Two digital inputs that you can actually configure
The 3RK1903-0CK00 gives you two digital inputs that are parameterizable — meaning you can set their behaviour (e.g. debounce, inversion) to match the sensor or switch on the line, rather than being stuck with a fixed filter. That's the difference between a module that works in one cabinet design and one that follows the machine revision.
24 V supply with a real operating window
Rated 24 V DC nominal, but the permissible range is 20.4 V to 28.8 V. That 8.4 V window covers a sagging 24 V bus on a long cable run or a slightly overcharged power supply — no separate voltage regulator module needed for this slice. Supply voltage comes in via the backplane bus, so the module draws its control power from the rack — no point-to-point wiring for the 24 V feed. The main energy infeed uses screw-type terminals and the load-side outgoing feeder also lands on screw terminals.
15 mm wide — fits where a wider module won't
At 15 mm wide, this module takes up one slot on the terminal module. Depth is 95 mm, height 196.5 mm. Mounting position is vertical or horizontal — so it works in a shallow enclosure where the DIN rail runs sideways, or a tall cabinet where the rail runs vertically. Fastening method is pluggable on terminal module — the module clips onto a base terminal block, not directly onto the DIN rail. That means you can pre-wire the base, then snap the electronics on after the cabinet is dressed. Saves time on rework if the module needs swapping.
This module supports brake control with 230 V AC — so it can directly switch an AC brake coil on a motor holding brake, without an interposing relay. No brake control for 24 V DC, 180 V DC, or 500 V DC. EMC immunity is to IEC 60947-1, degree of severity 3, ambient A (industrial sector). Surge voltage resistance rated value is 4 kV. That means it's designed for the electrical noise environment of a motor control centre — not just a clean control room.
Lifecycle stage is listed as current. Substance prohibitance date is 05/01/2012 — the module complies with RoHS and REACH requirements as of that date.