When an Aging Line Demands Modern I/O
A packaging line running on a legacy PLC suddenly loses output channels. The maintenance team discovers the original discrete output card is obsolete, and production is losing thousands of dollars per hour. This is the exact scenario where the Allen-Bradley 1794-OB16 Flex I/O module becomes the difference between a quick recovery and a costly shutdown.
What Is the 1794-OB16?
The 1794-OB16 is a Flex I/O discrete DC output module from Allen-Bradley. It provides sixteen sourcing output channels, each rated for 24VDC nominal operation. The module communicates through any 1794 Flex I/O adapter, enabling distributed I/O architectures that reduce wiring runs and simplify panel layouts. It mounts on a DIN rail and uses an open-type enclosure.
Key Technical Specifications
Understanding the core parameters helps buyers confirm compatibility before ordering. The ON-state voltage ranges from 10VDC minimum to 31.2VDC maximum, with 24VDC nominal. Each channel handles a maximum ON-state current of 500mA, and the total output current rating across all sixteen channels is 8.0A. The maximum ON-state voltage drop is 0.5VDC, while the maximum OFF-state leakage current is 0.5mA. Isolation voltage reaches 50V continuous. The module draws 80mA at 5VDC from the FlexBus and dissipates up to 5.3W at 31.2VDC maximum. Thermal dissipation is 18.1 BTU/hr at 31.2VDC maximum. Sixteen yellow status indicators provide clear field-side diagnostics.
Where the 1794-OB16 Delivers Value
Material Handling Systems
Conveyor diverters, sortation gates, and actuator solenoids rely on reliable discrete outputs. The 1794-OB16’s 8.0A total capacity supports multiple simultaneous outputs without external relays in many applications.
Packaging and Labeling Equipment
The 0.5ms OFF-to-ON signal delay and 1ms ON-to-OFF delay keep high-speed packaging lines synchronized. Each channel’s 500mA maximum ON-state current suits valves, small contactors, and indicator lamps.
Replacement and Upgrade Projects
When legacy output cards fail, the 1794-OB16 offers a direct Flex I/O replacement path. It works with terminal bases including 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TB3K, and 1794-TB3SK. Up to eight modules can reside in a single Flex I/O rack.
Installation and Setup Guidance
Mount the module on a standard DIN rail. Select the appropriate terminal base for your wiring needs; wire size depends on the installed base. The 1794-OB16 uses keyswitch position 2. No internal fusing exists, so external fusing may be installed as required by the system. The recommended fuse for external fusing is SAN-O MQ4-800 mA. Verify all wiring against your system documentation before powering the module.
Maintaining Reliability Over Time
Operate the module within 0 to 55°C (32 to 131°F). Storage temperature ranges from -40 to 85°C (-40 to 185°F). The module withstands 5g vibration at 10 to 500 Hz and 30g operating shock. Inspect terminal connections periodically and follow the manufacturer’s safety manual for all maintenance activities.
Compatibility and Integration
The 1794-OB16 integrates with any 1794 Flex I/O adapter for distributed I/O applications. It also functions as local I/O for FlexLogix controllers or the FlexLogix Local I/O extender (1794-FLA). This flexibility makes it suitable for both new installations and retrofit projects where existing Flex I/O infrastructure is already in place.
Selection Checklist Before You Buy
Confirm your system uses Flex I/O architecture. Verify the required terminal base is available or already installed. Check that your power supply provides the 24VDC nominal voltage within the 10 to 31.2VDC range. Ensure external fusing meets your system requirements. SpareTechPLC supplies the 1794-OB16 and related Flex I/O components. Please verify current lifecycle status and availability with SpareTechPLC before ordering.
Frequently Asked Questions
How many output channels does the 1794-OB16 provide?
It provides sixteen sourcing output channels, each rated for 24VDC nominal operation with a maximum ON-state current of 500mA per channel.
What terminal bases work with this module?
Compatible terminal bases include 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TB3K, and 1794-TB3SK.
Can I use multiple 1794-OB16 modules in one rack?
Yes. Up to eight modules may be installed in a single Flex I/O rack.
Does the module include internal fusing?
No. The 1794-OB16 does not come with internal fusing. External fusing may be installed as required, and the recommended fuse is SAN-O MQ4-800 mA.
What is the operating temperature range?
The module operates from 0 to 55°C (32 to 131°F) with a storage range of -40 to 85°C (-40 to 185°F).
