Marshall Electronics CV-USB-RS485 USB to RS485/422 Camera Control Adapter

Marshall's camera control software runs on Windows and talks to the cameras over RS485, which no laptop has. The CV-USB-RS485 bridges the two: a USB type-A plug at one end, a five-position screw terminal block at the other, marked T/R+, T/R-, R+, R- and GND. Plug it into the laptop, land two wires on the terminals, and the control application can drive exposure, white balance, and pan/tilt on any Marshall camera that exposes an RS485 port.

The run between the adapter and the camera is ordinary Cat5 or 24AWG twisted pair, which you supply and cut to length. Wiring is a straight pass: RS485(+) on the camera goes to T/R(+) on the adapter, RS485(-) to T/R(-). Marshall publishes a connection diagram for the adapter, and the same dongle serves the miniature POV heads and the zoom block and PTZ cameras that carry RS485 control terminals.