Allen Bradley 1756-CFM ControlLogix Flow Meter Module

Product Overview

The 1756-CFM (1756-CFM) is a high-precision configurable flowmeter module designed for the Allen-Bradley ControlLogix platform. Occupying a single slot in any standard ControlLogix chassis, this module serves as a specialized high-speed interface between the Logix controller and external pulse-producing flow sensors. It features two dedicated flowmeter inputs and two gate inputs, supporting complex liquid and gas measurement tasks such as totalizing and proving. With a maximum input frequency of 100 kHz, the 1756-CFM is engineered for high-resolution data acquisition in rapid-flow industrial processes.

Technical Specifications

• Manufacturer Rockwell Automation / Allen-Bradley

• Catalog Number 1756-CFM

• Series ControlLogix

• Input Configuration 2 Flowmeter Inputs, 2 Gate Inputs

• Maximum Input Frequency 100 kHz

• Flowmeter Input Voltage ±30V DC

• Selectable Input Thresholds 50mV, 1.3V, and 4V

• Input Impedance 5 kΩ

• Current Rating (IEC) 6–30 mA @ 24V DC

• Operational Modes Totalizer, Fill, and Prover

• Power Dissipation 6 Watts (Max @ 60°C)

• Backplane Current (5V DC) 300 mA

• Backplane Current (24V DC) 6 mA

• Removable Terminal Blocks (RTB) 1756-TBNH or 1756-TBSH

• Enclosure Type Open-style (Chassis mount)

Operational Modes & Applications

The 1756-CFM (1756-CFM) offers versatile processing modes tailored for the oil and gas, chemical, and food/beverage industries:

• Totalizer Mode Accurately tracks the cumulative volume of fluid passing through the flowmeter over a specified period.

• Fill Mode Enables precise batch control by triggering outputs or signals once a predetermined volume "fill" target is reached.

• Prover Mode Used for calibrating and verifying the accuracy of field flowmeters against a known standard.

• High-Speed Gating The two gate inputs allow for the precise starting and stopping of flow counts based on external process triggers.