Do I need a USB Isolator when controller motors via a PC?

[eeguy]

Hi, I plan to use a PC to control some motors. The total amp under full load is about 60-80Amp, 12V. I have two devices (usb to rs485 interface adapter and a controller board with usb connection to the PC and several rs485 connectors to connect to the motors). Do I need to worry about the motors damaging the USB port of the PC? If so, what USB Isolator do you recommend? Thanks

[Mp3]

Will one of the ADUM3160 / ADUM4160 premade adapters work for you? They're readily available from many places around $10. I was about to DIY one out of some parts from Mouser but these come in lower on the $ count and are premade.

[wizard69]

Well it depends.   A good isolator should protect you from mistakes and transients.  The bigger question in my mind is why are RS 485 line going to the motors?   It almost sounds like you have motors with integrated controllers /drives but you state that the controller is separate. 

I’d almost certainly look at every device connected to to see if their ports offer isolation. You may not need isolation if it is already incorporated into the motor controls.  There are lots of other factors to consider so it isn’t that simple.   For example does your control cabinet have high voltage devices, RF sources, large inductive noise producers such as relays.  In an industrial solution there are often these risks to your equipment so isolated ports are often the default. 

[eeguy]

Will one of the ADUM3160 / ADUM4160 premade adapters work for you? They're readily available from many places around $10. I was about to DIY one out of some parts from Mouser but these come in lower on the $ count and are premade.

Do you know which is good? There are lots of them. Some look the same or almost the same but from companies I have never heard of. There are $10-30 up to $250.