If you are lucky it is RS232, or maybe RS485.<br><br>It could also be a 4ma/20ma current loop, in which case you will need a level translator to connect it to a standard serial port.

There’s still plenty of useful hardware out there that uses an RS-232 interface ... enclosure that [Lasse] has repurposed from a cheap DB15 breakout adapter. The USB cable is used to power ...