Error Messages; Sensors And Communication Errors Of The Scmi-01.4 Module - Sinclair SCMI-01.4 User Manual

6. ERROR MESSAGES

6.1. Sensors and Communication Errors of the SCMI-01.4 Module

During its operation, the SCMI-01.4 module tests the connection of the T1 & T2 resistance
thermometers, and in the autonomous pressure (evaporation temperature) control mode, it
also tests the connection of the pressure sensor to the input 4-20mA. Besides that, it also
tests the communication with the external unit. The module checks the electrical resistance
of both temperature sensors, and if some limit values are detected, it sends a command to
the outdoor unit to gradually stop the compressor. At the same time, it displays the
corresponding error message on the display to distinguish short/open circuit of the
temperature sensor. Errors are indicated in the following sequence. The possible error of the
T1 thermometer will be displayed first, and the next error may be displayed only after fixing
the previous error. Example: Open circuit of the T1 thermometer:
Error T1
Open
Only after fixing this error, the next error, such as a short circuit of the T2 thermometer, may
appear:
Error T2
Short
If both thermometers are functioning properly, the short/open circuit of the pressure sensor
connected to the current input 4-20mA may be indicated next. In addition, a low-pressure
error on the suction side of the outdoor unit compressor may appear.
Error P
Low
Also, in this case, the SCMI-01.4 module sends a command to stop the outdoor unit
compressor; the operation will resume when the pressure exceeds the minimum allowed
value.
If the communication between the active SCMI-01.4 module and the outdoor unit is
interrupted (the module is switched on and the demanded compressor output is greater than
30% in the controlled mode), this status is after about 20 seconds indicated on the display
as:
Err.comm
Disconnected
In this case, it is necessary to check for broken or swapped communication wires that
connect the SC-1 & SC-2 terminals of the SCMI-01.4 module to the corresponding terminals
of the outdoor unit.
If the power and communication cables are placed side by side, this may cause
interference to the communication line, resulting in interrupted signalling of speed or status of
the compressor, fan and expansion valve. In this case, you must use a shielded
communication cable and connect its shielding with the protective wire of the outdoor unit
(connect the cable shield to the ground of the outdoor unit) to eliminate this problem.
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