Product Overview

The Allen Bradley 1790-16BV0X CompactBlock LDX Digital Input Expansion Module is a 16-point universal DC input expansion block used to acquire discrete signals from field devices in a CompactBlock LDX distributed I/O system. It operates with a nominal 24 V DC field supply and supports both sinking and sourcing input configurations, allowing it to interface with different types of industrial sensors and switching devices.

Unlike a standalone DeviceNet I/O module, the 1790-16BV0X does not have its own network adapter. It connects to a compatible CompactBlock LDX base block through an expansion ribbon cable. The base block handles communication with the PLC, while the expansion module adds 16 additional input channels to the existing I/O assembly.

A typical application involves a machine with several proximity sensors, photoelectric switches, limit switches, and push-button signals. These devices generate discrete ON/OFF signals that the PLC uses to determine equipment position, product presence, and machine operating conditions. The 1790-16BV0X provides additional input points for collecting these signals without requiring every field device to be wired back to the main control cabinet.

One of its main characteristics is the universal sinking/sourcing input configuration. Each input group can be wired according to the electrical arrangement of the connected field devices. This is useful in machine installations where sensors from different manufacturers or with different output configurations need to share the same I/O expansion assembly.

The 16 input channels are divided into two groups: inputs 0–7 and inputs 8–15. Each group has its own common-terminal arrangement, allowing the two sections to be configured independently for sinking or sourcing input operation.

For example, an automated packaging machine may use one group of inputs for three-wire PNP proximity sensors that detect product position, while the second group handles NPN sensor signals from another section of the machine. The appropriate common connections are selected for each group according to the sensor wiring arrangement.

The module uses a 37-pin D-shell connector for field wiring and includes 16 green input status indicators. These indicators provide a direct visual reference for individual input conditions. During commissioning, technicians can operate a sensor manually and check whether the corresponding input LED responds, making it easier to distinguish field wiring problems from PLC logic or communication issues.

Another important consideration is that the 1790-16BV0X is an expansion component rather than an independent controller interface. It must be installed with a compatible CompactBlock LDX base block. The expansion arrangement can support additional input capacity within the same distributed I/O assembly, subject to the base block’s expansion limitations.

The 1790-16BV0X is particularly useful in DeviceNet-based machine automation systems where the existing I/O installation needs more discrete input channels and the connected field devices require both sinking and sourcing compatibility.

Technical Specifications

Product Features

• 16 Universal Digital Inputs: Adds 16 additional input channels to a compatible CompactBlock LDX assembly.
• Sinking and Sourcing Compatibility: Supports both NPN and PNP sensor wiring arrangements through the appropriate common-terminal configuration.
• 24 V DC Operation: Uses a nominal 24 V DC field supply with an input operating range of 9.6–28.8 V DC.
• Two Independent Input Groups: Divides the 16 channels into two groups of eight for separate wiring configurations.
• Individual Input Indicators: Provides 16 green LEDs for checking the status of each input channel.
• 37-Pin D-Shell Interface: Provides the field wiring connection for external sensors and switching devices.
• Expansion Ribbon Cable Connection: Connects to a compatible CompactBlock LDX base block through the expansion interface.
• Compact Distributed I/O Design: Adds input capacity without requiring another independent DeviceNet network adapter.
• DIN Rail or Panel Mounting: Supports installation in industrial control panels and distributed I/O enclosures.
• Broad Sensor Compatibility: Accommodates compatible DC proximity sensors, photoelectric sensors, limit switches, and other discrete signal devices.

Working Principle

The 1790-16BV0X operates as a digital signal acquisition module within a CompactBlock LDX I/O assembly. Its function is to receive discrete electrical signals from field devices and make their input states available to the PLC through the connected base block.

The basic signal arrangement is:

Field Sensors / Switches → 1790-16BV0X → CompactBlock LDX Base Block → DeviceNet → PLC Controller

Discrete Signal Acquisition

When a connected sensor detects an object or reaches a switching condition, its output circuit changes state. The corresponding input channel on the 1790-16BV0X detects the electrical signal and updates its input status.

For example, a photoelectric sensor installed at the entrance of a packaging machine detects a passing product. Its 24 V DC output signal reaches one of the module’s input channels, allowing the PLC to recognize that a product has entered the packaging area.

The controller can then use this information to initiate the next machine operation, such as activating a conveyor stop or starting a packaging sequence.

Sinking and Sourcing Input Operation

One of the defining characteristics of the 1790-16BV0X is its ability to accept both sinking and sourcing input signals.

For sinking input wiring, the field device provides a current path toward the negative supply, and the corresponding input common is connected to the positive field supply.

For sourcing input wiring, the field device supplies positive voltage to the input circuit, and the corresponding input common is connected to field power negative (GND).

This arrangement allows different sensor output types to be connected to the same expansion module, provided each input group is wired correctly.

Independent Input Group Configuration

The 16 inputs are divided into two groups:

• Inputs 0–7 use COM0 and COM1.
• Inputs 8–15 use COM2 and COM3.

The common connections allow the two groups to be configured for the required sinking or sourcing arrangement.

For example, a machine may use PNP proximity sensors on inputs 0–7 and NPN sensors on inputs 8–15. The common connections can be arranged separately to accommodate these two sensor configurations.

This is particularly useful when retrofitting an existing machine where the installed sensors do not all use the same output wiring standard.

Input Signal Recognition

The module recognizes an ON state when the input voltage reaches the specified operating range. Its minimum ON-state voltage is 9.6 V DC, while the maximum specified OFF-state voltage is 5.0 V DC.

This distinction allows the module to differentiate between active and inactive field signals.

Each input channel also has an individual green status LED. When a valid input condition is detected, the corresponding indicator illuminates, providing a visual indication of the field signal.

Expansion Data Transfer

The 1790-16BV0X does not communicate directly with the PLC through an independent DeviceNet interface.

Instead, its input information is transferred through the expansion ribbon cable to the CompactBlock LDX base block. The base block manages the network communication and makes the additional input data available to the controller.

For example, a machine with an existing 16-point base I/O arrangement can add the 1790-16BV0X to accommodate more product-detection sensors and equipment-position switches. The controller can then process the additional input information as part of the distributed I/O configuration.

This arrangement expands the available signal acquisition capacity while retaining the existing network architecture.

Role in the CompactBlock LDX Control Architecture

The Allen Bradley 1790-16BV0X serves as an additional signal acquisition unit within the CompactBlock LDX distributed I/O architecture. It collects discrete field signals and transfers the input information through the base block to the controller.

A typical system arrangement follows this structure:

Field Sensors → 1790-16BV0X → CompactBlock LDX Base Block → DeviceNet Scanner → PLC Controller

In a typical production line, the base block communicates with the PLC through DeviceNet, while the 1790-16BV0X collects additional sensor signals from different machine sections.

For example, a packaging system may use several photoelectric sensors to detect product movement and limit switches to confirm the position of mechanical assemblies. The expansion module collects these discrete signals, allowing the PLC to coordinate conveyor movement, actuator operation, and safety-related machine sequencing through the appropriate control architecture.

Its universal input arrangement is particularly useful when the machine contains a mixture of sinking and sourcing DC sensors.

Industrial Applications

Installation and Maintenance

1. Verify the Module Model: Confirm that Allen Bradley 1790-16BV0X is the required 16-point universal DC input expansion module.
2. Check Base Block Compatibility: Ensure that the selected CompactBlock LDX base block supports digital expansion modules. Thermocouple and RTD base blocks do not support this expansion arrangement.
3. Inspect the Module: Check the housing, 37-pin D-shell connector, expansion interface, and mounting points for physical damage.
4. Prepare the Mounting Location: Select a suitable DIN rail or panel mounting position with sufficient space for field wiring and maintenance access.
5. Isolate the Power Supply: Disconnect power from the base block before installing the expansion module or modifying the expansion connection.
6. Mount the Expansion Module: Secure the module to the DIN rail or panel according to the intended installation arrangement.
7. Connect the Expansion Cable: Connect the ribbon cable between the base block and expansion module, ensuring that the red stripe on the cable faces downward.
8. Wire the Input Channels: Connect the field sensors to their assigned input terminals through the 37-pin D-shell connector, following the correct pin assignments.
9. Configure the Common Connections: Select the appropriate sinking or sourcing arrangement for inputs 0–7 and inputs 8–15 by wiring their respective COM terminals correctly.
10. Check Sensor Voltage Levels: Verify that the connected devices operate within the specified input voltage range and that inactive signals remain within the permitted OFF-state voltage.
11. Test Individual Input Points: Restore power and activate each sensor or switch individually. Check the corresponding green LED and confirm that the PLC receives the correct input status.
12. Document the Input Configuration: Record sensor assignments, input addresses, common-terminal wiring, and field power arrangements for future troubleshooting and maintenance.

Compatible System Components

Recommended Related Models

Key Advantages

• Adds 16 universal DC input channels to a compatible CompactBlock LDX assembly.
• Accepts both sinking and sourcing sensor signals.
• Supports a nominal 24 V DC field supply.
• Allows two groups of eight inputs to use separate common-terminal configurations.
• Provides 16 green input status indicators for signal monitoring.
• Supports proximity sensors, photoelectric sensors, and mechanical switches.
• Uses a 37-pin D-shell field wiring interface.
• Expands existing DeviceNet-based I/O capacity without requiring an independent network adapter.

Technical FAQs

Can the 1790-16BV0X accept both NPN and PNP sensor signals?

Yes. The module supports both sinking and sourcing DC input configurations. Inputs 0–7 and inputs 8–15 have separate common-terminal arrangements, allowing the two groups to be wired independently. This makes it possible to connect compatible NPN and PNP sensors within the same module, provided the common connections and field wiring are configured correctly.

What is the difference between the 1790-16BV0X and 1790-8BV8BX?

The 1790-16BV0X provides 16 universal digital input channels and is dedicated to signal acquisition. The 1790-8BV8BX combines eight universal input channels with eight sourcing digital output channels. The former is suitable when additional sensor inputs are required, while the latter is useful when a machine needs both additional input and output capacity.

How are the 16 input channels divided for wiring?

The inputs are arranged in two groups. Inputs 0–7 use COM0 and COM1, while inputs 8–15 use COM2 and COM3. Each group can be configured for sinking or sourcing input operation through the corresponding common connections. The internal common connections and D-shell pin assignments should be observed when preparing the field wiring.

Can the 1790-16BV0X work without a CompactBlock LDX base block?

No. It is an expansion module and does not contain an independent DeviceNet network adapter. It must connect to a compatible CompactBlock LDX base block through the expansion ribbon cable. The base block handles network communication and transfers the additional input information to the PLC.