What lands on the backplane
The Omron CJ1W-CRM21 is a CJ-series communications module that drops onto the CJ rack next to the CPU and I/O, carrying up to 2560 positions of messaging across the rectangular connector on its face. It is built for the CJ Series PLC family, the same backplane the CT021 counter or PRT21 Profibus card snap into, so a spare slot in an existing CJ sub-rack is the only panel-side prerequisite. Mounting is DIN-rail, the standard CJ sub-rack anchor, so the module parks in line with the rest of the rack without any adapter plate.
Cabinet-side envelope
Operating envelope is 0 °C to 55 °C, which matches the rest of the CJ1W I/O family and lets it sit in the same cabinet without a separate cooled zone. Field wiring lands on the rectangular connector at the front face, the same termination pattern used across CJ1W specialty modules, so a standard CJ wiring harness is what gets you from the field side to the rack.
Agency marks for cross-border paperwork
Carton markings cover CE, Lloyd, NK, and UL — the set a shipping docket needs to clear EU machinery panels, shipboard consoles, and North American cabinets without a separate compliance file.
Lifecycle and what to expect on the quote
A second internal field flags eol_hot, meaning the part should be treated as a hot running change candidate — confirm a fresh batch date on the carton when the line goes down and pull a spare into the MRO bin before the next reorder window closes.