What it is and where it fits
The Omron CS1W-DRM21-V1 is a Communications Module for the CS Series PLC family — sits on the backplane, wired through screw terminals. The approvals list (CE, cULus, Lloyd, NK) covers panel builds bound for general industry, marine, and North American markets.
Still on the production line?
Lifecycle tag reads Active — no end-of-life notice, no last-time-buy scramble. This one's still a standard catalog item. Quote it against your BOM; fast nickel beats slow dime when there's no surplus middleman.