Quote Originally Posted by Doddy View Post
Just to discount this - this is part of the serial protocol used to communicate with the VFD and is used for the framing of the individual packets of data. Not to be confused with the VFD operation.

Basically, it helps the comms between the computer and the VFD, nothing else.
Ok.
So it's the normal I/O outputs to relays / contactors and estop circuits doing the work then.
Good to know.