Allen-Bradley 1756-OF8H Analog Output Module | 8-Channel, 4-20mA/0-20mA, 16-bit, Isolated Specs

Allen-Bradley 1756-OF8H Analog Output Module | 8-Channel, 4-20mA/0-20mA, 16-bit, Isolated Specs

Allen-Bradley 1756-OF8H ControlLogix analog output module specifications. 8-channel isolated analog output, 4-20mA/0-20mA, 16-bit resolution, IP20. For industrial process control.

Product Overview

The Allen-Bradley 1756-OF8H​ is a high-density isolated analog output module​ from the ControlLogix series, designed for precision process control applications. This module provides 8 isolated output channels​ with configurable 4-20mA or 0-20mA current outputs, 16-bit resolution, and operates on 24V DC power. The "1756" designation indicates the ControlLogix I/O module series, "OF8H" specifies the 8-channel isolated analog output high-density configuration. This module provides precise analog control signals for valves, actuators, drives, and other process control devices in demanding industrial applications.

Technical Specifications

Note: Specifications are based on Allen-Bradley 1756 series technical documentation. The "1756-OF8H" model specifically indicates 8-channel isolated analog output configuration. Actual specifications may vary slightly depending on production batch.

Model Number Decoding (1756-OF8H)

• 1756:​ Series designation (ControlLogix I/O module series)

• OF8:​ Module type (OF = isolated analog output, 8 = 8 channels)

• H:​ Configuration (H = high-density)

Note:​ The "OF" prefix indicates isolated analog output functionality. The "8" specifies 8 output channels. The "H" suffix indicates high-density configuration. This module is designed for use in ControlLogix chassis (1756-A4, A7, A10, A13, A17) and requires a ControlLogix processor for operation.

Key Features

• 8 Isolated Channels:​ Eight individually isolated analog output channels

• High Resolution:​ 16-bit resolution for precise control

• High Accuracy:​ ±0.05% of span accuracy for critical process control

• Fast Update Rate:​ 2 ms per channel typical update rate

• Configurable Outputs:​ Selectable 4-20mA or 0-20mA output ranges

• Channel Isolation:​ 250V AC isolation between channels and backplane

• Status Indicators:​ Comprehensive LED status for module and channels

• Diagnostic Features:​ Open wire detection and short circuit protection

• Removable Terminals:​ Spring clamp terminal blocks for easy wiring

• High-Density Design:​ Eight channels in single-slot footprint

• Industrial Grade:​ Designed for harsh industrial environments

• International Certifications:​ Multiple agency approvals for global use

Output Characteristics

Typical Applications

• Process Control:​ Control valve positioning in chemical and petrochemical plants

• Flow Control:​ Analog control of flow control valves

• Temperature Control:​ Control signal to temperature controllers and heaters

• Level Control:​ Control of level control valves in tanks and vessels

• Pressure Control:​ Control of pressure regulating valves

• Speed Control:​ Analog speed reference for variable frequency drives

• Position Control:​ Control of proportional valves for hydraulic/pneumatic systems

• Mix Ratio Control:​ Control of ingredient feed rates in batching systems

• pH/Conductivity Control:​ Control of chemical dosing pumps

• Analytical Instrumentation:​ Control signals for process analyzers

Important Technical Notes

1. System Requirements:​ Requires ControlLogix chassis and ControlLogix processor. Compatible with CompactLogix systems with 1769 adapter.

2. Output Configuration:​ Each channel independently configurable for 4-20mA or 0-20mA range. Configuration stored in module memory.

3. Load Resistance:​ Verify connected device impedance is within specified range. Exceeding maximum load resistance affects output accuracy.

4. Isolation:​ Each channel is isolated from others and from backplane. Maximum continuous isolation voltage is 250V AC.

5. Wiring:​ Use twisted, shielded pair cables for analog signals. Ground shield at one end only (typically at the module end).

6. Power Supply:​ Ensure adequate power supply capacity for both module operation and field device power requirements.

7. Environmental Conditions:​ Install in appropriate enclosure for protection. IP20 provides limited protection against dust and moisture.

8. Calibration:​ Factory calibrated. Field calibration possible with appropriate equipment and procedures.

9. Diagnostics:​ Open wire detection available for 4-20mA range. Short circuit protection is current limiting with auto-recovery.

10. Module Configuration:​ Requires configuration in ControlLogix programming software (RSLogix 5000/Studio 5000) for proper operation.

Note: For complete installation guidelines, wiring diagrams, configuration instructions, and detailed technical data, consult the official Allen-Bradley 1756 Series Technical Manual. Always verify the exact model number configuration with the manufacturer, as notation variations may occur.