Overview
Allen-Bradley 1771-CFM is a single-slot I/O module designed for precise flow and shaft-speed measurement in PLC-5 automation systems. The CFM module interfaces Allen-Bradley programmable logic controllers (PLCs) with magnetic pickups, single-channel shaft encoders, turbine flowmeters or any source of TTL pulses to measure flow and shaft speed. Frequencies as high as 100kHz and counts as large as 9,999,999 are supported. The module performs high-speed totalizing and frequency calculations without burdening the PLC processor.
Key Features
- 4 Configurable Input Channels: Measure speed or frequency, measure counts or volume, interface to a prover, or measure the direction of shaft rotation (uses two input channels).
- 4 Assignable Output Channels: Control outputs triggered by calculated flow totals and frequency values with software-selectable turn-on and turn-off thresholds.
- Direct Replacement Capability: You can use the CFM module as a direct replacement for your 1771-QRC or 1771-QRD module by setting the CFM module’s operation jumper and wiring your I/O devices to the new field wiring arm. When you use the CFM module as a direct replacement, you continue to program your block transfer instructions as before; no changes to ladder logic are necessary.
- High-Speed Totalizer & Frequency Modes: Supports non-resettable totalizer, totalizer, high-resolution frequency, and direction sensor modes.
- Magnetic Pickup & TTL Input Support: Compatible with magnetic pickups, Bently 3300 proximity sensors, shaft encoders, and TTL pulse sources.
Technical Specifications
- Input Channels: 4 digital inputs (50 mV–200V AC peak magnetic pickup, 4–40V DC TTL compatible)
- Output Channels: 4 digital outputs (5–40V DC, user-supplied)
- Maximum Input Frequency: 100 kHz
- Maximum Count Range: 0 to 9,999,999 (programmable)
- Module Scan Time: 1.3–5 milliseconds
- Processing Time: 5.5 milliseconds maximum
- Backplane Current Load: 1.0 A maximum
- Power Dissipation: 2–13 Watts
- Slot Requirement: 1 slot in I/O chassis
- Operating Temperature: 0–60°C (32–140°F)
- Input Voltage (User-Supplied): 5–40V DC
- Certifications: UL, CSA, CE, C-TICK, Marine
- Backplane Power Current: 1.0 A max
- Module DC Source Output: 24V DC, 12mA, 5% ripple
Typical Applications
The CFM module can be used in the power generation, automotive, food processing, chemical, pharmaceutical, water/wastewater treatment, and renewable energy industries. Applications include turbine flowmeter measurement, liquid prover calibration capture, shaft-speed monitoring for rotating equipment, magnetic-pickup frequency counting, and totalizing pulse inputs for batch or continuous processes.
Compatibility & Replacements
Compatible With
- PLC-5 Programmable Controllers (all models with block-transfer capability)
- 1771 series I/O Chassis: 1771-A1B, A2B, A3B, A3B1, A4B (Series A & B)
- 1771-AM1 & AM2 I/O Chassis with integral power supply
- Magnetic pickup flowmeters & shaft encoders (TTL or analog)
- Bently Nevada 3300 proximity sensors (5mm & 8mm)
- Turbine flowmeter & pulse-generating devices
Replaces / Drop-In Replacement For
- 1771-QRC Configurable Module
- 1771-QRD Configurable Module
Works With
- PLC-5 and PLC-5/250 programming environments
- Block transfer instructions (no ladder logic changes required)
- Allen-Bradley RSLogix and earlier automation software
- Magnetic pickup sensors & TTL pulse inputs up to 100 kHz
