B&R X20AT2222 Temperature Input Module

The B&R X20AT2222 is a high-precision temperature input module for the X20 I/O system, designed for resistance temperature measurement using Pt100 and Pt1000 sensors. This module features two input channels with configurable 2-wire or 3-wire connections, making it suitable for a wide range of industrial temperature monitoring applications. With 16-bit resolution and measurement accuracy down to 0.1°C, the X20AT2222 delivers reliable temperature data for HVAC systems, process control, and machine monitoring applications.

Technical Specifications

The X20AT2222 features two analog input channels for Pt100 and Pt1000 resistance temperature detectors. Temperature measurement range: -200°C to +850°C for both Pt100 and Pt1000. Digital converter resolution: 16-bit. Display resolution: 0.1°C. The module supports configurable 2-wire or 3-wire sensor connections. A constant current supply of 250 µA (±1.25%) is used for resistance measurement. Measurement method: Sigma-Delta conversion. Conversion time for 1 channel is 20 ms with 50 Hz filter; for 2 channels, it is 80 ms with 50 Hz filter. The filter time is configurable between 1 ms and 66.7 ms. Input filter type: first-order low-pass filter with cutoff frequency of 500 Hz. Sensor standard: EN 60751. Common-mode rejection at 50 Hz is greater than 80 dB, and at DC greater than 95 dB. Reference resistor: 4530 Ω ±0.1%. Maximum error at 25°C: gain ±0.037%, offset ±0.0015%. Maximum gain drift: ±0.004%/°C. Maximum offset drift: ±0.00015%/°C. Nonlinearity is less than 0.001%. Crosstalk between channels is less than -93 dB. Electrical isolation: 500 V between channel and bus; channels are not isolated from each other. Power consumption from bus: 0.01 W. Internal I/O power consumption: 1.1 W. Operating temperature: -25°C to +60°C (horizontal mounting).

Key Features

• 2 inputs for Pt100 or Pt1000 resistance temperature measurement

• 16-bit digital converter resolution

• Configurable 2-wire or 3-wire sensor connection

• Temperature measurement range: -200°C to +850°C

• Display resolution: 0.1°C

• Configurable filter time (1 ms to 66.7 ms)

• Constant current excitation (250 µA ±1.25%)

• First-order low-pass input filter (cutoff 500 Hz)

• Electrical isolation between channel and bus (500 V)

• Diagnostics: LED status indicators for I/O function, operating state, and module status

• Wire break and range overshoot/undershoot detection

Measurement and Diagnostics

The module uses constant current excitation to measure the RTD resistance. For Pt100 sensors, the 250 µA excitation current generates a voltage drop proportional to temperature, which is amplified and converted to a digital value by the 16-bit Sigma-Delta ADC. The module internally applies the Callendar-Van Dusen equation for Pt100 or linearization for other sensor types. In 3-wire mode, the module compensates for lead wire resistance; in 2-wire mode, external compensation may be required. Diagnostic features include detection of wire break (open circuit), range overshoot/undershoot, and general faults. For temperature measurement monitoring, range undershoot is indicated by 0x8001, range overshoot by 0x7FFF, open circuit by 0x7FFF, and general fault by 0x8000. For resistance measurement monitoring, range overshoot is indicated by 0xFFFF, open circuit by 0xFFFF, and general fault by 0xFFFF. Open inputs are also indicated by 0x7FFF for temperature and 0xFFFF for resistance.

Configuration and Software

Using B&R Automation Studio, engineers can configure each channel individually. Configuration parameters include sensor type (Pt100 or Pt1000), wiring mode (2-wire or 3-wire), filter time, and output format (temperature in °C or °F, or raw resistance). The module outputs temperature in degrees Celsius or resistance value in ohms. Scaling can be applied in the I/O mapping to obtain engineering units. The front panel includes LED indicators for I/O function per channel, operating state, and module status. The B&R ID code for the X20AT2222 is 0x1BA6.

Integration with X20 System

The X20AT2222 connects to the X20 backplane via X2X Link and is compatible with all X20 CPUs and fieldbus couplers (POWERLINK, PROFINET, EtherCAT). It requires a bus module such as X20BM11 and a terminal block (6-pin, X20TB12). The module supports hot-swappable installation within X2X Link networks. The module's compact 12.5 mm width allows high-density mounting, saving control panel space. Up to 64 modules can be connected on a single X2X Link bus.

Applications

Typical applications for the X20AT2222 include HVAC systems (air handling units, chilled water loops), plastic injection molding (barrel and mold temperature monitoring), food processing (oven temperature control), pharmaceutical manufacturing (incubators, freeze dryers), chemical reactors and heat exchangers, packaging machinery (sealing bar temperature), and building automation. The module's 3-wire capability compensates for long sensor cable runs, making it suitable for distributed temperature measurement applications.

Installation and Wiring

The X20AT2222 mounts on a 35 mm DIN rail. The module is designed for X20 6-pin terminal blocks (X20TB12). For 3-wire Pt100 sensors, connect the two lead wires of the same color to the negative terminal and the single wire to the positive terminal. For 2-wire sensors, connect across the appropriate terminals but be aware that lead resistance will add to the measurement. Use shielded twisted-pair cables, with the shield grounded at the controller end. The module compensates for up to 20 Ω of lead resistance in 3-wire mode. When using 2-wire sensors, the resistance of the connecting cable must be measured and compensated externally.

Environmental and Compliance

The X20AT2222 is CE, UKCA, UL, cULus, DNV, CCS, ABS, LR, KR, ATEX Zone 2, and KC certified. Operating temperature: horizontal mounting -25°C to 60°C; vertical mounting -25°C to 50°C. Storage temperature: -40°C to 85°C. Humidity: 5 to 95% non-condensing. Vibration resistance: 5g (10-55 Hz). Protection rating: IP20. The module is designed for pollution degree 2 environments and must be installed in a control cabinet.

Conclusion

The B&R X20AT2222 temperature input module provides high-accuracy, noise-immune Pt100/Pt1000 temperature measurement for industrial applications. With 16-bit resolution, configurable filtering, and 2-/3-wire support, it is a reliable choice for integrating temperature sensing into X20-based control systems.