What it is and where it lands
The Omron CJ1W-PRT21 is a Communications Module for the CJ Series PLC backplane. It occupies a single slot, mounts on standard DIN Rail, and terminates via a D-Sub connector. The card operates between 0°C and 55°C, which suits most cabinet interiors but not extended temperature zones.
Sourcing and lifecycle reality
This module is a drop-in fit for anyone who already has a CJ1W rack and needs a Profibus–style D-Sub communication card. No adapter or extra hardware is needed beyond the backplane slot.
Integration at the panel
The PRT21 clips onto DIN rail and connects to the CJ backplane via the module's bus connector. D-Sub wiring is straightforward: standard Profibus connectors mate directly. There's no field-adjustable addressing on the module itself; configuration is handled through the PLC program (CX-Programmer or Sysmac Studio).