Allen-Bradley 1791-N4C2: Reliable Analog I/O Module

The Allen-Bradley 1791-N4C2 is a flexible Block I/O module. It adds analog control to your PLC system. This compact module has 4 inputs and 2 outputs. It works perfectly with older Allen-Bradley controllers. The 1791-N4C2 is easy to install and set up. It helps you read sensors and control devices accurately.

Key Benefits & Features

• Versatile Inputs: 4 channels can be set as voltage or current input.
• Stable Outputs: 2 reliable current outputs (0-20mA) for precise control.
• Wide Compatibility: Works with PLC-2, PLC-3, PLC-5/250, and SLC family controllers.
• Easy Power: Includes a 24V DC source for loop-powered sensors.
• High Accuracy: Provides 0.1% accuracy for trustworthy measurements.
• Simple Wiring: Designed for straightforward series connection in panels.

Detailed Technical Specifications

Brand & Model: Allen-Bradley 1791-N4C2
Module Type: Block I/O Analog Module
Total Channels: 6 (4 Inputs, 2 Outputs)
Input Types: 4 Selectable (Voltage or Current)
Input Impedance: 10 MΩ
Output Type: 2 Current Outputs (0-20 mA)
Output Impedance: < 1 Ω
Absolute Accuracy: ±0.1% @ 25°C
Update Rate: 10 ms per channel
Power Supply: 120V AC
Auxiliary Power: 24V DC Sensor Supply (Current-limited)
Max Power Dissipation: 16.9 Watts
Compatible Controllers: PLC-2, PLC-3, PLC-5/250, SLC Family
Communication: Block Transfer or Discrete Transfer
Weight: 1.25 lbs (0.57 kg)

Easy Installation & Use

Mount the module on a DIN rail inside your control panel. Wire the blocks in a series, not parallel. Connect your sensors to the input terminals. Connect your output devices like valve positions to the output terminals. Use the 24V DC source to power loop-powered transmitters. Configure the inputs as voltage or current in your controller program.

Package & Warranty Information

You will receive:
• 1 x Allen-Bradley 1791-N4C2 Analog I/O Module
• Product documentation
(Note: Mounting hardware and cables sold separately)

We provide a full 12-month warranty against defects. Your purchase is protected for reliable performance.

Fast Global Shipping

We deliver worldwide using trusted carriers: FedEx, UPS, and DHL. Tracking information is provided for all orders.

Frequently Asked Questions

Can I use this module with a modern CompactLogix or ControlLogix PLC?

No, this module is designed for older PLC platforms like PLC-5 and SLC 500. For newer ControlLogix, you would need a different series of analog modules.

What types of sensors can I connect to the inputs?

You can connect standard 0-10V or 4-20mA sensors. Examples include temperature transmitters, pressure sensors, or level transducers. Remember to set the input type correctly.

How do I configure the input type (voltage or current)?

The configuration is done through your controller's programming software (like RSLogix 5). You set it in the block transfer setup, not by physical switches on the module.

The output is "clamped." What does this mean?

If your program sends a value outside the 0-20mA range, the output will not exceed its limits. It will stay at 0mA for low values or 20mA for high values, protecting connected devices.

How many of these modules can I use in one system?

The number depends on your controller's I/O capacity and power supply. They must be wired in series on the I/O rack. Check your PLC's manual for the maximum number of block transfer modules allowed.

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