PRODUCT INFORMATION
Product Overview
The Allen-Bradley 1791-NDC is a 24V DC analog I/O module in the Block I/O 1791 series. It provides four configurable analog inputs and two current outputs on a single base unit. The device operates from an input voltage range of 19.2 to 30V DC. It draws a nominal operating current of 600 mA during standard operation. An integrated current-limited source supplies 24V DC for loop-powered current transducers.
This module communicates with host programmable controllers through block transfer or discrete transfer modes. Input channels feature an update rate of 108 milliseconds and a 5 Hz bandwidth. The two current outputs provide an internal update rate of 10 milliseconds. Output resolution is 13 bits across an operating span of 0 to 20 mA. Indefinite short-circuit protection safeguards the output circuitry during electrical faults.
TECHNICAL DATA
Technical Specifications
| Parameter | Specification |
|---|
| UPC | 662468177757 |
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| Weight | 4.19 lbs (1.90 kg) |
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| Inputs | 4 |
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| Input Type | Analog |
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| Outputs | 2 |
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| Output Type | Current |
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| Power Suppply Voltage | 24V DC |
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| Update Rate per Channel | 108 ms |
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| Power Dissipation | 11.52 W max. |
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| Thermal Dissipation | 39.28 BTU/hr. max. |
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| Current | 600 mA |
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| Input Bandwidth | 5 Hz |
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| Product Lifecycle Status* | Discontinued/Obsolete |
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TECHNICAL INFORMATION
Features
- Four analog input channels supporting voltage and current signal selections.
- Two analog current output channels with 13-bit conversion resolution.
- Built-in 24V DC current-limited voltage source for field transmitter loops.
- Indefinite short-circuit protection on all analog current output channels.
- Overvoltage protection rated up to 140V AC on inputs and outputs.
- Selectable communication modes using block transfer or discrete transfer.
TECHNICAL INFORMATION
Applications
- Analog field instrumentation monitoring in legacy PLC-5 and SLC 500 automation architectures.
- Direct interface to 4-20 mA and 0-20 mA loop-powered process transmitters.
- Distributed machine control requiring local analog current loop actuation.
TECHNICAL INFORMATION
Connections / Interfaces
- Four configurable analog input terminals supporting voltage or current wiring.
- Two analog current output terminals with continuous short-circuit protection.
- Field wiring points for an external 19.2 to 30V DC operational power supply.
TECHNICAL INFORMATION
Installation Guidelines
- Verify the incoming power supply remains within 19.2 to 30V DC before energizing.
- Maintain adequate ventilation around the block to dissipate up to 39.28 BTU per hour.
- Ensure signal wiring routes separately from high-voltage motor circuits to reduce electrical noise.
TECHNICAL INFORMATION
Configuration Guidelines
- Select input ranges using configuration bits according to transducer specifications.
- Configure controller communication logic for either block transfer or discrete transfer operation.
TECHNICAL INFORMATION
Compatibility
- Allen-Bradley PLC-2 programmable controllers.
- Allen-Bradley PLC-3 programmable controllers.
- Allen-Bradley PLC-5 and PLC-5/250 programmable controllers.
- Allen-Bradley SLC 5/02 modular controllers.
TECHNICAL INFORMATION
Lifecycle / Replacement Information
- The 1791-NDC module carries obsolete and discontinued product lifecycle status from the manufacturer.
- Units remain available through specialized surplus, remanufactured, and active maintenance inventory channels.
TECHNICAL RESOURCES
Documentation
COMPATIBILITY
Compatibility & Replacement
COMPATIBLE MODELSAllen-Bradley PLC-2 programmable controllers. Allen-Bradley PLC-3 programmable controllers. Allen-Bradley PLC-5 and PLC-5/250 programmable controllers. Allen-Bradley SLC 5/02 modular controllers.
Verify compatibility against the exact Part Number, revision and manufacturer documentation before ordering.
PART VERIFICATION
Before You Order
Industrial automation parts can share similar model names, suffixes and revisions. Confirm the complete manufacturer Part Number before purchase.
01Check Part NumberMatch the complete ordering code on the existing unit.
02Confirm RevisionCheck suffix, hardware or firmware when applicable.
03Send a Label PhotoWe can review a clear label photo when identification is uncertain.
ORDERING PROCESS
From RFQ to Dispatch
1Submit Part Number2Verify Product Identity3Confirm Stock & Condition4Issue Quotation5Dispatch & Tracking
PRODUCT FAQ
Frequently Asked Questions
What is the primary function of the Allen-Bradley 1791-NDC?
It provides four analog inputs and two analog current outputs for PLC-2, PLC-5, and SLC 5/02 systems.
What are the input and output channel ratings on the 1791-NDC?
Inputs offer 14-bit resolution with 108 ms update rates. Outputs provide 13-bit resolution across 0 to 20 mA.
What is the market reference price for the 1791-NDC?
Observed market reference pricing spans $1,390.00 to $6,870.23 USD. These figures are indicative market reference pricing only and are not a final quotation.
