3BHE033067R0103 GCC960C103 fault finding: 1, suspected analogue output board and card problems, using a multimeter to measure the 4-20mA output signal, the signal is normal! 2, began to suspect that there is a problem with the control signal input of the inverter, replaced by an inverter of the same type, is still the case. 3, with a hand-held signal transmitter to do 4-20mA output signal source, the output signal to the inverter, this inverter start, exclude analog output board and inverter failure.4, thus presumed to be the inverter interference signal conduction to the analog channel due to, in order to verify, in the analog 4-20mA output channel added a signal isolation module TA3012, TA3012 input terminals 5, 6 connected to the analog output module, output Terminals 1 and 2 are connected to the frequency converter, and terminals 3 and 4 are connected to the external 24VDC power supply, and the frequency converter starts up normally.5 From this, it is judged that the root of the problem is still caused by the frequency converter interfering with the analogue channel.

3BHE033067R0103 GCC960C103 solution: I believe that many self-control engineers have encountered similar problems when debugging the system, therefore, I would like to share my own system debugging experience. In the PLC and frequency converter used at the same time in the automatic control system, should focus on the following matters:

1, PLC power supply and power system power supply (inverter power supply) are configured separately, and the PLC power supply should choose the isolation transformer;
2, the power line as far as possible separate from the signal line, the signal line should be shielded;
3, whether analogue signal input or analogue signal output, analogue channel always use signal isolation module;
4, PLC programme to do software filtering design;
5, signal ground and power ground separate design.