Product Description:

The 7AI351.70 analog input module is built by B & R Automation for the System 2003 Controllers series. Installed on the I/O carrier next to the CPU, it provides one differential channel that can accept either current or voltage feedback from field devices. By digitizing the incoming electrical signal, the board enables the controller to monitor process variables and support closed-loop regulation in factory automation cells.

The signal path uses a 12-bit converter with sign and successive-approximation sampling. For loop-powered transmitters, the terminal accepts a 0 to 20 mA current range, while sensors that generate a voltage can be wired to the differential input pair rated at ±10 V. A high-impedance front end of 20 MΩ minimizes loading on delicate signal sources. Because channel-to-PLC isolation is not provided, the field circuit and backplane share the same reference, which simplifies grounding but must be considered in noisy environments. Protection against wiring faults is provided through short-circuit-tolerant design, and the enclosure has an IP20 rating for finger-safe installation inside a cabinet.

Overall gain deviation does not exceed 0.1% of the final value, and static current offset is limited to ±5 µA, so only minimal scaling correction is typically required in the control program. Nonlinearity remains within 0.05% of span, while voltage offset is capped at ±2.5 mV. A stabilized potentiometer supply delivers ±9.94 V with a maximum draw of 10 mA, allowing external trimming networks up to 0.7 W. The module itself draws only 0.3 W from the backplane, which helps preserve power capacity for other cards in the rack. Short-circuit protection is present on the potentiometer output, and the low power draw helps avoid additional cooling in typical System 2003 installations.