Nortech PD17x, User Manual

Page: 12 / 31

307UM0100_01 May 2016 PD17x User Manual Page 12 of 31
4.3 Types of Outputs
The PD17x has one relay set to output presence on detect and the other to output a pulse on detect or undetect. When
a relay is configured as a presence output, it will produce a continuous output during the presence of a vehicle over the
inductive loop. When configured as a pulse output, the relay will output a pulse according to the pulse duration setting
and trigger event. The trigger event may be set to be either of the following:

Pulse on detect – the detector will give a pulse output on detection of a vehicle.

Pulse on un-detect – the detector will give a pulse output as the vehicle is un-detected.
The Pulse relay automatically operates in fail secure mode, while the presence output relay can be set to operate as fail
safe or fail secure.
Presence Relay Programming
Fail Secure Fail Safe
Relay
N/C N/O N/C N/O
Un detect Open Closed Closed Open
Detect Closed Open Open Closed
Fault Open Closed Open Closed
Power Off Open Closed Open Closed
Figure 5. Presence Relay output configuration options
Pulse Relay
N/O N/C
Idle Open Closed
On Event Closed Open
Fault Open Closed
Power Off Open Closed
Figure 6. Pulse Relay output configuration options
In fail-safe, the output is the same in detect as it is with no power applied to the unit. Either a valid detect situation, or
a power failure / fault will provide a signal. In fail-secure, the output is the same in un-detect as it is with no power
applied to the unit. Only a valid detect situation will provide a signal.
4.4 Response times
The response time of the detector is the time taken from when a vehicle moves over the loop to when the detector
gives an output.
The response times of the PD17x have been adjusted to prevent false operation in electrically noisy environments, but
retain adequate response to vehicles in parking and vehicle access control applications.
The response time will be proportional to the level of sensitivity, the level of the detect and the speed of the vehicle. In
other words, a fast moving large detect will respond quicker than a slow moving small detect. Also, if the sensitivity is
set very low, the point at which it crosses the threshold will be later than higher sensitivity settings. At maximum
sensitivity however, the response time is slower than other sensitivity levels to prevent false operation from noisy
environments.