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VD940 – Sensitivity Adjustable Detector

The 10 pin Molex plug format is commonly found on US gate and barrier control panels for radio receivers as well as loop detectors. Pin connections vary between manufacturers so check for compatability.

The VD940 is a basic detector with a single button for reset. VD940 has the same architecture as the VD922, with 4 sensitivity levels that can be selected using the button.

presence and B for pulse. Output A can be programmed with additional delays. Output B can pulse when the vehicle enters the loop area, pulse when it leaves the area, or presence when the loop fails. This detector could be the only module you ever need to carry!



The VD940 detector will add a new dimension of simplicity to your plug-in detector requirements.  The VD940S has 4 levels of sensitivity which may be changed.  At last a plug-in detector that will operate on any voltage from 10 to 30 volts AC or DC.

It has been specifically designed to handle parking, drive-through and access control applications where solid-state outputs are required for both the detect and fail outputs.  The detector loop inductance should be between 20 and 2000 microhenries.

  • Small profile, perfect for many installations
  • Designed to be cross talk free between other loops
  • Works on any in-ground inductive loop from 20 to 2000 microhenries.
  • Automatically compensates for loop and lead-in sizes
  • Fail safe operation
  • Wide low-voltage operation
  • Separate Power/Fail and Detect LEDs.

This detector has been specifically designed to handle parking, drive-through and access control applications where solid-state outputs are required for both the "Detect" and the "Fail" outputs.

VD940 - click to download

LED Indicators: The green Power LED will be on steady to indicate the detector is operating and powered. The red Detect LED will turn on when a vehicle is over the loop detection area.

Detect Memory: Power interruptions of short duration are ignored.  If power fails for approximately 1 ½ seconds or less the detector “remembers” a vehicle.

Sensitivity and Reset Push Button: The Reset/Sens. button is used for two functions.  A short press and release of the button will reset the detector and the LED's will both flash from 1 to 4 times, indicating the detector's sensitivity level. The detector is shipped from the factory with the sensitivity set at level 3.  If a different sensitivity level is required push and continue to hold the button until the LED's start flashing.  Release the button immediately after the desired number of flashes.  For example, if the sensitivity is to be changed to level 2, push and hold the button until the LED's flash twice then immediately release the button.  The sensitivity level can always be verified by a quick tap on the push button.  This will reset the detector and flash the two LED's indicating the present level.
Level 1 - Very Low
Level 2 - Low
Level 3 - Normal (Factory setting)
Level 4 - High

Loop or Wire Failures: In the case of a loop circuit failure, the green LED flashes slowly (twice per second) for an open loop circuit failure.  The green LED will flash fast (10 times per second) to indicate a shorted loop circuit.

  1. Fail Safe vs Fail Secure: A fail safe detector will output “detect” when the loop circuit is failed.  This is always useful on a safety loop.  On the free exit loop this will keep the gate open until the situation is fixed.  This is useful in applications where it is important to allow traffic flow to continue.  A fail secure detector will never output “detect” when the loop circuit is failed.  This will keep the gate closed.  This is useful in high-security areas or installations where containment is needed.  The DSP-40S is a fail safe detector. Note: Never use a fail secure detector on a safety loop.

Outputs: Solid-state (open transistor collectors) for both detect and fail outputs.  30 mA maximum current sink- transient voltage protected.

Power: 12 to 30 volts DC

Operating Temperature: -35°F to 165°F (-37°C to 74°C)

Size: Height: 2.4" Width: 0.8" Depth: 2.25”

10-position Molex Type 09-48-1104
Mates with many female PCB 0.156” pitch headers in use by some access control devices and gate operators.

1: Loop input
2: Loop input
3: Power* (10 to 30 volts AC or DC)
4: No Connection
5: No Connection
6: Fail output -connects to common for fail.
7: Fail output -connects to common for fail.
8: Detect output -connects to common for detect.
9: Power* (10 to 30 volts AC or DC)
10: Power Common
*Either or both of these pins can be used to supply power to the detector.

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