Manual

112
DXi User Manual
Appendix C: Hardwired Communication Troubleshooting
OUT+ ≈ 3.2K ohm
IN- ≈ 3.1K ohm, Mega ohms or Open Circuit
IN+ ≈ 3.2K ohm
A lower than expected resistance value for any of the measurements in Test 3,
are indicative of a ground leak or short in the communication wire. Additionally,
resistance values greater than 4K ohm but less than 1Mega ohm are suspect of
ground leaks.
Test 4
Power down the suspect controller, upstream controller and downstream controller.
Disconnect the communication cable from the suspect controller, for both the "IN"
and "OUT" connections.
Using a multi meter, make a resistance measurement between the disconnected "IN
+" and "IN -" field wire. Repeat the resistance measurement for the "OUT +" and
"OUT -" field wire.
The resistance value for the two measurements should be approx. 255 ohms.
A lower than expected resistance value are indicative of a ground leak short in the
communication wire.
A higher than expected resistance value is indicative of poor splices or incorrect/
poor quality cable.
An extremely high or open circuit value is indicative of a severed wire.
Test 5
Swap DXi-COM-BOARD, Timer Module (aka TM), and Interfacing cable between
TM and COM board with known good hardware for both the suspect controller and
upstream controller. Disconnect the communication cable "OUT" connections, if
any, of the suspect controller.
Exercise large communication to the controller from Sentinel WMS and monitor the
controller communication diagnostic screen, communication board indication LEDs,
and generation of communication alerts.
Failure to observe normal operating behavior is indicative of a field wiring issue.