Magnetically ActuatedProximity Sensors

853Subject to change

Subject to change

Magnetically Actuated Proximity SensorsContents

Features and Benefits ............................................. 855

Switching Characteristics .........................................857

Functions ..................................................................858

Ordering Information .........................................859

Overview...................................................................860

Mounting Bracket Overview .....................................865

Mounting Bracket Dimensions ..................................866

Sockets for Sensors with 8 mm Push-In or M8 x 1 Threaded Plug........................................867

Sockets for Sensors with M12 x 1 Threaded Plug....868

DUO Cables for Sensors ..........................................869

Sensors for Cylinders with Sensor GrooveElectric Proximity Sensors, Type SME-8-... .............870

Inductive Proximity Sensors, Type SMT-8-... ..........871

24 Volt Electric Proximity Sensors,

Type SME-8C-...-24 ..........................................872

230 Volt Electric Proximity Sensors,

Type SME-8C-...-230 ........................................872

Electric Proximity Sensors,

Type SMEO-8E-... .............................................874

Inductive Proximity Sensors,

Type SMTO-8E-... .............................................876

24 Volt Electric Proximity Sensors,

Type SMTS-8E-... .............................................877

24 Volt Electric Proximity Sensors,

Type SME-10-...-24 ...........................................878

Inductive Proximity Sensors, PNP Output,

Type SMT-10-PS-...-24 .....................................880

Inductive Proximity Sensors, NPN Output,

Type SMT-10-NS-...-24 .....................................880

Sensors for Cylinders with Dovetail SensorGrooveElectric Proximity Sensors

Type SME-3-... ..................................................882Inductive Proximity Sensors

PNP Output, Type SMT-3-PS- ..........................883NPN Output, Type SMT-3-NS-...........................883

Sensors for Round Barrel ISO Standard

CylindersElectric Proximity Sensors

Type SMEO-4-... ...............................................884

Inductive Proximity Sensors

Type SMTO-4-... ...............................................884

854

Electric Proximity Sensors, Corrosion and

Acid Resistant, Type CRSMEO-4-... .................886

Accessories, Corrosion and Acid Resistant .............887

Electric Proximity Sensors, U-Shape,

Type SMEO-4U-... .............................................888

Inductive Proximity Sensors, U-Shape,

Type SMTO-4U-... .............................................889

Cylinders for Tie-rod Cylinders and Cylinders

with Integral Sensor RailElectric Proximity Sensors

With Cable, Type SMEO-1-... ............................891

With Plug, Type SMEO-1-S-... ..........................892

Inductive Proximity Sensors

PNP Output, Type SMTO-1-PS-... ....................893

NPN Output, Type SMTO-1-NS-... ....................893

Electric Proximity Sensors

With Cable, Type SME-1-... ..............................894

With Plug, Type SME-1-S-... .............................895

Type SMTO-6-PS-S-LED-24..............................898

Type SMTSO-1-PS-S-LED-24 .......................... 899

Heavy Duty Electric Proximity Sensors

Type SMEO-2 ...................................................896

Type SMEO-2-LED-24... .................................. 896

Type SME-2-LED-24... ......................................896

Inductive Sensors

Type SMTO-6-PS-S-LED-24 .............................898

Type SMTSO-1-PS-S-LED-24 ..........................899

Pneumatic Reed SwitchType SMPO-1-H-B .............................................900

All-Pneumatic Cylinder SwitchType SMPO-8E ..................................................901

Hall Effect Sensors for GrippersType SMH-S1-... ................................................902

Sensors for Actuators with Threaded MountingHolesInductive Proximity Sensors, Threaded Body Design

Type SIEN-M5B-... ............................................908

Type SIEN-M8B-... ............................................910

Sensor AccessoriesSensor Tester, Type SM-TEST-1.......................912

855Subject to change

Magnetically Actuated Proximity SensorsFeatures and Benefits

Features:

■ Rapid function monitoring and fault detection reduces downtime

■ Easily interfaced to programmable controllers

■ Inductive NPN or PNP, electrical or pneumatic outputs

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

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

■ Eliminates cumbersome external limit switches

■ AC or DC or pneumatic operation

Operation:

Electrical Proximity SensorsType SME-..., SMEO-...The reed switch is molded in abakelite case. When the switch entersa magnetic field (e.g. a permanentmagnet on a cylinder piston), thecontacts are closed, and the switchprovides an electrical signal.

Inductive Proximity SensorsType SMT/SMTOA magnetic field changes theelectrical current state of thiscontactless, solid state inductiveswitch. The resulting current changeis amplified to produce an outputsignal.

Pneumatic Reed SwitchType SMPO-1-H-BSimilar to an airgate, a reedcontinuously interupts airflow. Amagnetic field opens the reed. Theairflow produces a pneumatic output.

Note: Do not install in areas with highmagnetic fields (e.g. resistance-weldingmachines).

Magnetically Actuated Proximity Sensors offer Sensing VersatilityMagnetically actuated sensors are primarily designed for use oncylinders manufactured with sensing capability (i.e. permanent magneton the circumference of the cylinder piston), but many of them can alsobe used in other areas where the proximity to a magnetic field is to be acriterion for producing electrical control signals.

When a pneumatic cylinder’s design includes a permanentmagnet on the piston, proximity sensors attached to theoutside of the cylinder tube can be used to signal when thecylinder is at either end stop position and, depending on theminimum spacing requirements of the sensors used, at oneor more intermediate positions. Three types of sensors aresuitable for use in this application.

Reed Switch

When the piston’s magnet enters the response travel rangeof the sensor, the magnet’s field causes the contacts of thereed switch inside the sensor to close, completing the circuitpath to illuminate the LED (if present) and activate the outputsignal. When the magnet moves out of the response travelrange, the reed switch opens again; the LED extinguishesand the output signal returns to its inactive (i.e. “off”) state.

Built-in protective circuits in a reed switch proximity sensorinclude current limiting and RC surge suppression.

The reed switch is very sensitive to interference from othernearby magnetic fields or electromagnets with field strengthgreater than 0.16 mT (T = Tesla). If it is to be used in suchconditions, appropriate shielding must be installed.

Disadvantages of using a reed switch sensor include contactbounce and limited device life due to the mechanical element(reed switch).

856 Subject to change

Magnetically Actuated Proximity SensorsTechnical Data

S

Inductive-Magnetic

The inductive-magnetic proximity sensor is much like anormal inductive proximity sensor, using an internal LCoscillating circuit. But rather than using a half-shell coredesign to direct a magnetic field outward, this sensor has aclosed-shell core design which does not emit anelectromagnetic field. When the piston’s magnet enters theresponse travel range of the sensor, the magnet’s fieldcauses saturation of the coil material of the oscillator’s coil.This produces a variation in the amount of current drawn bythe oscillator, which is evaluated by a trigger stage to activatethe output signal. When the magnet moves out of theresponse travel range, the oscillator current returns to itsnormal (idling) value and the triggering stage will deactivatethe output signal.

This type of sensor is not actuated by the proximity of mostmetallic objects, but its characteristics may be affected bynearby ferromagnetic materials.

S

S

No Output Signal

Sensor

a) Sensor not actuated

b) Sensor actuated

Sensor

Active Output Signal

Magnetically Actuated Proximity SensorsSwitching Characteristics

857Subject to change (Ref. 3/1-7) (97/98)

Protective circuit for Type SME

Installation

The distance between proximity switchesand the nearest outer wall of a magneticcylinder should be at least 2.36 in / 60mm unless magnetic shielding isprovided (applies for al l proximityswitches).

When inductive loads are switched, a high voltage peak occurs when thecontacts open. For this reason, protective circuitry must be provided for theproximity switch.

The protective circuitry may consist of either a suitable RC circuit or acorresponding diode or varistor (see circuit diagrams). The electrical values ofthese 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-1and relay or auxiliary switch must be strictly observed.

Caution:

The inrush power of a relay or auxiliary switch is several (8-10) times greaterthan the holding power. The inrush power should therefore be used as aguideline.

Note:

Cylinders with magnetically actuated proximity switches should not be usedwhere strong magnetic fields are present (e.g. resistance welding machines).

858 (Ref 3/1-6) (97/98) Subject to change

Magnetically Actuated Proximity SensorsFunctions

Operating Principles

Electrical reed switch - Type SMEOThe reed switch is molded in a bakelitecase. When the switch enters a magneticfield (e.g. a permanent magnet on acylinder piston), the contacts are closed,and the switch provides an electricalsignal.

Pneumatic reed switch - Type SMPO-1-H-BIn principle, the reed switch resembles anairgate, in which a reed continuouslyinterrupts the airflow of an input signal (P).When the switch enters a magnetic field(e.g. a permanent magnet on a cylinderpiston), the reed is attracted and opens apassage. The airstream is released, and asignal is produced at the output (A).

Solid State Proximity Switch - Type SMTOThe proximity switch consists of acontactless solid state inductive switch.When the switch enters a magnetic field(e.g. a permanent magnet on a cylinderpiston), a change in the electrical currentstate occurs in the switch. An amplifierconverts the current change to an outputsignal.

Type SMEOReed switch notactuated; switchcontacts are open.

When switch entersa magnetic field,switch contacts areclosed.

1 Permanent magnet on cylinder piston

Type SMPO-1-H-BReed switch is notactuated; reedinterrupts air flow of P.

Reed is attracted bya magnetic field; airflows from P to A.

1 Reed2 Permanent magnet

on cylinder piston3 Shield tube PL-9

SP

Magnetically Actuated Proximity SensorsOrdering Information

Subject to change 859

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:

Voltage Rating 24 = 24V DC230 = 230V, AC or DC

LED IndicationLED = Integral LED No letters = LED not incorporated

Mounting StyleO = Without mounting bracketNo letter = With integral mounting bracket

Sensor Series1 = Standard2 = Heavy duty3 = Dovetail groove4 = Cylinder barrel4U = “U” shape design, cylinder barrel8 = Sensor groove

Output SignalE = ElectricalT = InductiveTS = Inductive, protected against electro-

magnetic interference from welding operations

P = Pneumatic

FunctionSM = Sensor, Magnetically ActuatedCRSM = Corrosion-Resistant Sensor,

Magnetically Actuated

S152742 M T O – 4 U – – S – L E D – 2 4 – B

Ordering Example 1For 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 2For 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-24b 2 159425 SIM-M8-3WD-5-PSL-PU

Part No. Type

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

ConnectionK = Integral cableS = Plug

Design FeatureSQ = Lateral plugSL = In-line plugKQ = Lateral cableKL = In-line cablePS = PNP circuitryNS = NPN circuitryS6 = Heat resistantS9 = Stainless steel

Part No.’s are listed onpages 863-864 and on sensor description pages.

Sensors for Round Barrel ISO Standard CylindersWithout Mounting Bracket *

Electric

with integral cable with plugSMEO-4-K-LED-24-B SMEO-4-S-LED-24-BSMEO-4-K-LED-230

Inductive

with integral cable with plugPNP output: PNP output:SMTO-4-PS-K-LED-24 SMTO-4-PS-S-LED-24-BNPN output: NPN output:SMTO-4-NS-K-LED-24 SMTO-4-NS-S-LED-24-B

Electric

SMEO-4U-K-LED-24 SMEO-4U-S-LED-24-BSMEO-4U-K-LED-230

Inductive

with integral cable with plugPNP output: PNP output:SMTO-4U-PS-K-LED-24 SMTO-4U-PS-S-LED-24NPN output: NPN output:SMTO-4U-NS-K-LED-24 SMTO-4U-NS-S-LED-24

Sensors for Corrosion Resistant CylindersWithout Mounting Bracket **

For Cylinder Types:CRDNG CRDNGS CRDSNU CRDSW CRDG

Electric Sensor, Corrosion and Acid Resistant

CRSMEO-4-K-LED-24

Sensors for Cylinders with Integral Sensor Groove

Electric

with molded 3-wire cable with 3-wire cable / plug8.2 ft / 2.5 m long 0.98 ft / 0.3 mSME-8-K-LED-24 SME-8-S-LED-24SME-8-K-LED-230 with PlugSME-8-O-K-LED-24 SME-8C-SL-LED-24SME-8-K-24-S6 SME-8C-SQ-LED-24SME-8C-KL-LED-24 with 2-wireSME-8C-KQ-LED-24 SME-8C-KL-LED-230with in-line plug SME-8C-KQ-LED-230SME-10-KL-LED-24 SME-8C-KQ-24-S6SME-10-SL-LED-24SME-10-KQ-LED-24SME-10-SQ-LED-24

Inductive

with molded 3-wire cable with 3-wire cable / plug8.2 ft / 2.5 m long 0.98 ft / 0.3 mPNP output: PNP output:SMT-8-PS-K-LED-24 SMT-8-PS-S-LED-24SMT-10-PS-KL-LED-24 SMT-10-PS-SQ-LED-24SMT-10-PS-KQ-LED-24 SMT-10-PS-SQ-LED-24

with molded 3-wire cable with 3-wire cable / plugNPN output: NPN output:8.2 ft / 2.5 m long 0.98 ft / 0.3 mSMT-8-NS-K-LED-24 SMT-8-NS-S-LED-24SMT-10-NS-KL-LED-24 SMT-10-NS-SL-LED-24SMT-10-NS-KQ-LED-24 SMT-10-NS-SQ-LED-24

protected against interference from welding operationsPNP Output:SMTSO-8E-PS-M12-LED-24NPN Output:SMTSO-8E-NS-M12-LED-24

Magnetically Actuated Proximity SensorsOverview

Subject to change

For Cylinder Types: See page 864

860

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

For Cylinder Types:ESNU-...-A DSNU-...-A DSNUL-...-ASLE with a piston dia. of 16 and 25 mm