Product Description:

The 7AT324.70 module is an analog resistance measurement card manufactured by B&R Automation as part of the System 2003 Controllers series. Installed on a System 2003 backplane, it acquires temperature or process data from resistive sensors and delivers digitized values to the CPU for closed-loop tasks in industrial automation. By providing four isolated input channels, the card enables a controller to monitor multiple heat zones, machine bearings, or environmental probes without external signal conditioners. This arrangement helps reduce wiring complexity in distributed I/O cabinets.

Each channel uses a 16-bit analog-to-digital converter, so the quantization step is small enough for fine thermal control. Under reference conditions, the module holds a basic error of ±0.1 % at 25 °C, keeping the converted value closely aligned with sensor resistance. The front end rejects unwanted voltages, and its common-mode suppression is rated at greater than 90 dB DC and greater than 150 dB at 50 Hz, which helps shield the measurement from ground shifts and mains hum. A 60 ms per channel standard sample time balances update rate and noise, while an extended 190 ms setting is available when higher accuracy is needed. Conversion relies on a Sigma-Delta topology paired with a 150 Hz first-order low-pass filter, a combination that attenuates high-frequency components before digital processing. The card accepts signals through a 2-wire resistance method and maintains synchronization across its four inputs.

During a reading, the module sources a constant excitation of 200 µA ±5.22 % through the connected element, limiting self-heating while keeping signal amplitude predictable. Two gain ranges are selectable. The wider span handles resistances from 1–4995 Ω, allowing direct connection of KTY10-6, KTY84-130, PT100, and PT1000 sensors across their full operating temperature ranges of −50 to 150 °C, −40 to 300 °C, and −200 to 850 °C respectively. Typical internal dissipation is only 0.1 W, and the front housing meets the IP20 ingress rating for installation inside a protected control cabinet.