Schneider BMXART0814 8-Channel Isolated Thermocouple Input Module

The Schneider BMXART0814 is an analog input module for the Modicon M340 automation platform, providing eight isolated channels for thermocouple temperature measurement. Each channel is galvanically isolated from the backplane and from each other, ensuring high noise immunity. It supports eight standard thermocouple types: J, K, T, S, R, B, E, and N.

Input Ranges and Accuracy

Measurement ranges vary by thermocouple type, typically from -270°C to +1820°C (type B max). Resolution is 15 bits plus sign. Accuracy is ±0.1% of full scale at 25°C ambient, with cold junction compensation error less than ±1°C. The module performs linearization and scaling directly to engineering units ( °C, °F or K).

Cold Junction Compensation

Cold junction compensation (CJC) is achieved via an internal sensor located on the removable terminal block. An external CJC sensor can also be connected for improved accuracy when the terminal block is remote. The module automatically applies correction, eliminating manual offset calculations.

Filtering and Sample Rate

Each channel has a programmable digital filter (50 Hz or 60 Hz rejection) to suppress power-line noise. Update time per channel is 80 ms with filter enabled, 40 ms without filter. Users can configure channels for different thermocouple types and sample rates independently.

Diagnostics and Safety

The module detects open-circuit, short-circuit, and over-range conditions. Broken wire detection triggers a configurable alarm. LEDs indicate module status, field power, and channel errors. It complies with IEC 61131-2 for industrial environments.

Installation and Wiring

Wiring uses a 20-pin removable screw terminal block (included). Shielded thermocouple extension wires are recommended. The module draws 100 mA from the 5V backplane and requires no external 24V supply. Dimensions are standard M340 format: 32 x 100 x 86 mm.

Configuration with Unity Pro

Using Schneider's Unity Pro software, users assign each channel a thermocouple type, engineering unit, and filter setting. Real-time values are stored in internal memory words. The module supports scaling to custom ranges if needed.

Applications

Ideal for heat treatment furnaces, injection molding machines, kilns, HVAC monitoring, and laboratory ovens. The eight isolated channels allow measurement of distributed temperature points without grounding loops.

Conclusion

The Schneider BMXART0814 provides highly accurate, isolated thermocouple measurement for Modicon M340 systems. Its support for multiple thermocouple types and built-in diagnostics make it a robust choice for temperature-critical processes.