PRODUCT INFORMATION
Product Overview
The Allen-Bradley 1791-N4C2 is an Analog I/O Combination Block in the Block I/O 1791 series. This 6-point analog unit operates using a nominal 120 V AC power rating. The hardware integrates four analog input channels alongside two analog current output channels. Voltage inputs provide an input impedance of 10 Megohms and an absolute accuracy of 0.1% at 25 degrees Celsius.
The unit incorporates an internal 24 V DC current-limited voltage source for loop-powered current transducer inputs. Each of the two analog current output channels features an output impedance of less than 1 ohm. These current outputs generate 0 to 20 mA signals with automatic clamping if values exceed the range. The module provides a 10 ms update rate per channel and dissipates up to 16.9 W of power.
TECHNICAL DATA
Technical Specifications
| Parameter | Specification |
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| Category | PLCs |
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| Input Channels | 4 |
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| Number of Channels | 6 |
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| Number of Inputs per Block | 4 Selectable |
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| Output Channels | 2 |
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| Output Impedance | Less than 1 ohm |
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| Outputs per Block | 2 |
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| Power Dissipation | 16.9 Watts Maximum |
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| Product Lifecycle Status* | Discontinued/Obsolete |
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| UPC | 612598122189 |
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| Update rate per channel | 10 ms |
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| Weight | 1.25 lbs (0.57 kg) |
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TECHNICAL INFORMATION
Features
- Provides four configurable analog inputs and two current outputs.
- Operates with a 120 V AC input power rating.
- Delivers an absolute measurement accuracy of 0.1% at 25 degrees Celsius.
- Features an input impedance of 10 Megohms on voltage inputs.
- Provides an output impedance of less than 1 ohm on current channels.
- Integrates an internal 24 V DC current-limited source for loop-powered transducers.
- Achieves a channel update rate of 10 ms.
TECHNICAL INFORMATION
Applications
- Industrial analog process signal acquisition and variable current regulation.
- Distributed field transducer interfacing within legacy Allen-Bradley PLC networks.
TECHNICAL INFORMATION
Connections / Interfaces
- Supports block transfer or discrete transfer communications over Allen-Bradley I/O networks.
- Input channels accept single-ended or differential voltage wiring.
- Analog inputs configure as either all voltage or all current connections.
- Two dedicated terminals supply 0 to 20 mA current output loops.
TECHNICAL INFORMATION
Installation Guidelines
- Wire communication blocks in series along the network line.
- Do not install blocks in a parallel configuration.
- Provide adequate ventilation to dissipate up to 16.9 W during continuous operation.
TECHNICAL INFORMATION
Configuration Guidelines
- Configure the four analog inputs uniformly as all voltage or all current.
- Out-of-range user program write values automatically clamp at maximum or minimum limits.
- Use discrete transfer communications when interfacing with SLC family controllers.
TECHNICAL INFORMATION
Compatibility
- Compatible with Allen-Bradley PLC-2 programmable controllers.
- Compatible with Allen-Bradley PLC-3 programmable controllers.
- Compatible with Allen-Bradley PLC-5/250 programmable controllers.
- Supports discrete transfer communications with Allen-Bradley SLC family controllers.
TECHNICAL INFORMATION
Lifecycle / Replacement Information
- The 1791-N4C2 module is categorized as discontinued and obsolete by the manufacturer.
COMPATIBILITY
Compatibility & Replacement
COMPATIBLE MODELSCompatible with Allen-Bradley PLC-2 programmable controllers. Compatible with Allen-Bradley PLC-3 programmable controllers. Compatible with Allen-Bradley PLC-5/250 programmable controllers. Supports discrete transfer communications with Allen-Bradley SLC family 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
Which controllers communicate with the 1791-N4C2 block?
The module connects to PLC-2, PLC-3, PLC-5/250, and SLC family controllers.
What are the input configuration options on the 1791-N4C2?
The four inputs configure as either all voltage inputs or all current inputs.
Does the 1791-N4C2 module provide transducer power?
It contains an internal 24 V DC current-limited source for loop-powered transducers.
What is the output impedance of the current channels?
The module features an internal output impedance of less than 1 ohm on its current outputs.
