OEMAX NX-RTD8 8-Channel RTD Input Module

The OEMAX NX-RTD8 is a high-precision temperature input module designed for the NX Series PLC system. It provides eight independent channels for connecting resistance temperature detectors (RTDs), specifically Pt100 and Ni100 sensors. The module is ideal for industrial applications requiring accurate temperature measurement, such as HVAC control, plastic injection molding, food processing, and chemical reactors. It supports 3-wire and 4-wire connection methods to compensate for lead resistance errors.

High-Accuracy Temperature Acquisition

The NX-RTD8 uses a 16-bit analog-to-digital converter to achieve 0.1°C resolution, ensuring precise temperature monitoring for critical processes. The module automatically compensates for lead wire resistance when using 3-wire or 4-wire RTDs, eliminating errors caused by long cable runs. Each channel is independently configurable for sensor type and connection method. The built-in constant current excitation source (1 mA) is optimized for Pt100 and Ni100 sensors to minimize self-heating effects.

Diagnostics and Safety

Each channel features sensor break detection: if the RTD circuit is open or shorted, the module reports an error to the PLC, and the corresponding front‑panel LED flashes. This allows rapid identification of faulty sensors. The module also includes input filtering to reject 50/60 Hz noise. Galvanic isolation between channels and the backplane protects the PLC from ground loops and voltage transients.

Application Domains

The NX-RTD8 is used in HVAC systems (air handling units, chiller temperature monitoring), plastic injection molding (barrel and nozzle temperature control), food and beverage processing (ovens, pasteurizers, refrigerators), chemical reactors and batch processes, pharmaceutical manufacturing (incubators, stability chambers), and environmental monitoring in greenhouses or cleanrooms.