# Omron SYSMAC controllers

> PLCGateway reads and writes Omron NJ/NX, CJ, CS and CP controllers with FINS over Ethernet, or with OPC UA where the controller offers a server.

Omron controllers are connected with FINS over UDP or TCP: DM, CIO, work, holding, auxiliary and EM areas, timers and counters, with BCD and string decoding per tag. NJ and NX controllers with an OPC UA server can also be read symbolically through the OPC UA client.

The data is then logged, alarmed and shown on web screens, used for OEE and energy figures and published to MES and ERP through the OPC UA server.

## Families and models

| Family | Models (examples) | Protocol |
|---|---|---|
| NJ / NX | NJ101, NJ301, NJ501, NX1P2, NX102 — FINS for variables with an AT address; the OPC UA server of models that have one for symbolic access. | [Omron FINS](https://plcgateway.com/protocols/omron-fins.md), [OPC UA client](https://plcgateway.com/protocols/opc-ua.md) |
| CJ2 / CJ1 | CJ2M-CPU3x, CJ2H, CJ1M + CJ1W-ETN21 — Built-in Ethernet (CJ2) or the CJ1W-ETN21 unit. | [Omron FINS](https://plcgateway.com/protocols/omron-fins.md) |
| CS1 | CS1G / CS1H + CS1W-ETN21 — Through the CS1W-ETN21 Ethernet unit. | [Omron FINS](https://plcgateway.com/protocols/omron-fins.md) |
| CP1 | CP1L-EM / EL, CP1H + CP1W-CIF41 — Built-in Ethernet of the E-type CPUs or the CP1W-CIF41 option board. | [Omron FINS](https://plcgateway.com/protocols/omron-fins.md) |

## Notes for commissioning

- FINS/TCP negotiates node numbers automatically; FINS/UDP needs matching node settings.
- On NJ/NX map variables to a memory area with an AT address to read them over FINS.
- Omron stores 32-bit values with the low word first; PLCGateway uses this order by default.
- Mark BCD values per tag.

## Questions and answers

### Can I read NJ variables by name?

Through OPC UA, if the controller has its OPC UA server enabled. With FINS, variables are read through their memory address.

### Is FINS over UDP reliable?

Yes, PLCGateway repeats requests on timeouts and marks values as stale when the controller does not answer.

### Which CP1 models work?

CP1 models with built-in Ethernet (E types) or with the CP1W-CIF41 Ethernet option board.

## Related controllers and devices

- [Mitsubishi Electric MELSEC](https://plcgateway.com/controllers/mitsubishi.md)
- [Siemens SIMATIC](https://plcgateway.com/controllers/siemens.md)
- [Allen-Bradley (Rockwell Automation)](https://plcgateway.com/controllers/allen-bradley.md)
- [All protocols](https://plcgateway.com/protocols.md)

_Product and model names are trademarks of their owners. They are named only to show which equipment the drivers communicate with; PLCGateway is not affiliated with these companies._

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Source: https://plcgateway.com/controllers/omron