Position Monitoring Devices

Choosing Position Monitoring Devices components

Position monitoring is about reporting discrete state, not measuring continuous position. The selection comes down to the actuation method (mechanical lever, plunger, magnetic, non-contact), the contact configuration (SPDT, DPDT), and the integration with the supervisory system (hardwired NO/NC, M12 connector to PLC, AS-Interface bus, IO-Link).

Specs to confirm before ordering:

Sensing technology: mechanical limit switch (lever, roller, plunger), magnetic switch (T-slot or C-slot reed switch for cylinders), inductive proximity for end-of-stroke, or rotary-shaft position monitor
Actuation: cam, roller-plunger, top-mount lever, side-rotary, fork lever
Contact configuration: SPDT 1NO+1NC, DPDT 2NO+2NC, snap-action vs. slow-action
Contact rating at the operating voltage and load type
Mechanical and electrical life
Conduit / cable / connector style
IP rating — IP66/67 standard, IP69K for washdown
For valve position monitors: visual indicator dome, NEMA enclosure rating, ATEX certification for hazardous areas, fieldbus output (AS-i, Profibus, Profinet, Foundation Fieldbus)
For pneumatic cylinder switches: T-slot vs. C-slot, reed (mechanical contact) vs. solid-state (no moving parts, longer life)

Common gotchas: T-slot and C-slot cylinder switches are not interchangeable — they fit different cylinder body extrusions. Reed-type magnetic switches wear out from contact arcing on inductive loads (solenoid coils); use solid-state switches for high-cycle applications. Valve position monitors with hazardous-area certification (ATEX/IECEx) require specific cable glands and wiring methods; substituting a non-rated unit voids the area classification. Limit switches with snap-action contacts (microswitch-style) have different actuation force than slow-action; replacing one with the other changes the cam profile needed.

Typical applications: cylinder end-of-stroke confirmation on pneumatic and hydraulic actuators, valve open/closed position to the SCADA system (water, oil and gas, chemical), conveyor end-of-travel limits, machine-guard position monitoring (non-safety variants), and overhead crane travel limits.

For obsolete position monitoring devices, send the OEM part number for a sourcing quote.

Do you stock obsolete limit switches and valve position monitors?

Yes. Discontinued Allen-Bradley 802 codes, retired Honeywell MICRO SWITCH, end-of-life Topworx D-series first generations, and earlier ASCO ValPlus are sourced through our supplier network.

T-slot vs. C-slot pneumatic cylinder switches — what's the difference?

The cylinder body extrusion shape. T-slot has a T-shaped channel, C-slot has a C-shaped channel. The switch body is shaped to fit one and not the other. Verify which slot your cylinder has before ordering.

Reed switch vs. solid-state — does it matter?

Reed switches use mechanical contacts and have finite life on inductive loads (a few million operations typically). Solid-state Hall-effect switches have no contacts and effectively unlimited life. Use solid-state in high-cycle applications.

Will an old-style valve position monitor work with my new PLC?

Hardwired NO/NC contact-style monitors work with any PLC discrete input. AS-i or fieldbus monitors need the corresponding network on the PLC side. We will state the interface type on each listing.

Are hazardous-area ratings preserved on surplus units?

Yes — the OEM certification (ATEX, IECEx, Class I Div 1/2) is the property of the unit when manufactured. Surplus units retain that certification. We do not modify devices.

What is the warranty?

12-month functional warranty. Contact wear from extended high-cycle inductive switching, mechanical lever damage, or operation outside rated environment is not covered.

Position Monitoring Devices

Pepperl+Fuchs INX360D-F99-B16-V15 Tilt and Inclination Sensor

Pilz 544011 Safety Sensor

Pilz 544012 Safety Sensor

Pilz 544021 Safety Sensor

Pilz 544022 Safety Sensor

Pilz 570300 Safety Sensor

Pilz 570301 Safety Sensor

Pilz 570302 Safety Sensor

Pilz 570303 Safety Sensor

Pilz 570310 Safety Sensor

Pilz 570311 Safety Sensor

Pilz 570312 Safety Sensor

Pilz 570313 Safety Sensor

Pilz 570314 Safety Sensor

Pilz 570315 Safety Sensor

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