Performance and practicality for machine control

The Omron NX I/O system provides a wide variety of I/O devices. It features an ultra-fast internal bus system that is synchronized with the Distributed Clock of the EtherCAT network. As a result, system-wide deterministic I/O operation allows machine builders to improve machine production rates and output quality.

NX-series I/O covers a full range of units, including standard and high-speed digital I/O's, various performance levels in analogue I/O, encoder inputs and pulse outputs. The series is continuously expanded with e.g. time-stamped I/O, safety I/O, alternative bus systems and application-specific modules.

  • Ideal match with Sysmac Machine automation controllers 
  • Synchronous I/O updates, with less than 1 µs jitter 
  • High density: up to 16 digital or 8 analogue signals in 12 mm width 
  • Removable wiring terminals for easy system assembly and testing

The NX I/O system offers a wide variety of I/O devices. Its ultra-fast internal bus system is synchronized when used with the Distributed Clock of the EtherCAT network. The resulting system-wide deterministic I/O operation allows machine builders to improve machine production rates and output quality.


Omron chose EtherCAT as the control network for the Sysmac NJ Machine Controller series. The convenience of standard Ethernet cabling combined with extremely fast on-the-fly data exchange have resulted in a new machine control architecture. The resulting openness, modularity and determinism are the key elements in today's machine automation.

  • Using open standards for programming and networking assure exchangeability and interoperability with external systems 
  • Modularity allows flexibility in system configurations for fast adaptation to end-user requirements 
  • Determinism is needed to keep control of the machine while increasing performance and accuracy

EtherNet/IP uses the CIP protocol over standard Ethernet infrastructure to offer efficient yet reliable data exchange. Using the EtherNet/IP bus coupler, NX-series I/O - including safety control - can be connected to CJ/CS-series PLC's.


Since each set of NX-series I/O's on an EtherCAT coupler counts as just a single EtherCAT node, the overall network performance is hardly affected by the number of installed I/O units. Keeping the number of EtherCAT nodes to a minimum will help to keep the refresh cycle times of EtherCAT motion axes as low as possible, even at high I/O counts. Furthermore, local fault or damage to an I/O unit will not affect other EtherCAT nodes down the line. The internal bus of the NX-series is fully synchronised with the EtherCAT Distributed Clock. This assures exact timing of any in- or output unit in the control system to within 1 µs, wherever the I/O units are mounted.


For the design of the NX-series, we used our experience in distributed I/O systems combined with customer feedback.

  • The units are compact, with a standard width of 12 mm per unit, yet offer up to 16 channels per unit 
  • The front connectors feature toolless push-in wiring with 8 mm ferrules for wire up to 1.5 mm2 
  • The terminals are removable to allow pre-wiring and safe step-by-step testing 
  • Matching labels on unit and connector reduce the chance of incorrect assembly 
  • You can insert 6 keys in the terminal and the unit to mechanically prevent a mismatch

Digital I/O Units

The NX-series let you mix economical standard I/O's with high-speed synchronous models. The standard digital I/O's have 16 connections per unit, with a choice of:

  • 3-wire sensor connection with power supply (4-channel units) 
  • 2-wire contact inputs or actuator outputs (8-channel-units) 
  • 1-wire connection for sensors and actuators already connected to a common power supply (16-channel units)

High-speed I/O's all use 3-wire connection, and have On/Off response times of less than 300 ns. Using the EtherCAT Distributed Clock, all inputs can be latched, and outputs can be controlled synchronously, with less than 1 µs jitter.For even more control over the exact I/O timing, time-stamp inputs will tell you the exact time of each signal transition. Similarly, time-stamp outputs anywhere in the EtherCAT network can be independently controlled with sub-microsecond accuracy.

Analog I/O Units

Input signals from analogue sensors, 4-20 mA transmitters, thermocouples or resistance thermometers can easily be connected and used for monitoring, data logging, trending or PID control. Analogue units are offered with sampling times down to 10 µs per channel and high resolution (1:30,000). Built-in filtering, offset correction, broken wire- and overrange detection are all standard functions. The user can select from 12 different thermocouple characteristics, °C/°F and indication resolution down to 0.01 degree. With up to eight inputs in just 12 mm width, the NX-series are among the most compact modules on the market today.

Position I/O Units

Various types of encoder signals can be connected, from incremental to Synchronous Serial (SSI) encoders. The ability to synchronize the position data with the EtherCAT Distributed Clock means that the encoder can be used as a motion axis for gearing or following. Pulse outputs up to 500 kHz can be used for discrete control or positioning and can also be mapped as a motion axes when used with the Sysmac NJ machine controller.

Integrated Safety

Safety control units and safe in- and output units can be added to any NX-series EtherCAT I/O stations, to fully integrate safety and standard control in one network. The NX-series fulfills all safety Performance Levels from PL a to PL e. Since the standard NJ-series controllers (V1.06 and up) and NX-series bus couplers (V1.1 and up) can be used, standard control and safety can be scaled independently.