1791-NDC Allen-Bradley Analog Block I/O 4 Input 2 Output

Overview

The Allen-Bradley 1791-NDC is a high-precision 24V DC Analog Block I/O module engineered for distributed control systems. It features 4 selectable 14-bit inputs and 2 high-resolution 13-bit current outputs within a single compact housing. Industrial engineers utilize the 1791-NDC for its seamless compatibility with PLC-5 and SLC 5/02 architectures via Universal Remote I/O. Author: Oiltech Controls.

Technical Parameters Overview

• Manufacturer: Allen-Bradley / Rockwell Automation
• Model Number: 1791-NDC
• Product Line: 1791 Block I/O
• Input Count: 4 Selectable Analog Channels
• Input Voltage/Current: ±10V, ±5V, 0-10V, 0-50V, 0-20mA, ±20mA
• Output Count: 2 Current Channels (0 to 20mA)
• Digital Resolution: 14-bit (Inputs) / 13-bit (Outputs)
• Power Supply: 24V DC (19.2 to 30V DC range)
• Current Consumption: 600 mA
• Update Rate: 108 ms per input channel / 10 ms per output
• Accuracy: 0.1% Absolute accuracy at 25 degrees Celsius
• Bandwidth: 5 Hz Input Bandwidth

Oiltech Controls’ Insight & Application

• Target Systems: This module provides essential analog expansion for PLC-2, PLC-3, and PLC-5/250 series controllers.
• Transducer Support: The 1791-NDC includes an internal current-limited voltage source for loop-powered transducers.
• Signal Integrity: High input impedance (10 MΩ for voltage) ensures minimal signal loading and higher precision.
• Noise Rejection: Features -75 dB Common-mode rejection to handle electrically noisy industrial environments.
• Circuit Protection: Engineers benefit from indefinite short circuit protection and 140V AC overvoltage ratings.

Installation & Thermal Management

• Mounting Dimensions: 6.95 x 2.7 x 3.85 inches (Compact Remote I/O footprint)
• Thermal Load: 39.28 BTU/hr maximum dissipation requiring proper ventilation clearance.
• Power Dissipation: 11.52 Watts maximum at full load.
• Data Transfer: Supports both Block Transfer and Discrete Transfer protocols.
• Weight: 1.00 lbs (0.45 kg) per unit.

Ordering & Shipping Standards

• Dispatch Time: Guaranteed shipping within 24-28 hours from order confirmation.
• Global Logistics: Express delivery via Fedex, UPS, and DHL.
• Quality Assurance: Includes a standard 12-month hardware warranty.
• Price Inquiry: Contact info@oiltechcontrols.com for official quotations.
• Live Support: Chat with us on WhatsApp: +86 158 8020 0923.

Expert Selection Guide & FAQ

• Question: Which input range should I select for 4-20mA pressure transmitters?
• Answer: Configure the 1791-NDC for 0-20mA mode; the 14-bit resolution provides ample headroom for the 4-20mA live-zero signal.
• Question: Can I mix voltage and current signals on the same block?
• Answer: Yes, you can configure the 4 input channels independently to match various field instrument types.
• Question: What is the benefit of the 5 Hz input bandwidth?
• Answer: This low-pass filtering effectively eliminates high-frequency industrial noise from the analog signal path.
• Question: How do I manage accuracy drift in high-temperature panels?
• Answer: Selection Guide: Since the drift is 75 ppm/°C, ensure the panel temperature remains near 25°C for maximum 0.1% accuracy.
• Question: Does this module require a separate power supply for the RIO link?
• Answer: No, the 1791-NDC draws communication logic power from the internal 24V DC supply, simplifying wiring.

Copyright © 2026 Oiltech Controls Limited. https://www.oiltechcontrols.com/ All rights reserved.
All rights reserved.