DSP-100 User Manual
Page 7 of 25
DSP100_MAN_A
4.
Features and Functions
Detector Reset
When any of the 6-position DIP switches (and the 12 DIP switches on the timing version) are changed, the detector
will perform a detector wide reset. Depending how the internal jumper (J2) is set, the LEDs will blink differently.
If the jumper is installed indicating fail-safe operation, both LEDs will blink 500 milliseconds on and off for two
seconds. If the jumper (J2) is not installed indicating fail-secure operation, the LEDs will flash at 50 milliseconds
on and 50 milliseconds off rate for two seconds before returning to their normal states. The detector will not
output any detections during this two second reset period. If a prior loop fault is being displayed it will be cleared.
If a vehicle is over the loop during the reset period it will not be detected.
Presence Detection
If DIP switch 4 (labeled PULSE) is off, the detector will operate in the presence detection mode. The Delay and
Extend features may modify the output behavior. Once activated, the output will remain activated as long as a
vehicle is detected over the loop. After four minutes of continuous detection, the detector will begin to slowly
retune the detector with the goal of tuning out the vehicle that is stalled or parked on the loop over a relatively
long time. The retuning process takes about an hour to complete when tuning out a vehicle detection of 1
% ΔL/L
.
When the retuning process is complete, any loop area that vehicles can still travel over will still detect a vehicle
as expected. Once the vehicle leaves, the detector will recover from the retuning process within 1 second.
Pulse Detection
If DIP switch 4 (labeled PULSE) is on, the detector will operate in the pulse mode (Pulse on Entry). The pulse
generated by the output will be 125 milliseconds long. The output will follow any programmed Delay time, but
any Extend time will be ignored. If the vehicle remains on the loop detection area for two seconds, the detector
will automatically retune. Thus, any increase in signal strength (decrease in inductance) that exceeds the selected
sensitivity will generate an additional output pulse.
Figure 3: Output with No Delay or Extension
Fail-safe vs Fail-secure
Vehicle detectors can be operated in one of two modes: fail-safe or fail-secure. In general, a fail-safe detector will
activate the output when the loop circuit is failed. This is useful on most calling detectors, stop bar detectors, and
safety loops. Fail-safe is used in applications where it is important to not have an output active if the loop circuit
