Memory budget and scan cycle constraints
The CJ1M-CPU13 allocates 20K program steps and 32K words of data memory — the data area is the tighter constraint for applications with large recipe tables or array-based sequencing. With the 32K-word ceiling, expect to budget roughly 8–10K words for I/O mapping and system flags before the application logic starts, leaving about 22K words for user data.
I/O expansion ceiling for system sizing
One rack supports up to 20 modules — that is the physical limit before a second CPU rack or a CJ1W-IC101 inter-rack connection is needed. The RS-232C port handles programming downloads and peripheral connections (operator interface or serial barcode reader), but it is not a fieldbus master — an expansion module is required for DeviceNet, Profibus, or EtherNet/IP.
DIN-rail mounting per EN 50022 — the unit snaps onto the standard 35 mm rail and occupies one CPU slot width in the CJ1 backplane. No display on the CPU — status is read from the RUN/ERR/COMM LEDs on the front bezel.
Lifecycle and sourcing — obsolete, not a dead end
Omron lists the CJ1M-CPU13 as obsolete — no official successor part number is published for this exact CPU variant. No stock-holding claim — quantities are lot-specific.