PRODUCT INFORMATION
Product Overview
The Allen-Bradley 1791D-4B4P is a CompactLogix Base Module - 4 Inputs/4 Outputs designed for distributed DC block I/O operations. This unit features four sinking inputs and four sourcing outputs in a compact IEC IP20 enclosure. Operating on DeviceNet power between 11 and 30V DC, it delivers deterministic communication across networked industrial automation systems. The hardware integrates a built-in watchdog function that continuously tracks microprocessor execution to detect system faults.
The sinking digital inputs conform to NEMA type 1+ specifications and accept a broad selection of industrial sensors. Input voltage ratings support 30V DC at 40 degrees Celsius and 25V DC at 60 degrees Celsius. Engineers can configure selectable input filters to set specific on-to-off and off-to-on signal delay times. The sourcing outputs provide a continuous voltage range of 10 to 30V DC for field devices. Data exchange with the network master occurs using change-of-state, cyclic, or polled messaging formats.
TECHNICAL DATA
Technical Specifications
| Parameter | Specification |
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| Category | PLCs |
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| DeviceNet Power | 11-30V dc |
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| Enclosure | IEC IP20 |
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| Input Off-state Current | 1.5mA @ 5V dc min. |
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| Input Off-state Voltage | 5V dc max. |
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| Input On-state Current | 11mA @ 30V dc max. |
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| Input On-state Voltage | 10V dc min. |
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| Input Type | Sinking |
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| Inputs per Block | 4 |
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| Output On-state Current | 0.5 A max. |
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| Output On-state Voltage Range | 10-30V dc |
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| Output Type | Sourcing |
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| Outputs per Block | 4 |
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| Weight | 0.44 lbs (0.20 kg) |
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TECHNICAL INFORMATION
Features
- Provides four sinking DC inputs and four sourcing DC outputs per block.
- Supports DeviceNet bus power operating within an 11 to 30V DC range.
- Equipped with an IEC IP20 rated housing suitable for industrial control enclosures.
- Incorporates NEMA type 1+ input circuitry for broad sensor interface capability.
- Includes configurable input filter delays for both on-to-off and off-to-on transitions.
- Features an internal hardware watchdog to monitor microprocessor health status.
- Enables flexible communication modes including polled, cyclic, and change-of-state messaging.
- Supports I/O expansion configurations such as 20 input/4 output or 4 input/20 output schemes.
TECHNICAL INFORMATION
Applications
- Distributed digital signal monitoring in DeviceNet field networks.
- Interface connectivity for 24V DC industrial sensors and proximity switches.
- Control of discrete field actuators requiring 10 to 30V DC sourcing power.
TECHNICAL INFORMATION
Connections / Interfaces
- Connects to 11-30V DC network bus power via dedicated DeviceNet terminal interfaces.
- Features four discrete sinking input terminals compatible with standard 24V DC field sensors.
- Provides four sourcing output terminals supplying 10 to 30V DC to external actuators.
TECHNICAL INFORMATION
Installation Guidelines
- Mount the module within an appropriate control cabinet meeting IEC IP20 environmental protection requirements.
- Maintain adequate ventilation spacing around the housing to respect ambient operating temperature limits.
- Ensure input field voltage levels conform to thermal operational derating thresholds.
TECHNICAL INFORMATION
Configuration Guidelines
- Select between polled, cyclic, or change-of-state messaging to optimize network bandwidth.
- Adjust digital input filter delay times to match sensor switching speeds and suppress noise.
- Allocate one byte consumed and one byte produced for base four-input, four-output configurations.
- Expand the addressing structure when adding expansion modules up to 20 inputs or 20 outputs.
TECHNICAL INFORMATION
Compatibility
- Integrates into Allen-Bradley DeviceNet communication networks and CompactLogix controller architectures.
- Interfaces directly with standard sinking 24V DC digital input sensors.
- Compatible with expansion I/O blocks under supported 20-in/4-out and 4-in/20-out topologies.
COMPATIBILITY
Compatibility & Replacement
COMPATIBLE MODELSIntegrates into Allen-Bradley DeviceNet communication networks and CompactLogix controller architectures. Interfaces directly with standard sinking 24V DC digital input sensors. Compatible with expansion I/O blocks under supported 20-in/4-out and 4-in/20-out topologies.
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 1791D-4B4P?
The 1791D-4B4P is a distributed I/O block that provides four DC inputs and four DC outputs on DeviceNet.
How does ambient temperature affect the input characteristics of the 1791D-4B4P?
The module accepts 30V DC on-state voltage at 40 degrees Celsius and 25V DC at 60 degrees Celsius.
What communication modes are supported by the 1791D-4B4P module?
The unit supports polled, cyclic, and change-of-state data exchange with the master controller.
What expansion options are available for the 1791D-4B4P base block?
The module supports expansion configurations of 20 inputs with 4 outputs or 4 inputs with 20 outputs.
