1791-N4C2 Allen-Bradley Block I/O 4 Input 2 Output Analog Module

1791-N4C2 Allen-Bradley Block I/O Analog 4-In 2-Out Module

The 1791-N4C2 serves as a robust analog interface for Allen-Bradley distributed I/O systems.
This 6-point block integrates four high-impedance selectable inputs and two precision current outputs into a single compact housing.
Engineers deploy the 1791-N4C2 to handle mixed signal types via discrete or block transfer across Remote I/O networks, ensuring high accuracy in demanding process control environments.

Core Engineering Specifications

• Manufacturer: Allen-Bradley (Rockwell Automation)
• Model Number: 1791-N4C2
• Input Points: 4 Selectable channels (Voltage or Current)
• Output Points: 2 Current channels (0 to 20 mA range)
• Input Impedance: 10 Megohms for high-precision sensing
• Output Impedance: Less than 1 ohm
• Accuracy: 0.1% absolute accuracy at 25°C
• Update Rate: 10 ms per channel for real-time responsiveness
• Power Supply: 120 Volts AC nominal input
• Power Dissipation: 16.9 Watts maximum during full operation
• Internal Source: 24V DC current-limited source for loop-powered transducers

System Compatibility and Logic Integration

• Fully compatible with legacy PLC-2, PLC-3, and PLC-5/250 programmable controllers.
• Supports discrete transfer processes for seamless communication with SLC family controllers.
• Configures independent inputs as either single-ended or differential voltage/current signals.
• Clamps output values automatically at min/max limits if logic data exceeds the 0-20mA range.
• Optimized for series wiring configurations to maintain network integrity across multiple blocks.
• Throughput performance scales directly with the specific controller’s data transfer rates.

Oiltech Controls’s Insight: Application Excellence

• Ideal for wastewater treatment plants requiring remote monitoring of pressure and flow sensors.
• Perfect for retrofitting older PLC-5 systems where panel space prevents adding full I/O racks.
• Replaces complex localized wiring by placing the 1791-N4C2 directly at the machine site.
• Supports loop-powered instruments without needing an extra external 24V DC power supply.
• For immediate technical support, contact info@oiltechcontrols.com or WhatsApp +86 158 8020 0923.

Service, Warranty, and Logistics

• Warranty: Includes a comprehensive 12-month technical functional guarantee.
• Dispatch: Orders ship within 24 to 48 hours following payment verification.
• Shipping Carriers: Global express delivery available via FedEx, UPS, and DHL.
• Condition: Each unit undergoes rigorous testing to meet original OEM performance standards.

Professional FAQ & Selection Guide

• How do I choose between voltage and current modes for the 1791-N4C2 inputs?
  Configuration is handled via internal jumpers or software bit settings depending on your specific controller type.
• What happens if my PLC program sends a value of 22mA to the output?
  The onboard logic will clamp the signal at 20mA to protect downstream actuators from over-current.
• Can I mix voltage and current signals on the four input channels?
  No, you must configure the four independent inputs as all voltage or all current simultaneously.
• Selection Guide: When should I choose the 1791-N4C2 over standard 1771 rack modules?
  Choose this block when you need distributed I/O to reduce expensive long-distance analog cable runs.
• Selection Guide: Does this module support the newer ControlLogix platforms?
  It requires a 1756-DHRIO or similar gateway to communicate with modern Logix processors via Remote I/O.

Author: Oiltech Controls

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