Looking for information on a Harwi Spot Weld Controller. Its a bare bones control board with not much ID except for the firmware version on the ROMs. I have some limited documentation. Looking for the purpose of 2 control line inputs on a 25 pin D-Sub connector. They are marked Control A and Control B from the PLC on the print I have. Can't find anything in Google. I believe it is German. Any help is appreciated.