The attached files shows analog terminations from flex I/O modules to VFD. I have someone telling me that I should use isolated cards instead of nonisolated cards. I don't see any possibility of noise or ground loops. Why else would I use isolated over nonisolated? Am I missing something? Do you see a problem with the terminations? I am not familiar with flex I/O but it doesn't seem any different than any other analog modules that I have installed. There are also three 4-20mA devices connected to analog input card. The VFD has 0-10V analog output that is connected to a different channel on the same flex I/O input card. I don't see this being a reason to isolate though.
vfdvfd.pdf
