RS-232 and RS-422 are legacy interfaces. Tau2 and Quark2 cameras still have some vestigial support, as follows. RS-232 transceivers invert the polarity of the signals, so the sense or polarity of the local logic signal is the opposite of the polarity of the transmission wire signal. Tau2 and Quark2 cameras recognize the difference, so this is transparent to a design. An RS-232 signal could be connected directly to the Tau2 for short runs, or a transceiver and surge protection could be used to provide longer cable drive and reliability, and the Tau2 or Quark2 would operate the same in either case. Unfortunately, for RS-422 a transceiver would always be needed.