Product Overview

The Allen Bradley 1790-8BV8BX CompactBlock LDX I/O Expansion Block is a combination digital input and output module developed for distributed industrial automation applications. Its 16-point configuration integrates eight universal digital inputs with eight sourcing digital outputs, providing a practical solution for systems requiring both signal monitoring and field-device control.

The input channels support sinking and sourcing configurations, with a nominal operating voltage of 24 V DC. The output channels use a sourcing design and support up to 0.5 A per output, with a maximum of 4.0 A per common. This configuration allows the module to connect compatible sensors, switches, and DC-controlled devices within the same I/O assembly.

For maintenance and troubleshooting, the module provides green channel-status indicators. Photocoupler isolation between the I/O and logic circuits helps separate field-side electrical signals from internal control electronics. Its 37-pin D-shell connector provides an organized interface for field wiring.

As part of the CompactBlock LDX product family, the 1790-8BV8BX is intended for compatible DeviceNet installations. It is suitable for machine automation, distributed control, and maintenance of existing industrial I/O systems.

Rockwell Automation discontinued this model effective September 30, 2023. It remains relevant to legacy equipment support and spare-parts procurement where the original mixed-I/O configuration must be maintained.

Technical Specifications

Parameter	Specification
Brand	Allen Bradley
Model	1790-8BV8BX
Product Series	CompactBlock LDX
Product Type	Digital I/O Expansion Block
Communication Network	DeviceNet
Total I/O Points	16
Digital Inputs	8 Universal Inputs
Input Configuration	Sinking or Sourcing
Input On-State Voltage	9.6–28.8 V DC
Nominal Input Voltage	24 V DC
Maximum Input Current	8 mA per point at 28.8 V DC
Input Off-State Voltage	5 V DC Maximum
Input Impedance	4.8 kΩ
Digital Outputs	8 Sourcing Outputs
Output On-State Voltage	10–28.8 V DC
Maximum Output Current	0.5 A per channel
Maximum Current per Common	4.0 A
Maximum Output Voltage Drop	0.5 V DC
Maximum Off-State Leakage	0.5 mA
Output Signal Delay	0.5 ms OFF-to-ON / 1.0 ms ON-to-OFF
Status Indicators	Green Input and Output LEDs
Isolation	Photocoupler, I/O to Logic
Isolation Voltage	1250 V AC RMS
Connector	37-Pin D-Shell
Protection Rating	IP20
Dimensions	104 × 42 × 52 mm
Weight	0.1 kg / 0.22 lb
Lifecycle Status	Discontinued

Recommended Related Models

The following Allen Bradley models are relevant to CompactBlock LDX digital I/O expansion projects:

1790-8BV8VX – CompactBlock LDX 8-Point Universal Input and 8-Point Sinking Output Expansion Block.
1790-16BV0X – CompactBlock LDX 16-Point Universal Input Expansion Block.
1790-0B16X – CompactBlock LDX 16-Point Sourcing Output Expansion Block.
1790-0V16X – CompactBlock LDX 16-Point Sinking Output Expansion Block.
1790-0W8X – CompactBlock LDX 8-Point Relay Output Expansion Block.

These models provide different I/O configurations. Selection should be based on the required input type, output switching method, and existing system architecture.

Popular Related Models

1790-T8BV8BX – Allen Bradley CompactBlock LDX 8 Universal Input / 8 Sourcing Output Expansion Block with Screw-Clamp Connection.
1790-T8BV8VX – Allen Bradley CompactBlock LDX 8 Universal Input / 8 Sinking Output Expansion Block with Screw-Clamp Connection.
1790-T16BV0X – Allen Bradley CompactBlock LDX 16-Point Universal Input Expansion Block.
1790-T0B16X – Allen Bradley CompactBlock LDX 16-Point Sourcing Output Expansion Block.
1790-T0V16X – Allen Bradley CompactBlock LDX 16-Point Sinking Output Expansion Block.

When purchasing the 1790-8BV8BX, confirm the complete catalog number, input and output configurations, connector type, and compatibility with the installed DeviceNet system. Since this model is discontinued, verify stock condition and hardware authenticity before ordering.

Applications

The Allen Bradley 1790-8BV8BX CompactBlock LDX I/O Expansion Block is a 16-point combination digital I/O module designed for DeviceNet-based industrial automation systems. It integrates eight universal digital inputs and eight sourcing digital outputs in one compact expansion block.

This combination allows automation systems to collect field signals and control external devices through a single module, making it suitable for applications such as:

Manufacturing Automation: Monitors machine signals and controls compatible DC field devices on production lines.
Conveyor Systems: Collects sensor signals and controls auxiliary equipment through digital outputs.
Packaging Machinery: Supports discrete signal acquisition and actuator control.
Industrial Equipment Monitoring: Receives signals from proximity switches, limit switches, and other field devices.
Process Automation: Provides distributed digital input and output functions in compatible control architectures.
DeviceNet Installations: Expands the I/O capacity of existing CompactBlock LDX systems.

Key Features and Advantages

1. Combined Digital I/O Configuration

The module integrates eight universal inputs and eight sourcing outputs, providing both signal acquisition and device control in one expansion block.

2. Universal Input Flexibility

The eight input channels support sinking and sourcing configurations. This flexibility simplifies integration with different types of compatible field sensors and switches.

3. 24 V DC Sourcing Outputs

The eight output channels use a sourcing configuration and support a maximum output current of 0.5 A per channel, subject to the common current limit.

4. Individual Channel Indicators

Green LED indicators provide visual status information for the input and output channels, helping technicians identify signal conditions during troubleshooting.

5. Photocoupler Isolation

The I/O circuits use photocoupler isolation from the logic circuits, helping separate field-side signals from internal electronics.

6. Compact D-Shell Connection

The 37-pin D-shell connector provides a dedicated wiring interface for compatible field connections.

7. Space-Efficient System Expansion

By combining two I/O functions in one housing, the 1790-8BV8BX helps reduce the number of separate expansion blocks required in compatible installations.

Technical FAQs

Q1: How many I/O points does the 1790-8BV8BX provide?

It provides 16 total I/O points, consisting of eight universal digital inputs and eight sourcing digital outputs.

Q2: What input configurations are supported?

The eight input channels support both sinking and sourcing field-device configurations.

Q3: What is the nominal input voltage?

The nominal input voltage is 24 V DC, with an on-state voltage range of 9.6–28.8 V DC.

Q4: What is the maximum input current?

The maximum on-state input current is 8 mA per point at 28.8 V DC.

Q5: What type of output does the module use?

The module has eight non-isolated sourcing outputs designed for 24 V DC applications.

Q6: What is the maximum output current?

The maximum output current is 0.5 A per channel, with a maximum of 4.0 A per common. The connected loads must remain within these limits.

Q7: What is the output signal response time?

The maximum output delay is 0.5 ms from OFF to ON and 1.0 ms from ON to OFF.

Q8: Does the module provide channel-status indicators?

Yes. It includes green status indicators for the input and output channels, allowing technicians to monitor individual signal conditions.

Q9: What communication network does the 1790-8BV8BX use?

It belongs to the CompactBlock LDX DeviceNet I/O family. It operates as an expansion block connected to a compatible base module rather than as an independent network adapter.

Q10: What should be checked before replacing this module?

Verify the input wiring configuration, sourcing output requirements, field voltage, output current limits, connector arrangement, and compatibility with the existing CompactBlock LDX base block.

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