Buy now: Allen-Bradley 1756-OF6CI ControlLogix Isolated Analog Current Module
Atlantechdrives provides you the 1756-OF6CI, a premium 6-channel analog current output module featuring individual channel-to-channel isolation. This module is the gold standard for heavy industrial process control where multiple current loops (4-20mA) must be managed without the risk of ground loops or electrical interference between channels. It is specifically designed to drive actuators and drives over long distances in electrically noisy environments.
- Channels: 6 Individually Isolated Current Outputs
- Output Range: 0-20mA or 4-20mA
- Isolation: 100% Channel-to-Channel and Channel-to-Backplane
- Resolution: 13-bit (approximately 2.7 microamps per count)
- RTB Required: 1756-TBNH or 1756-TBSH
The Advantage of Channel-to-Channel Isolation in the 1756-OF6CI
The 1756-OF6CI is engineered for reliability in the most demanding process plants. By providing 100% individual isolation for each of its six channels, it eliminates the need for external signal isolators. This is a massive advantage when controlling devices that may be powered by different transformers or located in different areas of a large facility. Ground potential differences that would destroy a non-isolated module are easily handled by the 1756-OF6CI. This module also provides advanced diagnostics, including open-circuit detection. If a wire breaks in a 4-20mA loop, the module immediately flags a fault in the controller, allowing for rapid troubleshooting before the process is negatively affected.
Expert Tips: Optimizing Long-Distance Current Loops
When using the 1756-OF6CI for long-distance current loops (up to 1000 meters), the loop resistance is your primary constraint. Ensure the total resistance of the cable plus the field device does not exceed 550 ohms. If you are operating at the edge of this limit, use 16 AWG wire to minimize voltage drop. Because this module is «Current Only,» it is exceptionally stable against electromagnetic interference (EMI) compared to voltage-based modules. However, always use twisted-pair cabling to further improve noise rejection, especially when the cables run parallel to high-power VFD output cables.
Maintenance and Hardware Longevity
Maintenance for the 1756-OF6CI should focus on loop integrity. Use the «Module Info» tab in Studio 5000 to monitor for «No Load» conditions. An annual inspection of the terminal block pins for any signs of heat stress is recommended, although the isolated nature of the module protects it from most external electrical surges. Since the module relies on the 24V DC backplane power to drive the current loops, ensure your chassis power supply has at least 25% spare capacity to handle the cumulative draw of six active 20mA loops plus the module’s internal logic consumption.
FAQs
Q: Does the 1756-OF6CI support voltage outputs?
A: No, the «CI» in the part number stands for Current Isolated. For voltage, you would need the 1756-OF6VI.
Q: What is the benefit of 6 channels over 4 or 8?
A: The 1756-OF6CI provides a unique balance of high density and individual isolation in a single-slot module.
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This isolated current output module provides precise control and pairs effectively with the 1756-IF6I analog input module.
