Allen-Bradley 1794-OE8H HART Output Module Overview

The Allen-Bradley 1794-OE8H is a Flex I/O HART analog output module. Specifically, it belongs to the 1794 series from Rockwell Automation. Therefore, this module provides HART communication over 4-20 mA loops. Consequently, users select the 1794-OE8H for controlling smart analog field devices. Moreover, the module features local microprocessor intelligence for advanced functions. Finally, it mounts on a terminal base with a keyswitch locking mechanism.

Technical Specifications of 1794-OE8H

The Allen-Bradley 1794-OE8H has 8 analog output channels. Specifically, the default output range is 0 to 20 milliamps. The current range can be set to 4 to 20 milliamps as needed. All 8 outputs are non-isolated from each other. Channel connections are electrical with shared references. The module includes power and I/O status indicators. Ambient temperature rating is 25°C ±5°C for specified operation.

The module features local microprocessor intelligence. Therefore, it can perform advanced functions without a controller. Lead breakage detection alerts users to wiring faults. Several data ranges are available for different applications. Alarms for remote transmitters are built into the module. Overrange and underrange detection is also included.

The 1794-OE8H operates without jumpers or switches. All configuration is done through software or HART commands. This simplifies installation and reduces setup errors. The module supports full HART communication on each channel. Therefore, users can access additional device data beyond the primary variable.

Mounting and Terminal Base Requirements

The Allen-Bradley 1794-OE8H requires a compatible terminal base. The keyswitch rotates until the module locks into place. Once the terminal base is wired, do not change the keyswitch position. Therefore, plan your wiring carefully before installation. The terminal base provides field wiring connection points. It also supplies the backplane interface to the Flex I/O adapter.

Installation Guidelines for Allen-Bradley 1794-OE8H

First, mount the terminal base on a standard DIN rail. Then, wire all field connections to the terminal base terminals. After that, rotate the keyswitch to the unlocked position. Next, insert the 1794-OE8H module into the terminal base. Subsequently, rotate the keyswitch to lock the module in place. Finally, apply power and verify the status indicators.

First, shut off all power before wiring the terminal base. Then, use shielded cable for all analog output wiring. Connect the shield drain wire to ground at one end only. For 4-20 mA loops, connect the output positive to the device positive. Connect the device negative to the output common return. Do not exceed 30V DC on any output channel. Finally, configure the output range using your control software or HART communicator.

Package Contents of 1794-OE8H

Your shipment includes these items:

One Allen-Bradley 1794-OE8H HART analog output module

One product installation instructions manual

Eight output channel identification labels

However, the package does not include the terminal base unit. Therefore, order a compatible base separately. Also, no mounting hardware is provided with this module. Finally, HART communicator is not included in the shipment.

Frequently Asked Questions about 1794-OE8H

1. What output ranges does the 1794-OE8H support?

The Allen-Bradley 1794-OE8H supports 0-20 mA and 4-20 mA ranges. Specifically, the default range is 0 to 20 milliamps. Therefore, configure the range based on your field device requirements. The 4-20 mA range is standard for most HART devices.

2. Are the outputs on the 1794-OE8H isolated from each other?

No, the 1794-OE8H has non-isolated output channels. Specifically, all 8 outputs share a common reference. Therefore, use external isolators if isolation is required. Group outputs that share the same power supply for best results.

3. Does the 1794-OE8H require jumpers or switches for configuration?

No, the Allen-Bradley 1794-OE8H operates without jumpers or switches. Specifically, all configuration is done through software or HART commands. Therefore, setup is simpler and more reliable. This also allows remote configuration changes.

4. What happens if the 1794-OE8H fails?

The 1794-OE8H cannot be repaired in the field. Specifically, it must be replaced or returned to the factory. Therefore, keep a spare module for critical applications. Contact your supplier for repair or replacement options.

5. What is the ambient temperature rating for the 1794-OE8H?

The Allen-Bradley 1794-OE8H has an ambient temperature rating of 25°C ±5°C. Specifically, this is the reference condition for specifications. Therefore, operate the module within this range for best accuracy. Derating may apply at temperature extremes.

Compatibility and Application Notes

The Allen-Bradley 1794-OE8H works with any Flex I/O communication adapter. Specifically, it mounts on a terminal base with a locking keyswitch. Use this module for controlling HART-enabled valves and positioners. The module includes lead breakage detection and alarm functions. HS code for customs is 85389000. Finally, store the module in a static-free environment before installation. Allen-Bradley and Rockwell Automation manufacture this product in the USA.