Allen-Bradley 1769-OF8C Analog Output Module

Product Introduction

The Allen-Bradley 1769-OF8C belongs to the 1769 Compact I/O family and provides eight single-ended current outputs. You can configure each channel for either 0-20 mA or 4-20 mA operation. This module integrates seamlessly with CompactLogix 1769, 1768, and MicroLogix 1500 controllers. It offers a 16-bit DAC resolution, ensuring precise signal generation for final control elements. Moreover, the 1769-OF8C includes comprehensive diagnostics like over-range and under-range reporting. Its built-in short-circuit and overvoltage protections enhance system reliability. This makes it a robust choice for demanding automation environments.

Technical Specifications

The 1769-OF8C delivers eight single-ended current outputs with a full-scale range of 0-21 mA and 3.2-21 mA. Its 16-bit unipolar resolution translates to 0.323 µA per bit, providing fine granularity. The module achieves a conversion rate of 5 ms across all channels simultaneously. Additionally, its step response reaches 63% of the final output in under 2.9 ms. This fast response suits applications requiring quick adjustments.

In terms of accuracy, the module holds ±0.35% of full scale at 25°C. It supports a resistive load of 0 to 500 Ω, including wire resistance. The maximum inductive load is 0.1 mH. For diagnostics, the 1769-OF8C reports open-wire conditions or high load resistance via bit reporting. It also detects over-range or under-range situations on each channel. The module dissipates 2.69 W of heat and requires no field calibration.

Furthermore, the output impedance exceeds 1 Ω, and the maximum short-circuit current is limited to 21 mA. This protection safeguards both the module and connected actuators. The module draws 145 mA at 5 VDC and 185 mA at 24 VDC. It uses a Delta-Sigma converter type for stable signal conversion. The overall accuracy remains consistent across the full operating temperature range of 0 to 60°C.

Mechanical and Environmental Parameters

The 1769-OF8C measures 4.65 inches in height, 1.38 inches in width, and 3.43 inches in depth. This single-width module fits easily into any 1769 I/O rack assembly. It weighs approximately 0.28 kg, making it lightweight for panel installation. The unit has no enclosure, so you must install it indoors only. Additionally, it operates reliably in environments with moderate vibration and humidity levels.

For wiring, the module accepts solid copper wire sizes from 22 to 14 AWG. It also supports stranded wire sizes from 22 to 16 AWG. The terminal block is finger-safe and removable, simplifying maintenance and replacement. A replacement door kit is available under part number 1769-RD. The module requires a 24 VDC external power supply and provides channel-to-earth ground isolation for enhanced noise immunity.

Installation Guidelines

First, mount the 1769-OF8C onto a DIN rail or panel inside a clean, dry control cabinet. Ensure the cabinet temperature stays within 0 to 60°C and humidity remains non-condensing. Next, connect the 24 VDC power supply to the designated terminals. Use twisted-pair shielded cables for the current output wiring to minimize electromagnetic interference.

Then, wire each output channel to the load device, observing correct polarity. The module supports both 2-wire and 4-wire configurations. For best results, route the wiring from beneath the module to the terminal block. After wiring, close the front door securely and apply power. The green status LED should illuminate, indicating normal operation. If the LED remains off, check the power connections and bus communication.

Application Scenarios

This analog output module commonly drives final control elements like modulating control valves, variable frequency drives, and positioners. It also sends signals to panel meters, data loggers, and signal splitters. When integrated with a PID controller inside the processor, the 1769-OF8C helps maintain precise process variables. Typical industries include oil and gas, water treatment, food processing, and manufacturing automation. Its fast conversion rate and diagnostic features make it suitable for critical loops where uptime is essential.

Packaging List

• Allen-Bradley 1769-OF8C analog output module (1 unit)

• Removable terminal block with finger-safe cover

• Installation instructions quick guide

• Module label and identification tag

Shipping Information

We ship this product via FedEx, UPS, or DHL. Delivery timelines depend on your location and selected service level. All shipments include tracking numbers for real-time monitoring.

Frequently Asked Questions

1. Can I use the 1769-OF8C with a MicroLogix 1500 controller?
Yes, the 1769-OF8C is fully compatible with MicroLogix 1500 systems. You can mount it as an expansion I/O module alongside the controller.

2. What happens if an output wire breaks during operation?
The module detects open-wire conditions within 5 milliseconds. It then reports this fault via bit reporting, allowing your control program to take corrective action.

3. Do I need to calibrate the 1769-OF8C after installation?
No, this module does not require field calibration. Factory calibration ensures consistent accuracy throughout its service life.

4. What is the maximum cable length for the current outputs?
While the module supports up to 500 Ω load resistance, cable length depends on wire gauge and total resistance. For 22 AWG wire, keep the length under 200 meters to stay within the load limit.

5. Can I mix 0-20 mA and 4-20 mA outputs on different channels?
Yes, each of the eight channels is independently configurable. You can set some channels for 0-20 mA and others for 4-20 mA as per your application needs.