The USB-COMi-PRO is completely jumperless and free of DIP switches, all configuration is done by software. Just press the button and use the configuration program. Serial port on USB allow further use of existing devices, even when the computer doesnt offer serial ports. Now the USB-COMi-PRO is extremely flexible in offered communication standards. Besides the classical RS232 and RS422 it offers six variants of the RS485 operation. The often required Termination and Polarization (BIAS) is also provided by built-in hardware, and it is controlled by the same configuration software. For more details on product, Please refer to http://www.papyrus.co.il/1portusbserialjumperless.htm