HySecurity SwingSmart DC 20 Installation And Reference Manual page 94

Installing Vehicle Detectors and Loops
Detector Logic
HySecurity recommends that vehicle detectors be used for free open and obstruction sensing logic only.
Because of their slower speeds, closing logic is a poor choice for security gate systems. Since there are several
ways that the gate may be left standing open and because there is a loss of safety, our circuit has not been
designed to accommodate "detect to close" logic.
Loop Diagnostics
The following tests cannot guarantee a functioning loop, but failure of either test means that the loop is
definitely suspect, even though it may still be functioning at the time.
1. Test the resistance of the loop and lead-in wire. It should not exceed 4 Ohms.
2. Test the resistance between the loop and earth ground with a 500V Megohm meter. It should be 100
Megohms or more. Loops may function at 10 Megohms or less but will not be reliable (e.g. when the
ground is wet from rainfall). Low resistance indicates broken or moisture saturated insulation. This is
common if inappropriate wire insulation has been used.
Schematics for Swing Gate Loop Layout are shown in Figure 6-7 and Figure 6-8.
6-8 SwingSmart - Installation, Operation and Maintenance Manual Revision A