Is Your Legacy Control System Holding You Back?
Many plants still run PLC5 and SLC500 controllers that deliver solid performance. But when a discrete output module fails, production stops. The Allen-Bradley 1794-OB16P keeps those systems running without a full platform migration. This Flex I/O module provides sixteen sourcing outputs at 24VDC, so you can drive relays, solenoids, and indicator lamps with confidence. It mounts on a DIN rail and works with multiple communication adapters. That means you modernize at your own pace instead of replacing everything at once.
What Is the 1794-OB16P?
The 1794-OB16P is a Flex I/O discrete output module from Allen-Bradley. It delivers sixteen current-sourcing outputs. Each channel is electronically fused, which protects your wiring from short circuits. The module draws 60 mA at 5V DC from the Flexbus. It dissipates 5.0 W at 31.2V DC and produces 17.0 BTU/hr of thermal dissipation at the same voltage. You need a terminal base to install it. Compatible bases include the 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TB3K, and 1794-TB3SK. The module also works with the 1794-TBKD and 1794-TBN bases. Sixteen yellow status indicators show you channel states at a glance.
Key Technical Specifications That Matter
Output Capacity and Voltage
Each channel handles a minimum of 1.0 mA and a maximum of 500 mA. The total module current rating is 8.0A. The nominal on-state voltage is 24VDC, with a range of 10VDC to 31.2VDC. This flexibility lets you use standard industrial power supplies without precise tuning.
Surge and Leakage Performance
Every channel withstands a 2A surge for 50 ms. This surge is repeatable every 2 seconds. Off-state leakage maxes out at 0.5 mA. That low leakage prevents false triggering of sensitive loads.
Environmental Durability
The module operates from 0 to 55 C (32 to 131 F). Storage ranges from -40 to 85 C (-40 to 185 F). It handles 5g vibration at 10 to 500 Hz and 30g operating shock. These ratings suit typical factory floor conditions.
Isolation and Delay
The 1794-OB16P provides 50V continuous isolation. Output delay is 0.5 ms OFF to ON and 1 ms ON to OFF. These fast response times support high-speed sorting and packaging lines.
Where the 1794-OB16P Fits Best
Replacing Failed Modules in Legacy Lines
A food processing plant runs a PLC5 system with Flex I/O. When an output module fails, the line stops. The 1794-OB16P drops into the existing terminal base and restores operation. No rewiring is needed beyond the base connections. This approach avoids a costly controller upgrade.
Distributed Control in Manufacturing Cells
You can mix the 1794-OB16P with other Flex I/O modules. Use it with ControlNet, DeviceNet, PROFIBUS, or EtherNet/IP adapters. This flexibility lets you build distributed I/O architectures. Each cell controls its own outputs while the main controller oversees the process.
Driving High-Current Loads
With 500 mA per channel and 8A total, this module drives multiple relay coils or solenoid valves. The electronic fusing protects each channel independently. If one load shorts, the others keep working.
Installation and Setup
Mount the 1794-OB16P on a DIN rail using a compatible terminal base. Wire size depends on the terminal base you choose. The module requires an external DC supply of 10 to 31.2VDC with 5% AC ripple. Supply current ranges from 25 to 75 mA. Connect the Flexbus cable to power the internal circuitry. Verify all connections before applying power. Use the sixteen yellow indicators to confirm channel operation during commissioning.
Maintenance and Reliability
Inspect terminal base connections every six months for tightness and corrosion. Check for dust buildup on the module and clean with dry compressed air if needed. The electronic fusing eliminates replaceable fuses, which reduces spare parts inventory. Monitor the operating temperature to stay within the 0 to 55 C range. High ambient temperatures shorten module life. Keep cabinet ventilation clear. These practices maximize uptime and protect your investment.
Compatibility and Integration
The 1794-OB16P works with ControlLogix and CompactLogix controllers. It also supports legacy PLC5 and SLC500 systems. Communication adapters include ControlNet, DeviceNet, PROFIBUS, and EtherNet/IP. You can mix it with any Flex I/O module type. Configuration depends on the controller you use. This wide compatibility makes the 1794-OB16P a smart choice for mixed-vintage plants.
Selection Guide
Before ordering, confirm your existing terminal base model. You need one of these: 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TB3K, 1794-TB3SK, 1794-TBKD, 1794-TBN, or 1794-TBNK. Verify your field devices operate at 24VDC and draw less than 500 mA each. Check that your total load stays under 8A. SpareTechPLC stocks the 1794-OB16P and related Flex I/O components. Contact us to confirm availability and compatibility with your system.
Frequently Asked Questions
Can I use the 1794-OB16P with my existing PLC5 system?
Yes. The module works with PLC5 and SLC500 controllers through compatible Flex I/O adapters. Configuration depends on your specific controller and adapter combination.
What happens if one output channel shorts?
Each channel has electronic fusing. A short on one channel does not affect the others. The module continues operating on the remaining channels.
Do I need a separate power supply for the 1794-OB16P?
Yes. The module requires an external DC supply of 10 to 31.2VDC with 5% AC ripple. The Flexbus provides internal logic power only.
How many indicators does the module have?
The 1794-OB16P has sixteen yellow status indicators, one for each output channel.
What is the maximum current per channel?
Each channel handles up to 500 mA. The total module rating is 8.0A.
