I know that it is preferable to always shield as close to the electronics component as possible. I have a an HMI screen that I am wiring RS232 and RS485 communications to. I have 2 questions about this:
1) Is it ok to use the same comms cable for both RS232 and RS485. Would a single 22/8 cable work? I know the RS232 can be +/- 14V at extremely low amps, but is this enough to not have it ran in a single cable? Both communications terminate at the same DB-9 at the HMI screen.
2) There is not a good place to ground at the HMI and still keep the ground wire at 2" or less. Is it ok to ground at the on the initial DB-9 and RJ-11 side of the communications, not the HMI side? What is the trade-off here? I do not see how this would affect common mode or differential noise..
1) Is it ok to use the same comms cable for both RS232 and RS485. Would a single 22/8 cable work? I know the RS232 can be +/- 14V at extremely low amps, but is this enough to not have it ran in a single cable? Both communications terminate at the same DB-9 at the HMI screen.
2) There is not a good place to ground at the HMI and still keep the ground wire at 2" or less. Is it ok to ground at the on the initial DB-9 and RJ-11 side of the communications, not the HMI side? What is the trade-off here? I do not see how this would affect common mode or differential noise..