Allen-Bradley 1794-IB16A Digital Input Module

Allen-Bradley 1794-IB16A is a FLEX I/O digital input module that provides 16 sinking 24 V DC inputs for distributed automation architectures. Designed to mount with a compatible 1794 terminal base (typically 1794-TB3 or 1794-TB3S) and connect to the FLEX backplane, it aggregates 16 field signals into a single remote I/O node suitable for ControlLogix, CompactLogix, and other Rockwell platforms. Each input channel accepts 24 V DC signals with an on-state range of 10–31.2 V and an on-state current up to 12.1 mA, while the off-state leakage remains under 1.5 mA; input impedance is approximately 3.1 kΩ. The module features isolation between the field side and the controller up to 50 V continuous, but there is no isolation between individual channels. Sensor power is provided with a voltage drop of up to 2.2 V, and the sensor power line has short-detect capabilities down to 1.0 A within 10 seconds. Typical Flex I/O power and backplane requirements apply, with a Flex bus current rating around 30 mA at 5 V. This 16-point input module is commonly used to wire 24 V DC sensing devices—such as pushbuttons, limit switches, and proximity sensors—and deliver reliable digital across-plant status to the PLC, enabling scalable, modular expansion of an automation system without sacrificing response time or accuracy.