I have a DIGI portserver and I want to Connect it To a protection relay with a port db9 RS232, I have an 8 pin connector, how should Be the ALPTIN configuration in the wiring?
“ALTPIN” just means that 8 pins (RJ45) are being used instead of 10 pins (RJ50).
Typically, you would want to either use a “null modem” serial cable or a “straight through” serial cable, depending if the device (in your case, the protection relay) is “DTE” or “DCE”.