Is Your Control Cabinet Struggling to Deliver Reliable 24VDC Outputs?
Downtime often starts with an output module that cannot handle the load. The Allen-Bradley 1794-OB16 solves that problem. It is a Flex I/O discrete output module built for distributed control systems. This module provides sixteen sourcing output channels. Each channel operates at a nominal 24VDC. The 1794-OB16 belongs to the proven Flex I/O family from Allen-Bradley. It mounts on a DIN rail and works with multiple terminal base units. If you need dependable discrete outputs for a retrofit or a spare parts stock, this module deserves a close look.
Technical Specifications That Matter
The 1794-OB16 delivers 16 sourcing outputs. The ON-state voltage range runs from 10VDC minimum to 31.2VDC maximum. Nominal voltage is 24VDC. The total output current rating reaches 8.0A. Each channel handles up to 500mA. The maximum ON-state voltage drop is 0.5VDC. Off-state leakage current stays at or below 0.5mA. Isolation voltage is rated at 50V continuous. The module draws 80mA at 5VDC from the FlexBus. Maximum power dissipation is 5.3W at 31.2VDC. Thermal dissipation reaches 18.1 BTU/hr at 31.2VDC. Sixteen yellow status indicators show field-side status at a glance. The module measures 3.7 x 3.7 x 2.7 inches and weighs approximately 78 grams. Operating temperature ranges from 0 to 55°C (32 to 131°F). Storage temperature spans -40 to 85°C (-40 to 185°F). Vibration tolerance is 5g at 10 to 500 Hz. Operating shock rating is 30g.
Where the 1794-OB16 Fits Best
Discrete Output Control in Distributed Systems
This module works with any 1794 Flex I/O adapter. That makes it ideal for distributed I/O applications. You can place outputs close to the field devices. This reduces wiring runs and installation cost. Up to eight 1794-OB16 modules may be installed in a single Flex I/O rack. That density saves panel space.
Local I/O for FlexLogix Controllers
The 1794-OB16 also functions as local I/O for a FlexLogix controller. It can serve the FlexLogix Local I/O extender (1794-FLA) as well. This flexibility helps when you need to expand an existing FlexLogix system without a full platform change.
Replacement and Upgrade Scenarios
When an existing output module fails, the 1794-OB16 offers a direct fit. It uses the same terminal bases and mounting style. That means less downtime during changeover. SpareTechPLC stocks this module for buyers who need a fast replacement.
Installation and Setup
Mount the 1794-OB16 on a DIN rail. Select a compatible terminal base: 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TB3K, or 1794-TB3SK. Wire size depends on the installed terminal base. The module uses keyswitch position 2. It has an open-type enclosure. This module does not include internal fusing. External fusing may be installed as required by your system. The recommended fuse for external fusing is the SAN-O MQ4-800 mA. Follow your site’s wiring standards and the manufacturer’s installation manual.
Maintenance and Reliability
Inspect the module periodically for loose connections and indicator status. The sixteen yellow LEDs help you spot a failed channel quickly. Keep the cabinet within the operating temperature range of 0 to 55°C (32 to 131°F). Ensure adequate airflow around the DIN rail. The 30g shock and 5g vibration ratings suit most industrial environments. For safety-related systems, follow the manufacturer’s safety manual and inspect at recommended intervals. Because this module has no internal fusing, verify external fusing is intact during routine checks.
Compatibility and Integration
The 1794-OB16 integrates with any 1794 Flex I/O adapter. It supports distributed I/O architectures. It also works as local I/O for FlexLogix controllers and the 1794-FLA extender. The module uses sourcing output wiring. Confirm your field devices match this configuration. The 50V continuous isolation rating protects the system from signal interference. The FlexBus current draw of 80mA at 5VDC must be included in your power budget.
What to Verify Before Buying
Check that your application needs 24VDC sourcing outputs. Confirm you have a compatible terminal base on hand. Verify the total load does not exceed the 8.0A output current rating. Each channel should stay within the 500mA maximum. If you need external fusing, source the SAN-O MQ4-800 mA fuse. SpareTechPLC provides this module and related Flex I/O components. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
Frequently Asked Questions
Can I use the 1794-OB16 with any Flex I/O adapter?
Yes. The module is compatible with any 1794 Flex I/O adapter for distributed I/O applications.
How many 1794-OB16 modules fit in one Flex I/O rack?
Up to eight modules may be installed in a single Flex I/O rack.
Does the 1794-OB16 have internal fusing?
No. The module does not come with internal fusing. External fusing may be installed as required. The recommended fuse is the SAN-O MQ4-800 mA.
What is the maximum current per output channel?
Each channel supports a maximum ON-state current of 500mA. The total output current rating for all 16 channels is 8.0A.
Which terminal bases work with this module?
Compatible terminal bases include 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TB3K, and 1794-TB3SK.
