Configured for high-voltage DC signal monitoring in ControlLogix chassis systems, the Allen-Bradley 1756-IH16I (1756-IH16I Isolated Input Module) provides 16 individually isolated digital input points for 90 to 146 VDC field signals.

Model Identification

The 1756-IH16I is a ControlLogix DC digital input module designed for applications requiring point-to-point electrical isolation between input channels. Each input point operates independently, allowing separate field circuits to be monitored through the ControlLogix I/O architecture.

The module accepts 125 VDC nominal input signals with an operating range of 90 to 146 VDC and transfers input status information through the ControlLogix backplane.

Hardware Specifications

Individually Isolated DC Input Interface

The 1756-IH16I provides 16 individually isolated digital input channels for monitoring independent DC field circuits. Each input point maintains electrical separation from the other channels, reducing interaction between separate input sources.

The module supports sink-source input operation and accepts high-voltage DC signals within the specified 90 to 146 VDC operating range.

Each input channel includes configurable filtering characteristics. The input delay consists of a 6 ms base delay plus the selected filter time.

ControlLogix Backplane and I/O Architecture

The 1756-IH16I communicates with ControlLogix controllers through the chassis backplane. Input states are transferred from the module to the controller for logic execution and system monitoring.

The module belongs to the ControlLogix I/O family, where I/O density scaling depends on chassis capacity, controller configuration, and available power supply resources.

The module does not provide Ethernet/IP communication directly. Network connectivity is handled through separate ControlLogix communication modules installed within the same chassis.

Industrial Control Platform Features

As an Allen-Bradley ControlLogix module, the 1756-IH16I operates within a modular PLC architecture using backplane bus communication between controller, I/O, and communication components.

The module supports isolated channel design for applications where field circuits require independent signal separation. This architecture prevents a fault condition on one input circuit from directly affecting adjacent input channels.

Firmware compatibility and configuration parameters should be matched with the installed Logix controller platform and engineering software version.

Ordering Information

• 1 x Allen-Bradley 1756-IH16I ControlLogix Isolated Input Module
• Catalog number: 1756-IH16I
• Alternate reference: 1756IH16I
• Revision reference: 1756-IH16I/A
• Module function: 16-point individually isolated DC digital input interface
• ControlLogix chassis, power supply, field wiring accessories, and controller hardware are not included unless separately specified.

Installation Guidelines

Chassis Installation

• Install the module into a compatible ControlLogix chassis slot.
• Verify chassis power capacity before installation.
• Apply proper ESD protection during handling.
• Confirm the module is fully inserted into the backplane connector.

Field Signal Wiring

• Connect only DC input circuits within the specified 90 to 146 VDC range.
• Maintain separation between high-voltage DC signal wiring and communication cables.
• Use suitable terminal connections according to the installation design.
• Verify input polarity before energizing field circuits.

Configuration and Commissioning

• Configure input filters according to the required response characteristics.
• Verify each isolated input channel independently during commissioning.
• Confirm controller recognition and I/O status before placing the system into operation.
• Check module diagnostics through the Logix controller environment.

Frequently Asked Questions

• How many input channels are available on the 1756-IH16I?

  The module provides 16 individually isolated digital input points. Each channel operates as a separate isolated input circuit.

• What voltage range does the module accept?

  The input operating range is 90 to 146 VDC, with 125 VDC specified as the nominal input voltage.

• Is each input point electrically isolated?

  Yes. The module provides individual isolation between input points for separate DC field circuit monitoring.

• What type of signals can the 1756-IH16I monitor?

  The module monitors DC digital signals using sink-source input configuration within the specified voltage range.

• What is the input delay time?

  The module has a 6 ms input delay plus the selected filter time configured for the input channel.

• Does the 1756-IH16I provide output switching?

  No. The module is a digital input device and does not contain output switching channels.

• Does the module communicate directly through Ethernet/IP?

  No. Communication occurs through the ControlLogix backplane. Ethernet/IP requires a separate communication interface module.

• Can one input failure affect all channels?

  The individually isolated design separates input points, reducing direct electrical interaction between separate field circuits.