The 39643 makes it easier for you to connect wires from multiple RS-485 sensors into one set of terminals on a data logger. The 39643 uses six DIN-rail mountable (pn 27479), 6-wire terminal blocks. The 39643 is a jumper that electrically connects two terminal blocks together at a time (pn 32918). This setup allows up to 17 RS-485 sensors to be connected to one set of terminals on a data logger.