Instructions for 9405 & 9409 Dual-Channel Loop Detector
These loop detectors are designed to be used with DoorKing vehicular gate operators only and
control two individual loops. The detector plugs into loop detector ports on the gate operator control
board. The detector also employs several automatic and advanced features that will decrease "false"
calls and assist technicians in the field with trouble shooting loop problems. Refer to the LOOPINFO
manual for information on installing in-ground loops.
Sensitivity Boost
The sensitivity boost feature automatically increases the sensitivity of the loop detector when the
detector is tripped by the passage of a vehicle over the loop. This prevents the detector from "losing"
high bed vehicles as they pass over the loop. Boost can be set individually for each loop.
Fast-Trak
When Fast-Trak is turned on, the detector will track slow frequency shifts in the loop twice as fast as
when this feature is turned off. This feature is useful on poor quality loops that drift in frequency. An
indication of this would be when the detector has many "false" calls. Fast-Trak can be set individually
for each loop.
Caution should be exercised when using the Fast-Trak feature. When Fast-Trak is turned ON, it will
cause the presence time of the detector to be about half that of normal. That is to say, the detector
will "tune out" vehicles that are parked on or near the loop about twice as fast as when this feature is
turned off.
For this reason, we recommend that the Fast-Trak feature only be used as a
temporary solution to loop frequency drift problems that are typically (but not always) caused
by the use of poor quality wire in the loop itself
. If excessive frequency drift continues (indicated
by many "false" calls), the loop itself will have to be replaced.
Frequency Measurement
Whenever the detector is powered up, or when the reset switch is pressed, the detector will blink out
the frequency that the loop has tuned to (in KHz) on the CALL LED. Loop 1 will blink its frequency
first followed by loop 2. For example, five blinks - pause - six blinks – pause - five blinks – pause -
two blinks indicates that LOOP 1 has tuned to 56 KHz and LOOP 2 has tuned to 52 KHz.
This automatic frequency measurement is useful in applications where two or more loops and loop
detectors are in close proximity to each other. A common problem with loop detectors "false calling" is
because two or more loops in close proximity to each other are cross talking. Knowing what
frequency the loop has tuned to allows you to reset the frequency on one of the detectors as far from
the other detector as possible.
Loop Monitor
The loop detector constantly monitors the frequency of the loop to determine if the frequency is too
high or too low, or if the loop has opened. When this happens, the detector will LOCK ON and the
loop CALL LED will flash. If the frequency of the loop returns to nominal levels, the detector will
resume normal operation but will continue to flash the CALL LED.
A flashing CALL LED is an indication that a problem exist in the loop itself and that the loop should be
replaced. The CALL LED can be reset by pressing the reset button.
P/N 9405-065 REV C 7/04
