Allen-Bradley 1756-OF8 ControlLogix Analog Output Module

The Allen-Bradley 1756-OF8 is an eight-channel analog output module for Rockwell Automation’s ControlLogix family, designed to convert PLC commands into precise analog signals to drive actuators, valves, and transducers in industrial automation. Each channel can be configured as either a voltage output (-10 to +10 V) or a current output (0 to 20 mA), providing flexibility for different sensor and actuator requirements. The module is a non-isolated analog output (outputs share a common reference with no isolation between channels) and uses a monotonic R-Ladder DAC for per-channel conversion. Key performance traits include high accuracy (calibrated to a tight full-scale range at 25 °C), fast settling, and a practical scan time suitable for real-time control loops. It wires to the ControlLogix backplane via the removable 1756-TBNH terminal block, enabling eight discrete outputs to be connected to field devices with standard 22–14 AWG conductors. In current-output mode, each channel can drive loads down to approximately 0 Ω up to the specified load limit, while in voltage-output mode the load is typically presented as a higher resistance, with the 750 Ω figure commonly cited as a practical limit for these outputs. The 1756-OF8 is designed for use in process control, motion, and automation applications where multiple precise analog signals are required from a single ControlLogix chassis.