text: <s>[INST] PF400 comms loss problem client has 4 x 250kW PF400 units with 22commD and 22Him3cs door mounted HMI. As soon as I plug the HIMM in, the drive trips on “Comms Loss”. Reset the drive, fault re-appears within a few seconds. Leave HIMM plugged out – no problem then. have flased the 22commD to latest firmware as we had simiular problem with profibus module. this time it is not the solution. Fuzzy lets sea how quick you are on this one [/INST] The HIM is actually powered from the same 5VDC as the 20-Comm-D module and plugging the HIM in has the initial potential to drop the voltage to the point the 20-Comm module loses communication until the HIM fully powers up. Try powering the drive down, install the HIM, and then power the drive back up to see if you again get an error. If you do, you may have a problem with the power regulator for the 5vdc....or a faulty HIM. The HIM should be able to be removed while the drive is in AUTO and not MANUAL mode while the drive is powered up. \\n </s>