Allen-Bradley 1756-OF8 ControlLogix Analog Output Module

Allen-Bradley 1756-OF8 ControlLogix Analog Output Module

Product Introduction

The 1756-OF8 is a high-performance analog output module from the Allen-Bradley ControlLogix family. It features eight configurable output channels for voltage or current signals. This module is ideal for controlling actuators, valves, and recording instruments. It can be used as a local or distributed I/O module. Its robust design ensures accurate signal transmission in industrial environments.

Technical Specifications

The 1756-OF8 module provides eight analog output channels. Each channel is independently configurable for ±10V DC voltage or 0-20 mA current signals. This flexibility allows it to adapt to diverse application requirements. The module delivers a resolution of 15 bits across both ranges. Specifically, it offers 650 nA/bit for current and 320 µV/bit for voltage. Such precision ensures fine-grained control over connected devices.

This analog output module uses an R-Ladder DAC conversion method. It guarantees monotonicity with no missing codes. The 1756-OF8 supports two data formats: integer mode and IEEE 32-bit floating point. The scan time is 8 milliseconds for integer format and 12 milliseconds for floating point. This fast response is critical for dynamic control loops.

Furthermore, the module includes comprehensive protection features. It provides open circuit detection for current outputs. Short circuit protection electronically limits current to 21 mA or less. Overvoltage protection is rated at 24V DC. These safeguards enhance system reliability and prevent damage to connected equipment.

Electrical and Environmental Parameters

The 1756-OF8 draws a backplane current of 140 mA at 5V DC and 210 mA at 24V DC. Maximum power dissipation is 4.9 Watts at 60 °C. The module has an isolation voltage of 250V continuous between channels and backplane. It is tested with 1350V AC for 2 seconds using reinforced insulation.

In terms of accuracy, the module exhibits an offset drift of 50 ppm/°C and 0.1 ppm/°C. Gain drift is 25 ppm/°C for voltage and 50 ppm/°C for current. Overall module error is 0.15% in voltage mode and 0.3% in current mode. Therefore, it delivers consistent and trustworthy output signals.

The operating temperature range is 0 to 60 °C (32 to 140 °F). It functions at 5-95% non-condensing relative humidity. The module withstands a shock of 30G and vibration of 2G at 10-500 Hz. It carries temperature codes T4A (North America), T4 (ATEX), and T4 (IEC). The enclosure is open-style, suitable for cabinet mounting.

Wiring and Terminal Blocks

The 1756-OF8 requires removable terminal blocks for signal wiring. Compatible options are the 1756-TBNH and 1756-TBSH terminal blocks. When using the 1756-TBNH, single wire connection supports 0.33 to 2.1 mm² (22-14 AWG) copper wire. Double wire connection supports 0.33 to 1.3 mm² (22-16 AWG). The insulation rating must be 105 °C or greater.

For the 1756-TBSH, only single wire connection is applicable. It also supports 0.33 to 2.1 mm² (22-14 AWG) solid or stranded shielded copper wire. All wiring should use copper conductors rated at 105 °C. Proper wiring ensures optimal signal integrity and safety.

Installation Guidelines

Install the 1756-OF8 in any slot of a ControlLogix chassis. First, ensure system power is turned off before insertion. Align the module with the selected slot guides and slide it in firmly. Secure the module by tightening the retaining screws. Next, connect the appropriate terminal block for wiring. Wire each channel according to the output type required. Finally, apply power and configure the module using the ControlLogix configuration software.

Packaging List

The package for the 1756-OF8 includes the following items:

• Allen-Bradley 1756-OF8 ControlLogix Analog Output Module (1 unit)

• Installation instructions sheet (paper copy)

• Anti-static protective bag for safe transport

Shipping Information

All orders ship via FedEx, UPS, or DHL. These carriers provide reliable and trackable delivery worldwide.

Frequently Asked Questions

Q1: What types of output signals does the 1756-OF8 support?
The 1756-OF8 supports ±10V DC voltage signals and 0-20 mA current signals. Each of the eight channels can be configured individually for either type.

Q2: What is the resolution of the Allen-Bradley 1756-OF8 module?
This analog output module provides 15-bit resolution. For current, it is 650 nA/bit across 21 mA. For voltage, it is 320 µV/bit across 10.4V.

Q3: Which terminal blocks are compatible with the 1756-OF8?
The 1756-OF8 works with either the 1756-TBNH or 1756-TBSH removable terminal blocks. Both are sold separately.

Q4: Does the 1756-OF8 offer protection against short circuits?
Yes, the 1756-OF8 includes electronic short circuit protection. It limits the output current to 21 mA or less to prevent damage.

Q5: What is the scan time for the 1756-OF8 analog output module?
The scan time depends on the data format. It is 8 milliseconds for integer format and 12 milliseconds for IEEE 32-bit floating point format.