I have an old Panelview 800 in a system that consists of the PV, a Micro 850 and 10 Powerflex VFd's running conveyor motors.
My problems started when one of the motors would not run. It seemed that the PLC was not sending the Run command or the Speed. The problem got worse as I was working on it when two others did the same thing. The current situation is that 8 of the VFD's are getting a Run command and 2 are getting a flickering command. All 10 are getting a 0.0Hz speed command.
I connected to the equipment with my laptop and looked at the PLC program and the PV program. I found that in the PV program that all of the user input data, which consists of Motor Speed (Hz), Accel and Decel times and some other timer values for the timing of some conveyor starts and stops, where all gone, set at '0'. this equipment is several years old and predates my presence here. The PLC program seems to be running and passing the commands that it receives to the VFD's. The data is passed to the PLC via Global Variables.
I've never encountered this particular problem before. Any ideas?