Product Overview of the Allen-Bradley 1794-OB8EP

The Allen-Bradley 1794-OB8EP belongs to the 1794 Flex I/O family. This module provides eight sourcing DC outputs for field devices. The "EP" designation stands for Electronic Fuse protection. Each output channel has its own electronic fuse. This fuse disconnects the output automatically during a fault. The module mounts inside a terminal base unit. You can insert or remove modules under power. This feature saves time and avoids system restarts.

Technical Specifications

• Brand: Allen-Bradley / Rockwell Automation
• Part Number: 1794-OB8EP
• Product Type: Flex I/O Digital DC Output Module with Electronic Fuse
• Number of Outputs: 8 Sourcing Current Outputs
• Nominal On-state Voltage: 24V DC
• On-state Voltage Range: 19.2 to 31.2V DC
• Maximum Output Current Rating: 2A per Output
• Maximum Module Current: 10A total
• Maximum On-state Voltage Drop: 0.2V DC
• Maximum Off-state Leakage Current: 0.5 mA
• Maximum Output Delay Time: 0.1 ms (Off-to-On and On-to-Off)
• Isolation Voltage: 50V Continuous
• Flexbus Current: 73 mA at 5V DC
• Maximum Power Dissipation: 5.5W at 31.2V DC
• Maximum Thermal Dissipation: 18.8 BTU/hr at 31.2V DC
• External Power Supply: 19.2 to 31.2V DC with 5% AC ripple
• External Supply Current: 20 to 35 mA

Electronic Fuse Protection Feature

The main advantage of the 1794-OB8EP is its electronic fuse. Each output channel has independent overcurrent protection. The fuse disconnects the output when a fault occurs. This action protects both the module and field wiring. After the fault clears, you can reset the fuse electronically. There are no physical fuse elements to replace. This design reduces maintenance time and spare parts costs. The electronic fuse responds faster than traditional thermal fuses. Your system experiences less damage during wiring shorts.

Terminal Base Compatibility

The Allen-Bradley 1794-OB8EP works with several terminal bases. Compatible bases include the 1794-TB2, 1794-TB3, and 1794-TB3S. The 1794-TBN and 1794-TBKD bases also work perfectly. Choose the base that matches your wiring needs. The terminal base connects field devices to the output module. It also carries the Flexbus signals between modules. The module snaps directly onto the DIN rail mounting. No special tools are required for installation.

Output Performance and Switching Speed

This 1794-OB8EP module delivers fast output switching performance. The maximum output delay time is only 0.1 milliseconds. This speed applies to both Off-to-On and On-to-Off transitions. Fast switching supports high-speed machine control applications. The on-state voltage drop stays below 0.2V DC maximum. This low drop minimizes power loss and heat generation. The off-state leakage current stays below 0.5 mA. This low leakage prevents false activation of sensitive loads. Each channel handles up to 2A of continuous current. The entire module handles up to 10A total across all channels.

Communication and Network Options

The 1794-OB8EP works with various network adapters. You can use ControlNet for high-speed deterministic control. DeviceNet works well for device-level networks. EtherNet/IP provides standard Ethernet connectivity. Universal Remote I/O supports legacy system integration. The adapter determines the network protocol for the system. The output module simply responds to the Flexibus commands. This flexibility allows the same module in many systems.

LED Status Indicators

The 1794-OB8EP features 16 yellow LED status indicators. Each output channel has two dedicated LEDs. One LED shows the input device status. The other LED shows the actual output signal state. These LEDs provide instant visual feedback for operators. You can see channel status without a programming terminal. This feature speeds up field troubleshooting significantly.

Extreme Environment Options

The 1794-OB8EP has XT versions for harsh environments. XT modules operate in extreme temperatures and high humidity. They also resist corrosive atmospheres better than standard modules. Using XT versions reduces panel and maintenance costs. You avoid expensive external cooling or sealing cabinets. Choose the XT version for outdoor or unheated locations.

Installation and Mounting

Mount the 1794-OB8EP on a standard DIN rail. Simply snap the module onto the rail until it clicks. The module fits into any slot of the Flex I/O system. Ensure the terminal base is properly installed first. Push the Flexbus connector fully to connect with neighbors. You can remove or insert the module under power. This capability allows hot swapping without shutting down the system. Always follow proper electrostatic discharge precautions during handling.

Package Contents

• One (1) Allen-Bradley 1794-OB8EP Flex I/O Digital DC Output Module
• One (1) Installation Instructions Sheet

Common FAQs for the 1794-OB8EP

1. What does the EP suffix mean on the 1794-OB8EP?

The EP suffix on 1794-OB8EP stands for Electronic Fuse. Each output channel has an independent electronic fuse. This fuse disconnects the output automatically during an overcurrent fault.

2. How much current can each output on the 1794-OB8EP handle?

Each output on the 1794-OB8EP handles up to 2A maximum. The total module current is limited to 10A across all eight outputs. This rating applies at the nominal 24V DC supply voltage.

3. Which terminal bases work with the 1794-OB8EP module?

The 1794-OB8EP works with five terminal base models. These are the 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TBN, and 1794-TBKD. Choose the base that fits your wiring and space requirements.

4. Can I remove the 1794-OB8EP while the system is powered?

Yes, the 1794-OB8EP supports removal and insertion under power. This feature is called hot swapping. It saves time and avoids restarting the entire control system.

5. What is the switching speed of the 1794-OB8EP outputs?

The 1794-OB8EP has a maximum output delay of 0.1 milliseconds. This speed applies to both turning on and turning off. Fast switching supports high-speed machine control applications.