Allen Bradley 1791D-16B0 CompactBlock I/O Digital Input Module

Configured for high-density discrete signal acquisition in DeviceNet networks, the Allen Bradley 1791D-16B0 (1791D-16B0 Digital Input Module) provides direct physical/electrical execution of 16 sinking-type input channels. This module interfaces field-side digital sensors with the host controller via the DeviceNet protocol, managing signal state transitions through defined voltage threshold parameters.

Hardware Specifications

DeviceNet Deterministic Network Connectivity

The 1791D-16B0 operates within the DeviceNet architecture, facilitating deterministic data exchange between distributed I/O blocks and the master controller. The module utilizes the network power (11-25 VDC) to drive internal logic and signal sensing circuitry. Integration requires validation of the Electronic Data Sheet (EDS) file within the configuration software to ensure correct mapping of input bits. Firmware flash compatibility should be verified against the DeviceNet scanner module to maintain network timing and prevent packet transmission errors during high-cycle I/O polling.

Frequently Asked Questions (FAQ)

Q: Can this module be used with sourcing-type sensors?

A: No. The 1791D-16B0 is designed specifically for sinking inputs. Attempting to connect sourcing-type field devices will result in a failure to register input logic states correctly.

Q: How is power provided to the input points?

A: The module derives its power for both internal logic and input sensing from the DeviceNet network power supply (11-25 VDC). Ensure the network power supply has sufficient current capacity to support all connected nodes on the segment.

Field Installation Guidelines

• Mounting Stability: Secure the CompactBlock module to a flat, vibration-resistant surface or a DIN rail. Ensure adequate space for cable bend radii to prevent stress on the terminal connections.
• Grounding Requirements: Maintain a common reference ground for the DeviceNet network segment. Use shielded twisted-pair cabling to minimize signal noise, ensuring the shield is grounded at a single, consistent point to prevent ground loops.
• Signal Wiring: Connect field sensors to the input terminals following the sinking input schematic. Ensure that input signals do not exceed the maximum rating of 30 VDC. Segregate low-voltage signal wiring from higher-voltage power cabling to reduce electromagnetic interference (EMI).
• Environment: The module carries an IEC IP20 rating. Install the unit in a clean, dry, and temperature-controlled environment to prevent liquid ingress or dust accumulation which could impede electrical connectivity.