The Mcom101s is a bi-directional USB-powered RS485
to USB converter with built-in 120 ohm termination option, which makes a
half-duplex RS485 available to a PC via the USB port. The USB-485B has a db-9
male connector on the RS485 port, and a USB type A female on the USB port. The
adapter is powered from the USB port and no external power is needed. USB
cable, terminal block, and drivers are included in the package. This
converter operates from 300 to 1 mbps.
Interfacing Field instrumentation with SCADA / PLC/