7. Replace the PCB in the Control Unit enclosure.
5.2.14 Remote Display Unit not communicating with the Control Units
In the event of a communications failure between the Remote Display Unit and the Control Unit(s) the
bar graph for the engine will be displayed with a cross through it.
Figure 178 Remote Display Unit Communication Fault
In the event of a communications failure the following steps should be followed:
1. Check the Modbus connections in each Control Unit, ensuring that in each case all four connections
are made to the terminals, A, B, GND and SCN.
If the connections are correctly made go to item 2.
If the connections are incorrect reconnect the cable correctly or if necessary, replace the cable.
2. Check the Modbus connections in the junction box if one has been used to extend the cable from the
Remote Display Unit. Ensure all four connections are made between the two joined cables A, B, GND
and SCN.
If the connections are correctly made go to item 3.
If the connections are incorrect reconnect the cable correctly or if necessary, replace the cable.
3. Check that screened cable has been used for both the Modbus and Power Supply connections to the
Remote Display Unit.
If the cables are correctly made go to item 4.
If the cables are incorrect replace the cable with an approved cable, see section 2.6.
4. Check that screened cable has been used for both the Modbus and Power Supply connections to the
Control Unit.
If the cables are correctly made go to item 5.
If the cables are incorrect replace the cable with an approved cable, see section 2.2
5. Check that the end of line jumpers are installed only in the last Control Unit, see Figure 8.
If the end of line jumpers are correctly configured, go to item 6
If the jumper links are installed in more than one Control Unit remove the links from all except
the last one.
If no jumper links are installed in the Control Unit place jumper links across the end of line pins
in the last Control Unit.
6. Check that the Modbus address is correct in each Control Unit. The Modbus address can be checked
see section 3.1.
In the case of Control Units without a membrane fitted an approved service engineer will be required
to check the Modbus address and to change the address.
If the Modbus addresses are correct, go to item 7.
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