
                                                              answer><BCC>
                                                              <10 02 06 08 20 00 FE 05 FE
                                                              04 FB 05 xx>
                                 <ack>                      è
                               ç <DLE><STX><addr><length
                                 ><code><XWAY
                                 addr><mirror
                                 answer><BCC>
                                 <10 02 04 08 20 00 FE 05
                                 FE 06 FB 05 xx>
 <ack>                         è




                                                                                       35
    6.2 Diffusion from master


    Simple datagram (code=0).
    Selecting with diffusion (FF) of V1 mirror request (FA xxxx) on all slaves.
B   Slave 1 connected
    When master polls address 1, the slave answers, and master acknowledges.

                       master                                   slave
    <DLE><STX><addr><length><code><mirror    è
    request><BCC>
    <10 02 FF 04 00 FA 00 05 14>
                                             ç [silence]
    <DLE><ENQ><Addr>                         è
    <10 05 01>
                                             ç <DLE><STX><Addr><length><code><mirror
                                               answer><BCC>
                                               <10 02 01 03 00 FB 05 16>

    <ack>                                    è




    6.3 DLE duplication
    Request with <DLE> value in data field. <DLE> should be duplicated
    V1 Mirror request (FA xxxx) on slave address 5

                       master                                   slave
    <DLE><STX><Addr><length><code><mirror    è
    request><BCC>
    <10 02 01 05 00 FA 01 10 10 04 37>
                                             ç <ack>
    <DLE><ENQ><Addr>                         è
    <10 05 05>
                                             ç <DLE><STX><Addr><length><code><mirror
                                               answer><BCC>
                                               <10 02 01 04 00 FB 10 10 04 36>

    <ack>                                    è




    36
                                                                      Examples         6

Request with <BCC> = 10H (=<DLE>). <DLE> should not be duplicated.
V1 mirror request (FA xxxx) on slave address 0FH (=<DLE>, should not be
duplicated as well).

               master                                        slave                         B
<DLE><STX><Adr><length><code><mirror   è
request><BCC>
<10 02 0F 04 00 FA 01 F0 0F>
                                       ç <ack>
<DLE><ENQ><Adr>                        è
<10 05 0F>
                                       ç <DLE><STX><Adr><length><mirror answer><BCC>
                                         <10 02 0F 03 00 FB F0 0E>
<ack>                                  è




                                                                                   37
B




    38
                                                                                 Chapter 7
                                                                                    7. Glossary


STX            02H
ETX            03H
EOT            04H
ENQ            05H                                                                                     B
ACK            06H
BEL            07H
BS             08H
HT             09H
LF             0AH
VT             0BH
FF             0CH
CR             0DH
SO             0EH
SI             0FH
DLE            10H
NACK           15H


<BCC> ...................................................Byte Check Character. Message checksum.
LPDU......................................................Link Protocol Data Unit
NPDU .....................................................Network Protocol Data Unit
Polling ....................................................emission invitation cycles on all slaves
                                                            connected to the master
Selecting................................................Emission of messages from master to
                                                            slave




                                                                                                 39
B




    40

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:6
posted:2/1/2012
language:English
pages:64
jianghongl jianghongl http://
About