The X20AT4222 is a special‑function I/O slice for the B&R X20 system, providing four high‑accuracy inputs for resistance temperature detectors (RTDs) such as PT100 and PT1000 according to EN 60751. Each channel can be configured individually for PT100, PT1000 or direct resistance measurement (0.1–4500 Ω or 0.05–2250 Ω depending on gain), allowing the same module to handle temperature probes and generic resistance measurements. Inputs use a constant current source (250 µA ±1.25%) and support 2‑wire or 3‑wire connection per module, with 3‑wire compensation improving accuracy by cancelling lead resistance.
The module uses a 16‑bit sigma‑delta A/D converter with internal linearization, providing a temperature output with 0.1 °C resolution for both PT100 and PT1000 (digital value −2000…8500 representing −200.0…850.0 °C). For resistance measurement, resolution is 0.1 Ω (gain 1) or 0.05 Ω (gain 2), and an internal precision reference resistor of 4530 Ω ±0.1% ensures measurement stability. The filter time is configurable between 1 ms and 66.7 ms, and with a 50 Hz filter the conversion time is 20 ms for 1 channel or 40 ms per channel when 2–4 channels are active.
Electrically, the X20AT4222 provides 500 Veff isolation between channels and the X20 bus, while channels share a common reference (not isolated from each other). It tolerates short‑term input voltages up to ±30 V, has a common‑mode range greater than 0.7 V, and offers very low crosstalk between channels (less than −93 dB), contributing to measurement accuracy. Diagnostics include per‑channel I/O function LEDs, module run/error LED, and software diagnostics for range overflow/underflow and sensor faults.
The module is rated IP20 and can be mounted in horizontal or vertical orientation; in horizontal mounting, the operating temperature range is −25 to 60 °C, and in vertical mounting −25 to 50 °C, with installation altitude up to 2000 m without derating (above 2000 m the ambient temperature must be reduced by 0.5 °C per 100 m). Power consumption is low, at 0.01 W from the bus and 1.1 W internal I/O, and it requires one X20BM11 bus module and one X20TB12 terminal block, ordered separately. Certifications include CE, UKCA, ATEX Zone 2, cCSAus HazLoc, DNV GL, LR, KR, ABS, BV, KC and GOST‑R, making it suitable for hazardous and marine environments.
Typical applications include process temperature monitoring and control for tanks, piping, heat exchangers, ovens and environmental chambers, where accurate multi‑channel PT100/PT1000 measurement is required within an X20‑based control system.
Key Specifications
