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Magnetically Actuated Proximity Sensors

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					                    Magnetically Actuated
                     Proximity Sensors




Subject to change                           853
Magnetically Actuated Proximity Sensors
Contents


 Features and Benefits ............................................. 855           Electric Proximity Sensors, Corrosion and
 Switching Characteristics .........................................857                Acid Resistant, Type CRSMEO-4-... .................886
 Functions ..................................................................858   Accessories, Corrosion and Acid Resistant .............887
                                                                                   Electric Proximity Sensors, U-Shape,
 Ordering Information .........................................859                     Type SMEO-4U-... .............................................888
 Overview ...................................................................860   Inductive Proximity Sensors, U-Shape,
 Mounting Bracket Overview .....................................865                    Type SMTO-4U-... .............................................889
 Mounting Bracket Dimensions ..................................866
 Sockets for Sensors with 8 mm Push-In or                                          Cylinders for Tie-rod Cylinders and Cylinders
    M8 x 1 Threaded Plug........................................867                with Integral Sensor Rail
 Sockets for Sensors with M12 x 1 Threaded Plug ....868                            Electric Proximity Sensors
 DUO Cables for Sensors ..........................................869                  With Cable, Type SMEO-1-... ............................891
                                                                                       With Plug, Type SMEO-1-S-... ..........................892
 Sensors for Cylinders with Sensor Groove                                          Inductive Proximity Sensors
 Electric Proximity Sensors, Type SME-8-... .............870                           PNP Output, Type SMTO-1-PS-... ....................893
 Inductive Proximity Sensors, Type SMT-8-... ..........871                             NPN Output, Type SMTO-1-NS-... ....................893
 24 Volt Electric Proximity Sensors,                                               Electric Proximity Sensors
     Type SME-8C-...-24 ..........................................872                  With Cable, Type SME-1-... ..............................894
 230 Volt Electric Proximity Sensors,                                                  With Plug, Type SME-1-S-... .............................895
     Type SME-8C-...-230 ........................................872                   Type SMTO-6-PS-S-LED-24..............................898
 Electric Proximity Sensors,                                                           Type SMTSO-1-PS-S-LED-24 .......................... 899
     Type SMEO-8E-... .............................................874             Heavy Duty Electric Proximity Sensors
 Inductive Proximity Sensors,                                                          Type SMEO-2 ...................................................896
     Type SMTO-8E-... .............................................876                 Type SMEO-2-LED-24... .................................. 896
 24 Volt Electric Proximity Sensors,                                                   Type SME-2-LED-24... ......................................896
     Type SMTS-8E-... .............................................877             Inductive Sensors
 24 Volt Electric Proximity Sensors,                                                   Type SMTO-6-PS-S-LED-24 .............................898
     Type SME-10-...-24 ...........................................878                 Type SMTSO-1-PS-S-LED-24 ..........................899
 Inductive Proximity Sensors, PNP Output,
     Type SMT-10-PS-...-24 .....................................880                Pneumatic Reed Switch
 Inductive Proximity Sensors, NPN Output,                                               Type SMPO-1-H-B .............................................900
     Type SMT-10-NS-...-24 .....................................880
                                                                                   All-Pneumatic Cylinder Switch
 Sensors for Cylinders with Dovetail Sensor                                             Type SMPO-8E ..................................................901
 Groove
 Electric Proximity Sensors                                                        Hall Effect Sensors for Grippers
     Type SME-3-... ..................................................882               Type SMH-S1-... ................................................902
 Inductive Proximity Sensors
     PNP Output, Type SMT-3-PS- ..........................883                      Sensors for Actuators with Threaded Mounting
     NPN Output, Type SMT-3-NS-...........................883                      Holes
                                                                                   Inductive Proximity Sensors, Threaded Body Design
 Sensors for Round Barrel ISO Standard                                                 Type SIEN-M5B-... ............................................908
 Cylinders                                                                             Type SIEN-M8B-... ............................................910
 Electric Proximity Sensors
     Type SMEO-4-... ...............................................884            Sensor Accessories
 Inductive Proximity Sensors                                                            Sensor Tester, Type SM-TEST-1.......................912
     Type SMTO-4-... ...............................................884




854                                                                                                                                     Subject to change
Magnetically Actuated Proximity Sensors
Features and Benefits


  Features:

  s Rapid function monitoring and
    fault detection reduces downtime

  s Easily interfaced to programmable
    controllers

  s Inductive NPN or PNP, electrical
    or pneumatic outputs

  s Molded cable or new plug
    connector design for quick, easy
    installation

  s Compact, lightweight units mount
    directly on cylinder tie-rod or dual
    rail

  s Eliminates cumbersome external
    limit switches

  s AC or DC or pneumatic operation

  Operation:

  Electrical Proximity Sensors
  Type SME-..., SMEO-...                     Magnetically Actuated Proximity Sensors
  The reed switch is molded in a             offer Sensing Versatility
  bakelite case. When the switch enters      Magnetically actuated sensors are primarily designed for use on
  a magnetic field (e.g. a permanent         cylinders manufactured with sensing capability (i.e. permanent magnet
  magnet on a cylinder piston), the          on the circumference of the cylinder piston), but many of them can also
  contacts are closed, and the switch        be used in other areas where the proximity to a magnetic field is to be a
  provides an electrical signal.             criterion for producing electrical control signals.

  Inductive Proximity Sensors
  Type SMT/SMTO
  A magnetic field changes the
  electrical current state of this
  contactless, solid state inductive
  switch. The resulting current change
  is amplified to produce an output
  signal.

  Pneumatic Reed Switch
  Type SMPO-1-H-B
  Similar to an airgate, a reed
  continuously interupts airflow. A
  magnetic field opens the reed. The
  airflow produces a pneumatic output.


  Note: Do not install in areas with high
  magnetic fields (e.g. resistance-welding
  machines).




Subject to change                                                                                                855
Magnetically Actuated Proximity Sensors
Technical Data

When a pneumatic cylinder’s design includes a permanent             Inductive-Magnetic
magnet on the piston, proximity sensors attached to the
outside of the cylinder tube can be used to signal when the
cylinder is at either end stop position and, depending on the
minimum spacing requirements of the sensors used, at one
or more intermediate positions. Three types of sensors are
suitable for use in this application.                                           S
                                                                                                          No Output Signal

Reed Switch
                                                                                              Sensor


                                                                                       a) Sensor not actuated




                                                                                S
                                                                                                          Active Output Signal



                                             S                                                Sensor


                                                                                        b) Sensor actuated




When the piston’s magnet enters the response travel range           The inductive-magnetic proximity sensor is much like a
of the sensor, the magnet’s field causes the contacts of the        normal inductive proximity sensor, using an internal LC
reed switch inside the sensor to close, completing the circuit      oscillating circuit. But rather than using a half-shell core
path to illuminate the LED (if present) and activate the output     design to direct a magnetic field outward, this sensor has a
signal. When the magnet moves out of the response travel            closed-shell core design which does not emit an
range, the reed switch opens again; the LED extinguishes            electromagnetic field. When the piston’s magnet enters the
and the output signal returns to its inactive (i.e. “off”) state.   response travel range of the sensor, the magnet’s field
                                                                    causes saturation of the coil material of the oscillator’s coil.
Built-in protective circuits in a reed switch proximity sensor      This produces a variation in the amount of current drawn by
include current limiting and RC surge suppression.                  the oscillator, which is evaluated by a trigger stage to activate
                                                                    the output signal. When the magnet moves out of the
The reed switch is very sensitive to interference from other        response travel range, the oscillator current returns to its
nearby magnetic fields or electromagnets with field strength        normal (idling) value and the triggering stage will deactivate
greater than 0.16 mT (T = Tesla). If it is to be used in such       the output signal.
conditions, appropriate shielding must be installed.
                                                                    This type of sensor is not actuated by the proximity of most
Disadvantages of using a reed switch sensor include contact         metallic objects, but its characteristics may be affected by
bounce and limited device life due to the mechanical element        nearby ferromagnetic materials.
(reed switch).




856                                                                                                               Subject to change
Magnetically Actuated Proximity Sensors
Switching Characteristics

                                             When inductive loads are switched, a high voltage peak occurs when the
  Protective circuit for Type SME            contacts open. For this reason, protective circuitry must be provided for the
                                             proximity switch.
                                             The protective circuitry may consist of either a suitable RC circuit or a
                                             corresponding diode or varistor (see circuit diagrams). The electrical values of
                                             these components depend on the downstream operating elements (e.g., relays,
                                             etc.).
                                             If a relay or auxiliary switch is to be shifted, specifications regarding the SME-1
                                             and relay or auxiliary switch must be strictly observed.
                                             Caution:
                                             The inrush power of a relay or auxiliary switch is several (8-10) times greater
                                             than the holding power. The inrush power should therefore be used as a
                                             guideline.
                                             Note:
                                             Cylinders with magnetically actuated proximity switches should not be used
                                             where strong magnetic fields are present (e.g. resistance welding machines).
  Installation
  The distance between proximity switches
  and the nearest outer wall of a magnetic
  cylinder should be at least 2.36 in / 60
  mm unless magnetic shielding is
  provided (applies for all proximity
  switches).




Subject to change   (Ref. 3/1-7) (97/98)                                                                                  857
Magnetically Actuated Proximity Sensors
Functions

                                                  Type SMEO
 Operating Principles                             Reed switch not
 Electrical reed switch - Type SMEO               actuated; switch
 The reed switch is molded in a bakelite          contacts are open.
 case. When the switch enters a magnetic
 field (e.g. a permanent magnet on a
 cylinder piston), the contacts are closed,
 and the switch provides an electrical
 signal.



                                                  When switch enters
                                                  a magnetic field,
                                                  switch contacts are
                                                  closed.




                                                  1 Permanent magnet
                                                    on cylinder piston




 Pneumatic reed switch -                          Type SMPO-1-H-B
 Type SMPO-1-H-B                                  Reed switch is not
 In principle, the reed switch resembles an       actuated; reed
 airgate, in which a reed continuously            interrupts air flow
 interrupts the airflow of an input signal (P).   of P.
 When the switch enters a magnetic field
 (e.g. a permanent magnet on a cylinder
 piston), the reed is attracted and opens a
 passage. The airstream is released, and a
 signal is produced at the output (A).



                                                  Reed is attracted by
                                                  a magnetic field; air
                                                  flows from P to A.




                                                  1 Reed
                                                  2 Permanent magnet
                                                    on cylinder piston
                                                  3 Shield tube PL-9




 Solid State Proximity Switch - Type SMTO
 The proximity switch consists of a
 contactless solid state inductive switch.
 When the switch enters a magnetic field
 (e.g. a permanent magnet on a cylinder
 piston), a change in the electrical current
 state occurs in the switch. An amplifier
 converts the current change to an output
 signal.



858                                                                       (Ref 3/1-6) (97/98)   Subject to change
Magnetically Actuated Proximity Sensors
Ordering Information


All Festo products can be ordered from your local Festo Distributor or from Festo Regional Centers.
A Festo Order Number consists of a Part No. and a Type Code, as described here:


Part No.                          Type


      152742                       S M T O – 4 U – P S – S – L E D – 2 4 – B
Part No.’s are listed on
pages 863-864 and on
sensor description pages.




  Function                                                                                                             Voltage Rating
  SM = Sensor, Magnetically Actuated                                                                                   24 = 24V DC
  CRSM = Corrosion-Resistant Sensor,                                                                                   230 = 230V, AC or DC
          Magnetically Actuated
                                                                                                LED Indication
  Output Signal                                                                                 LED = Integral LED
  E = Electrical                                                                                No letters = LED not incorporated
  T = Inductive
  TS = Inductive, protected against electro-
                                                                                                 Connection
       magnetic interference from welding
                                                                                                 K = Integral cable
       operations                                                                                S = Plug
  P = Pneumatic

  Mounting Style                                                                                Design Feature
  O = Without mounting bracket                                                                  SQ = Lateral plug
  No letter = With integral mounting bracket                                                    SL = In-line plug
                                                                                                KQ = Lateral cable
                                                                                                KL = In-line cable
  Sensor Series                                                                                 PS = PNP circuitry
  1 = Standard                                                                                  NS = NPN circuitry
  2 = Heavy duty                                                                                S6 = Heat resistant
  3 = Dovetail groove                                                                           S9 = Stainless steel
  4 = Cylinder barrel
  4U = “U” shape design, cylinder barrel
  8 = Sensor groove


Refer to pages 863-864 to match cylinders with proximity sensors and mounting brackets.




   Ordering Example 1
   For an installation which requires (a) two magnetically actuated, 24V DC electric output proximity sensors for a cylinder with sensor groove,
   with LED indicators and attached lateral cable, order:

         Item          Qty       Part No.               Type
           a            2        161752                 SME-8C-LQ-LED-24


   Ordering Example 2
   For an installation which requires (a) two magnetically actuated, inductive proximity sensors for a cylinder with sensor groove, PNP output,
   with 0.98 ft / 0.3 m long cable and plug, and (b) angle sockets with 16.4 ft / 5 m long cable for wiring to the sensors, order:

         Item          Qty       Part No.               Type
           a            2        150864                 SMT-8-PS-S-LED-24
           b            2        159425                 SIM-M8-3WD-5-PSL-PU




Subject to change                                                                                                                             859
Magnetically Actuated Proximity Sensors
Overview


 Sensors for Round Barrel ISO Standard Cylinders                                    Sensors for Cylinders with
               Without Mounting Bracket *                                            Integral Sensor Groove

  For Cylinder Types:
  ESNU-...-A       DSNU-...-A        DSNUL-...-A                        For Cylinder Types: See page 864
  SLE with a piston dia. of 16 and 25 mm




                           Electric
  with integral cable             with plug                                                     Electric
  SMEO-4-K-LED-24-B               SMEO-4-S-LED-24-B
  SMEO-4-K-LED-230                                                       with molded 3-wire cable       with 3-wire cable / plug
                                                                         8.2 ft / 2.5 m long            0.98 ft / 0.3 m
                         Inductive                                       SME-8-K-LED-24                 SME-8-S-LED-24
                                                                         SME-8-K-LED-230                with Plug
  with integral cable             with plug                              SME-8-O-K-LED-24               SME-8C-SL-LED-24
  PNP output:                     PNP output:                            SME-8-K-24-S6                  SME-8C-SQ-LED-24
  SMTO-4-PS-K-LED-24              SMTO-4-PS-S-LED-24-B                   SME-8C-KL-LED-24               with 2-wire
  NPN output:                     NPN output:                            SME-8C-KQ-LED-24               SME-8C-KL-LED-230
  SMTO-4-NS-K-LED-24              SMTO-4-NS-S-LED-24-B                   with in-line plug              SME-8C-KQ-LED-230
                                                                         SME-10-KL-LED-24               SME-8C-KQ-24-S6
                                                                         SME-10-SL-LED-24
                                                                         SME-10-KQ-LED-24
                                                                         SME-10-SQ-LED-24

                                                                                               Inductive
                           Electric
                                                                         with molded 3-wire cable       with 3-wire cable / plug
  SMEO-4U-K-LED-24                SMEO-4U-S-LED-24-B                     8.2 ft / 2.5 m long            0.98 ft / 0.3 m
  SMEO-4U-K-LED-230                                                      PNP output:                    PNP output:
                                                                         SMT-8-PS-K-LED-24              SMT-8-PS-S-LED-24
                         Inductive                                       SMT-10-PS-KL-LED-24            SMT-10-PS-SQ-LED-24
                                                                         SMT-10-PS-KQ-LED-24            SMT-10-PS-SQ-LED-24
  with integral cable             with plug
  PNP output:                     PNP output:                            with molded 3-wire cable       with 3-wire cable / plug
  SMTO-4U-PS-K-LED-24             SMTO-4U-PS-S-LED-24                    NPN output:                    NPN output:
  NPN output:                     NPN output:                            8.2 ft / 2.5 m long            0.98 ft / 0.3 m
  SMTO-4U-NS-K-LED-24             SMTO-4U-NS-S-LED-24                    SMT-8-NS-K-LED-24              SMT-8-NS-S-LED-24
                                                                         SMT-10-NS-KL-LED-24            SMT-10-NS-SL-LED-24
                                                                         SMT-10-NS-KQ-LED-24            SMT-10-NS-SQ-LED-24
      Sensors for Corrosion Resistant Cylinders
               Without Mounting Bracket **

  For Cylinder Types:
  CRDNG       CRDNGS         CRDSNU        CRDSW       CRDG




                                                                         protected against interference from welding operations
                                                                         PNP Output:
                                                                         SMTSO-8E-PS-M12-LED-24
                                                                         NPN Output:
                                                                         SMTSO-8E-NS-M12-LED-24
  Electric Sensor, Corrosion and Acid Resistant
  CRSMEO-4-K-LED-24




* For mounting brackets see pages 865-866.         ** For corrosion and acid resistant mounting brackets see page 887.

860                                                                                                               Subject to change

				
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