"RS232 Jumper Box" https://www.radioparts.com.au/images/ProductImages/30577329.jpg https://www.radioparts.com.au/images/ProductImages/30577329.... I also have

"RS232 Jumper Box" https://www.radioparts.com.au/images/ProductImages/30577329.jpg https://www.radioparts.com.au/images/ProductImages/30577329.... I also have another RS232 device in the attic that shows the signals as LEDs. https://m.media-amazon.com/images/I/41HVXpTp4wL._AC_SL1000_.jpg https://m.media-amazon.com/images/I/41HVXpTp4wL._AC_SL1000_.... Very useful back in the days.