Omron NX-AD2208 NX Series 2-Channel Analog Input Module

The Omron NX-AD2208 is a high‑precision analog input module for the NX series of programmable logic controllers and EtherCAT couplers. It provides two isolated analog input channels, each individually configurable for voltage (0–10 V, ±10 V) or current (0‑20 mA, 4‑20 mA) signals. With a resolution of 16 bits (including sign), the module delivers accurate conversion of sensor readings such as pressure, temperature, flow, and level. The NX-AD2208 supports diagnostics including wire break detection and out‑of‑range alarms, and it features a removable screw terminal block for easy wiring. It is designed for use in industrial automation systems requiring high signal integrity and noise immunity.

Technical Specifications

Functional Description

The NX-AD2208 digitizes analog process signals with a 16‑bit analog‑to‑digital converter (ADC). The module performs linearization and scaling within the NX unit, returning the measured value as a signed integer (0–32000) or as a percentage (0–10000). The input range and signal type are set via the Sysmac Studio software. An integrated digital filter (first‑order lag) can be enabled to smooth noisy signals. The module supports input averaging over multiple samples to further reduce noise. The conversion is triggered automatically by the NX bus cycle, and each channel is updated at the configured refresh rate.

Wiring and Connections

The module uses a 10‑position removable screw terminal block (supplied). For voltage input, connect the positive signal to V IN+ and the negative to V IN‑ (or common). For current input, connect the positive to I IN+ and the negative to I IN‑. If the sensor requires an external loop supply, connect the 24V supply appropriately. The module does not provide a sensor excitation output; external power must be used for 2‑wire current loops. Use shielded twisted‑pair cables for all analog signals, with the shield grounded at one end only.

Diagnostic Functions

The NX-AD2208 continuously monitors the input circuit. Wire break detection is available for current inputs (4–20 mA) — if the current falls below 2 mA, an error flag is set. Overrange/underrange detection flags when the measured value exceeds 105% or goes below -5% of the nominal range. These errors can be configured to generate an event (alarm) in the PLC. The module also has a sensor supply error detection that monitors the external 24V supply.

Integration with Sysmac Studio

Configuration of the NX-AD2208 is performed in Omron’s Sysmac Studio software. Users can select the input range for each channel, enable/disable the filter, set the conversion time, and define scaling values. The software also allows the assignment of variable names to each channel. The module is automatically detected when added to the EtherCAT slave configuration or NX bus.

Applications

The NX-AD2208 is used in process monitoring (tank level, temperature), machine control (pressure feedback, flow regulation), and test stands. It is suitable for retrofit and new builds where high‑resolution analog measurement is required.

Conclusion

The Omron NX-AD2208 provides a compact, accurate, and flexible analog input solution for NX series controllers, offering isolated channels, high resolution, and robust diagnostic features for industrial applications.