Obsolescence & Migration · 9 min read · Updated November 2026
Omron CJ1, CJ2 and CS1 to NX/NJ: What Changes and What Carries Over
Omron is retiring the CJ-series generation: CJ1G CPUs are already gone in Europe, CJ2M EtherNet/IP CPUs take their last orders in March 2027, and CS1 and NS-series HMIs are winding down. The Sysmac NX/NJ platform is the successor, and it is a bigger change than the Siemens or Mitsubishi migrations — the programming model is different.
Omron's CJ1/CJ2/CS1 controllers run a large share of packaging, electronics and automotive component lines in Asia. The discontinuation schedule published through Omron Europe and Omron Industrial Automation: CJ1G-CPU42P to 45P last order March 2025 (Europe); CJ2M-CPU3x (EtherNet/IP) final order end March 2027, last shipment June 2027; CJ2M-CPU1x (Europe only) final order June 2027. CS1 CPUs and NS-series touch panels are in similar states, with NX/NJ controllers and NA-series HMIs as replacements. Omron normally supports repairs for seven years after discontinuation, but CJ-series spare stock in distribution is already thin for the popular EtherNet/IP models.
Why this migration is different
Siemens S7-300 to S7-1500 or Mitsubishi FX3 to FX5 keep the programming model: same address spaces, same instruction philosophy, converter does most of the work. Omron's Sysmac platform (NX1P2, NX1, NX102, NX7, NJ) replaced the CJ memory-area model (CIO, W, H, D, T, C with word addresses) with fully variable-based IEC 61131-3 programming in Sysmac Studio: structured data types, arrays, function blocks, ST, and EtherCAT as the native I/O and motion network. CX-Programmer projects cannot be converted automatically into Sysmac Studio. Omron does provide a "CX-Programmer to Sysmac Studio" migration guide and a ladder import that preserves rung structure if you export the CJ program as a text file and map addresses to variables, but in practice a CJ2 program is re-engineered, not converted. That is the honest expectation and it changes the economics: migration is a programming project, so you want to do it once, with the right successor, and not before the hardware forces you.
Mapping the platforms
| Legacy | Successor | Notes |
|---|---|---|
| CJ1M / CJ2M (small, built-in pulse outputs) | NX1P2 | Built-in EtherCAT (up to 8 axes), EtherNet/IP, 24 I/O, NX I/O expansion on the right; pulse outputs available as NX-PG modules |
| CJ2H / CJ2M with many racks | NX102 or NX1 series | EtherCAT I/O (NX-ECC) replaces CJ racks; NX102 adds OPC UA and database connection |
| CS1 (large rack, process I/O) | NX7 or NJ5 | For process applications the NX7 with NX I/O; CS1 process modules (CS1W-PTS) have NX-TS equivalents |
| CJ1W-SCU serial units | NX-CIF serial modules or NX1P2 option boards | Modbus RTU, Host Link and no-protocol modes are available but configured differently |
| CJ1W-NC/NCF positioning | EtherCAT servos (1S series) | Motion moves into the CPU with PLCopen function blocks — usually a simplification |
| NS8/NS10/NS12 HMIs | NA5 series | NS projects partially import into Sysmac Studio HMI; screens are rebuilt in the new object model |
What you gain
Done properly, an NX migration removes several weak points of the CJ era: DeviceNet and Controller Link networks are replaced by EtherCAT and EtherNet/IP; the 1S servo (R88D-1SN04H-ECT) with absolute encoder removes homing routines; safety moves from relays (G9SE) to NX-SL safety controllers on the same EtherCAT network when the machine grows; and the whole machine — logic, motion, safety, HMI — lives in one Sysmac Studio project with one tag database. For machine builders this is the point: the next ten machines are cheaper to engineer.
The staged approach we recommend
- Freeze and document. Upload every CJ program with comments, save in CX-Programmer, archive with the HMI project and the DeviceNet/Controller Link configuration. Without comments the re-engineering effort doubles.
- Stock the right spares. CJ2M-CPU31/33/35, CJ1W-PA202/PA205R power supplies, CJ1W-ID211/OD212 I/O, CJ1W-AD081-V1, CJ1W-EIP21 and CJ1W-ETN21 are the units that fail or go short first. Omron does not permit cross-region sales for some SKUs, so verify the model suffix.
- Prototype one machine. Pick the machine with the best documentation, re-engineer it on NX1P2 with NX I/O, run it in parallel on a test bench with simulated I/O, then swap over a weekend. Use it as the template library for the rest.
- Replace HMIs as they fail. NA5 panels talk to CJ2 over EtherNet/IP and to NX, so a new panel can be installed before the CPU migrates.
Cost expectations
For a CJ2M-CPU33 machine with two I/O racks, a positioning unit, two servos and an NS8 panel, a complete NX1P2/1S/NA5 migration is typically 8–12 engineering days plus hardware roughly equal to 70–80 % of the original system in current pricing. The NX1P2 itself is cheaper than the CJ2M it replaces. Where budget is tight, migrate the HMI and the servo axes first — they are the components whose spares vanish first.
Field notes from a CJ2M-to-NX1P2 conversion
A labelling machine with a CJ2M-CPU33, one CJ1W-NC413 positioning unit driving two pulse-input servos, a CJ1W-SCU31-V1 talking Modbus RTU to a barcode printer and an NS8 panel. The sequence that worked: export the CX-Programmer program with comments to a text file and treat the symbol table as the specification; create the NX1P2 project in Sysmac Studio with a global variable for every CIO/W/H/D address actually referenced (about 420 of them — the rest were dead); rewrite the ladder section by section using the same rung order so the old program could be read side by side during testing; replace the NC413 axis logic with MC_MoveAbsolute/MC_MoveRelative function blocks on two 1S servos over EtherCAT, which removed roughly 300 rungs of pulse-count handling; move the Modbus RTU master to the NX1P2's serial option board with the built-in Modbus function blocks; rebuild the eight NS8 screens in the NA5 editor with the new variable names. Elapsed effort: nine engineer-days including two days of parallel testing against the old machine on a simulator and one Saturday for the swap. The machine ran on Monday; the operators noticed the new panel and nothing else, which is the right outcome.
Timing and scan-time differences
CJ2 programs frequently rely on the fixed execution order and the known scan time — for example a one-shot built from a work bit that assumes the scan is longer than a sensor pulse. The NX1P2 runs the primary periodic task at 1–4 ms with a separate task structure, so such constructs can double-trigger or miss. Review every DIFU/DIFD, every self-holding bit that interacts with a timer, and every place where the program reads an input that could change within the scan. Put time-critical I/O in the primary task and everything else in a slower periodic task; it is the opposite of the CJ habit of one big program, and it is where most post-migration oddities come from.
Need engineering help with this?
Our engineers apply this to real projects every week — selection, specification, commissioning. Send your question or a part number.
Quick answers
Can Sysmac Studio import my CX-Programmer project?
Not automatically. Omron provides a migration guide and a ladder import route via text export with address-to-variable mapping, but the CJ memory-area model does not map one-to-one to Sysmac variables. Plan the migration as re-engineering with the old program as the specification.
Will an NA-series HMI work with my existing CJ2 PLC?
Yes. NA5 panels connect to CJ2 CPUs over EtherNet/IP (CJ1W-EIP21 or built-in on CJ2M-CPU3x), which lets you replace ageing NS panels before the CPU migration.
Which Omron CJ parts are hardest to find in 2026?
CJ2M-CPU3x EtherNet/IP CPUs, CJ1W-EIP21 units and the CJ1W-NC positioning modules. We stock tested units and record firmware and lot numbers in every quotation.