CPU capacity and I/O expansion
The Omron CJ2M-CPU12 is a compact PLC CPU with 64K Words of program memory, expandable up to 40 modules across 3 racks. That memory ceiling handles mid-size machine control sequences without needing a larger frame. Onboard RS-232C and USB ports give direct programming access and serial device connectivity without an extra module. The USB port is the primary link for CX-One software uploads and online edits. Rated for 0°C to 55°C ambient, it sits in a ventilated enclosure without forced cooling in most panel environments. The DIN-rail mount clips onto standard 35 mm rail — no backplate drilling needed.
Approvals include CE, cULus, Lloyd's Register, and NK (Nippon Kaiji Kyokai), covering European, North American, and marine-class installations. The Lloyd and NK marks matter for shipboard or offshore automation where classification society acceptance is mandatory.
Memory and software fit
CX-One software is the programming environment for the CJ2M series. The 64K Words capacity supports ladder, structured text, and function block programming for sequences of 10,000 steps or more. A battery backup preserves the program and retained data during power-down. The battery is a consumable — schedule replacement per Omron's maintenance interval to avoid losing the SRAM contents on a dead cell.