Linear Pro Access FM139 Exit Wand Vehicle Sensor - 50 Ft Cable
The FM139 exit wand is a wired driveway vehicle sensor used to open a gate automatically as a vehicle leaves the property. The sensor is buried beside the driveway and detects iron-based metal in motion, then sends a short relay pulse to the operator control board. It is a practical choice when the operator cabinet is close enough for a 50 ft cable run and the installer wants a hardwired sensor instead of a wireless transmitter. The FM139 is often used on residential, ranch, farm, and light commercial gate systems where hands-free exit is needed for residents, deliveries, or service vehicles. Correct placement is just as important as the model number: the wand should be stationary, buried at the proper depth, located close enough to the driveway for detection, and kept far enough from the moving gate to prevent unwanted activation. It does not provide obstruction protection and should not be confused with a loop detector safety system.
Compatible With
- Linear Pro Access FM139 wired exit wand applications
- GTO FM139 and Mighty Mule FM138-style 50 ft exit wand applications
- Automatic gate operators with compatible dry-contact exit/open inputs
- Linear / GTO swing and slide operators when wiring and voltage are supported
- Mighty Mule and related GTO low-voltage systems when matched by control input
- Residential, agricultural, ranch, and light commercial gate exit activation
- Related cable-length family: FM139 50 ft, FM140 100 ft, FM141 150 ft, FM141-250 250 ft
Features and Specifications
| Manufacturer | Linear / GTO |
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| Product Type | Wired vehicle exit wand |
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| Part Number | FM139 |
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| Application | Exit-side vehicle activation |
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| Cable Length | 50 ft |
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| Detection Type | Electromagnetic moving-metal detection |
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| Voltage | Commonly 8-26 VAC or 11-30 VDC |
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| Output | Dry contact relay pulse |
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| Safety Monitoring | Not a safety device |
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| Notes | Match cable length and control-board input before ordering |
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Also Known As / Related Part Numbers
- FM139
- GTO FM139
- Linear FM139
- Mighty Mule FM138 related reference
- FM139-P
- 50 ft exit wand
- Related models: FM140, FM141, FM141-250
- Related service board: REWPOTPCB-01
Technician Note
Use the FM139 only when the 50 ft cable length fits the site. Splicing or stretching the cable route can create reliability issues; choose FM140 or FM141 when a longer direct-burial run is needed.
Before Ordering
- Confirm the needed cable length before ordering.
- Verify the gate operator has a compatible open/exit input.
- Plan burial depth, distance from driveway edge, and distance from the moving gate.
- Confirm the sensor will not be used as a safety device.
- Check whether the existing wand failure is actually a control board, wiring, or power issue.
Important Ordering Warnings
- Do not rely on this device to reverse a closing gate. It is not a monitored safety device.
Professional Advisory
Exit wands should be installed so they command the gate open without creating unsafe automatic movement. Use a qualified technician when the control terminals are unclear or required safety devices are missing.
Product Questions and Answers
What cable length does the FM139 include?
FM139 is the 50 ft wired exit wand version. FM140 and FM141 are commonly used for longer cable runs.
Does the FM139 detect people?
No. It is intended to detect moving iron-based vehicles or metal mass, not pedestrians.
Can FM139 be used as a safety sensor?
No. It is an exit activation device only and should not replace photo eyes, safety edges, or required entrapment protection.
What output does the FM139 provide?
It provides a dry-contact relay pulse to a compatible gate operator input.
What is a common symptom of a bad exit wand?
Common symptoms include no automatic opening when vehicles exit, nuisance openings, or sensitivity that cannot be adjusted correctly after checking wiring and placement.
