We have an analog output module 432-1hf00-0ab0 used to control our VFD speed. All of the 0-7 channels were used. 6 out of these channels were frequently giving an output of 0ma channels 0 to 5 and 7, tripping our VFDs. Hardware configuration was set 4-20mA. Initial action was turning cpu stopped then run again turning back the AOs output to initial 4mA.

How can I catch up if the problem was due to my module or some may attributes in it, any diagnostics that I can do?

Thanks in advance for your responses.

Closed cause question posted twice.

The second thread with the subject Analog Output to VFD is published within the conference SIMATIC S7-400 / S7-400H / S7-400F /FH.