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The USB488RJ-ISO is an isolated version of the popular DMX Open dongle.


  • USB "B" type connector
  • Two RJ45 connectors (in parallel) for DMX (ESTA pinout)
  • Power, transmit and receive LEDs
  • DMX I/O is electrically isolated from USB
  • Supplied in a small plastic case that can be screwed down
  • USB chip is an FT232RL (uses a common driver)
  • Software compatible with LOR (need an adapter cable)

USB Input

The PC connection to the USB485RJ-ISO is via a standard USB "B" connector. The unit is powered from the USB input.

RS485 Outputs

There are two RJ45 connectors for RS485 or DMX I/O. They are wired in parallel. The RJ45 pinout is per the ESTA standard with the addition of pins 4+5 being connected together to allow use in P-DMX systems.


The termination ("TERM") jumper is located internally, next to one of the RJ45 sockets. Leave this jumper on if the interface is the last item in the wiring chain (only one socket used). Remove it if the interface is in the middle of the wiring chain (both sockets used).


There are 3 small LEDs on the top of the enclosure.

The power LED will be on steady whenever power (via USB) is applied to the USB485RJ-ISO.

The Tx (transmit) and Rx (receive) LEDs flash briefly upon initial connection and during normal operation.


The RJ45 (RS485 / DMX) side is electrically isolated from the USB (PC) side. The eliminates ground loops between the PC and connected equipment. It will also provide protection to your PC in the event of excessive voltages appearing on the RJ45 side. Please note that excessive voltages may still damage the USB485RJ-ISO, but the PC should escape unscathed.


The USB485RJ-ISO requires a driver to be installed on the PC. A lot of the time, your PC will already have this driver present.