Nigel,
I think I have the information I need now, but since you asked, I will try to explain my task (and to perhaps simplify my solution a little).
Originally, I posted a question about converting RS-422/485 to RS-232 here:
https://www.electro-tech-online.com/threads/rs-422-485-to-rs-232.29341/
I really did not understand the solution because the voltage specifications between the two standards did make sense to me with the proposed solutions.
Anyhow, I now have a new twist on the specifications that changed the problem. My single board computer has one RS 422/485 port available. I now need to communicate with two different serial (RS-232) devices (one at a time), but only need to transmit data.
My thought was to convert the RS 422/485 output from the SBC to digital logic. Using a couple of AND gates, I can then route the digital signal into the input of one of two RS-232 drivers.
Currently, I am thinking of using the MAX202 or 232, the SN65176, and a 74HC08 AND chip to select between the two RS-232 drivers.
I suspect that a diode and resistor may handle the conversion from the RS-422/485 port to the input of my AND gates but I am still not smart enough to know how to do this. Perhaps you can make a suggestion for this.
Thanks,
Dale