We occasionally come across the need to share an RS232 port on existing customer equipment. A typical scenario is the need to connect an RTU to our system and to a proprietary SCADA system. We usually solve the problem with a port sharing device such as this one from Black Box. Non-Powered Port-Sharing Device (NPPS) data-sharing devices provide active port contention, draw power from the RS-232 line, are data-transparent in sync or async environments, and support speeds up to 19.2 kbps.