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Glossary of DeviceNet Terms1_1.d

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					Woodhead
50 Northland Road, Waterloo, Ontario, Canada N2V 1N3 P: (519) 725-5136   F: (519) 725-1515 www.woodhead.com




              Glossary of DeviceNet Terms (v1.1)
General
ODVA: Open DeviceNet Vendors Association
Vendor ID: Each vendor (company) developing DeviceNet devices must obtain a vendor ID
from ODVA.
Device Type: There are different classifications for devices (drives, photo-eyes, etc.). These
predefined classifications, are set by ODVA.
Product Code: This is number used by the vendor to identify their different devices.

DeviceNet Wire
It consists of 5 wires, V+ and V- are a shielded twisted pair and CAN_H and CAN_L are also a
shielded twisted pair.
     V- (negative): Black
     CAN_L (low): Blue
     Shield:          Casing, bare wire
     CAN_H (high): White
     V+ (positive): Red

Cabling
   Trunk(Thick): This DeviceNet cable is typically used for the “Trunk”, but can be used for
                 “Drops” also. This is rated for 8Amps.
   Drop(Thin):   This DeviceNet cable is typically used for “Drops”, but can be used for
                 “Trunk” line also. This is rated for 3Amps.
   Medium cable: This is used when you need better current capability than is available with
                 “Thin” cable, but need better flexibility than the “Thick” cable offers.
   Flat media:   This is DeviceNet wiring that is very flexible and allows for quick connecting
                 or disconnecting of devices. This cable has no shield wire.
Tap: This is a passive device used to give multiple connection points on a drop cable, usually
4, 6, or 8 connection points.
Tee: Used to create a connection point for either a drop cable or a device off of the trunk.
   Terminator:      A resistor that is connected between the signal wires to reduce destructive
                    reflections and in DeviceNet to ensure the signal quickly returns to a
                    recessive state.
   Aux or Auxiliary Power: This is typically used to power outputs and sometimes inputs.
                    When the I/O is analog there will always be auxiliary power.

Connector Styles
Sealed:
   Mini:         Largest of the sealed connectors used for DeviceNet and is usually used for
                 trunk wiring and drops.
   Micro:        Smallest sized sealed connector used for DeviceNet and is usually used
                 when connecting devices to the bus.




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50 Northland Road, Waterloo, Ontario, Canada N2V 1N3 P: (519) 725-5136   F: (519) 725-1515 www.woodhead.com


Open-Style:
  Screw\Open Terminal: This connector is not water or even dust proof. It provides an
               easy way of connecting to the bus and also provides a point where a Digital
               Voltmeter can be used for testing.

Communications
  MacID:       Each device on the network must have a unique address and it must be
               between 0 and 63. This is also referred to as the “node” number.
  Baud Rate:   The frequency or speed at which the nodes are sending data on the
               network. DeviceNet supports 125 Kbaud, 250 Kbaud, 500 Kbaud.
  Bus Fault:   This typically occurs when a node, that isn’t powered from just network
               power, has tried to connect to the network and there is no bus power. This
               can also occur if the Baud Rate isn’t the same as the rest of the node(s) on
               the network (usually if you have tried connecting at a baud rate lower than
               what the network is currently at).
  Bus Errors: When a station detects a bad message then a counter is incremented. If a
               station detects an error while it is transmitting, the error count will be
               incremented by a larger value than if it detects an error while not
               transmitting. A good message transmitted or received decrements the error
               counter.
  Bus Warn:    If the station’s error counter (receive or transmit) exceeds 127, a Bus
               Warning occurs and it stops transmitting error frames (Error Passive)Bus
               Off:        When a device is in this state, its error counter (receive or
               transmit) has reached 256 and so it logically removes itself from the network
               and can only be brought out of that state by cycling power to it. If the reason
               for the fault isn’t resolved then it is very likely that it will happen again.
    Master\Client: Responsible for control of all or part of the devices on the network. There
                   can be multiple masters on one network. However, more than one master
                   cannot connect to one device.
    Slave\Server: Device, sensor, controlled by client or master.
    Produced & Consumed Size: This refers to the amount of data that a device has to
                   exchange, on a given I/O connection type (i.e. Poll, Strobe, etc.). This is
                   from the devices perspective so if it indicates it is producing 5 bytes and
                   consuming 10 bytes then it will send 5 bytes out onto the DeviceNet network
                   and consume or take 10 bytes off of the DeviceNet network. From the
                   Scanner\Client\Master point of view this would mean that it would need to be
                   configured for 5 bytes of input and 10 bytes of output, associated with the
                   device discussed above.
    Acknowledgement Fault (Ack Fault): Transmitter sends a message that doesn’t get
                   acknowledged. Note: all receiving nodes, whether they are the intended
                   recipient, must acknowledge receipt of the message. This can also occur if
                   the Baud Rate isn’t the same as the rest of the node(s) on the network
                   (usually if you have tried connecting at a baud rate higher than what the
                   network is currently at).
    UCMM (unconnected message manager):              This is part of the Group 3 message type
                   and is used by the master\client to open a connection to a device that no
                   connection has been established to yet.
    Scan Interval (Inter Scan Delay):         User selectable minimum quiet time to allow other
                   devices access to the network. Scanner\master will not start another scan
                   cycle (even if packet processing is complete).
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Network Configuration
   EDS (Electronic data sheet):     Contains information on the device it has been written for.
                 The information allows the user to be able to configure different attributes
                 within the device to set it up in a way that suits their application. As the
                 complexity of the device increases (proximity sensor versus a drive), so
                 does the complexity of the EDS file.

LEDs
  Network Status: This LED indicates what the status of the device is with respect to the
               network and its interaction with it (i.e. ready to be scanned, being scanned,
               etc.)
  Module Status: This LED indicates the status of the module itself and if there are any
               internal errors that may not allow it to be able to function correctly

Formulas
   Rt= 1/ 1/R1 + 1/R2 + …: This is used to calculate parallel resistance i.e. terminating
                   resistors on a network cable. This will give you an approximation since the
                   resistance will change with cable length, etc.
   V=I*R:          Voltage is equal to current (I) times the resistance (R) where R=L(usually in
                   meters)*Ohms/meter. To find out Ohms/meter for the cable you need to see
                   the manufacturers’ specifications.




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