MDE-4318D Competitive Pump and CRIND (CPC) Hardware/Software Start-up and Service Manual · May 2010 Page 51
Communication Issues - Checklist
Troubleshooting Steps
What voltage is present when referencing TP3 on the T20488 Distribution
Board to Chassis?
Note: Test with field wiring at P106 and P107 disconnected.
This must read 0 VDC. If this voltage is not present (or out of specifications), then the T20488
Distribution Board, T19547 Distribution Board, R19262-G2 expansion cable or transformer
may have to be replaced. Troubleshoot each independently until the root cause is identified.
Is an analog voltmeter being used to record the voltage present between
data wires for all fueling positions and CATs?
An analog voltmeter is required for this checklist item as a digital meter will not properly
capture this information. There must be no more than 2-3 VDC present between any pair of
communication wires. If the voltage between an identified pair exceeds this range, it indicates
an issue (faulty electronics, an electrical issue, a wiring issue, and so on) that has to be
investigated at the fueling position itself.
Are other wires present in the conduit that contains the dispenser data
communication wires? If so, identify these wires.
Communication wiring may be affected by Radio Frequency Interference. If any wiring exists
that may potentially introduce Radio Frequency noise, wiring must be relocated to address this
concern.
What wires are present in the wiring trough?
Communication wiring may be affected by Radio Frequency Interference. If any wiring exists
that may potentially introduce Radio Frequency noise, wiring must be relocated to address this
concern.
Are variable speed STP wires in proximity to dispenser data
communication wires?
Variable speed submersible turbine wiring must not be in the same conduit or wiring trough
with communication wires. This will introduce noise that affects communication between the
POS and forecourt. If this wiring is present, communication wiring or STP wires must be
relocated as required, to address this concern. Refer to the manufacturer’s specifications for
additional information.
Are all unused data pairs on the T20488 cut and individually wire
capped?
For RS-485 communication, all unused data pairs must be cut and individually wire capped, if
isolation jumpers are in a “Normal” position. If you fail to do so, it will prevent RS-485
communication, as the loop will be shorted.
If the issue occurs frequently, proceed as follows:
1
Isolate a fueling position using the NORMAL/ISOLATE jumper in the distribution box.
2
Wait for 30 to 45 minutes.
