Overview
The Allen-Bradley 1771-CFM is a single-slot configurable flowmeter module designed for high-speed flow measurement and shaft speed applications in PLC-5 automation systems. This I/O module interfaces between any Allen-Bradley PLC processor that has block-transfer capability and external I/O devices. 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.
Key Features
- Four input channels that can control up to four outputs, with four selectable operating modes: non-resettable totalizer, totalizer, high-resolution frequency, and direction sensor.
- Supports frequencies as high as 100 kHz and counts as large as 9,999,999.
- Single-slot installation in chassis, protected from corrosive chemicals by conformal coating.
- Supports high-speed totalizing and frequency calculation operations, helping increase throughput while reducing the burden on the PLC processor.
- Four digital outputs operate at 5 to 40 Volts DC voltage.
Technical Specifications
- Input Channels: 4
- Input Voltage: 50 mV–200 VAC Peak (Magnetic Pickup); 5–40 VDC (TTL Compatible)
- Output Voltage: 5–40 VDC
- Output Current: 1 A per channel
- Backplane Power Current: 1 Amp
- Power Dissipation: 2 to 13 Watts
- Maximum Input Frequency: 100 kHz; Maximum Count Value: 0 to 9,999,999 (programmable); Maximum Processing Time: 5.5 milliseconds
- Operating Temperature: 0°C to +60°C (32°F to +140°F)
- Slots Required: 1
- Compatible with Bently 3300 proximity pickups
Typical Applications
The 1771-CFM is widely used in power generation, automotive, food processing, and fluid transfer industries where precision flow measurement and shaft speed monitoring are critical. Applications include:
- Turbine flowmeter integration for precise volume/rate measurement
- Shaft encoder and speed monitoring for rotating equipment
- Magnetic pickup sensing for non-contact flow detection
- Prover calibration and pulse-count capture during meter commissioning
- Process control requiring real-time frequency calculation offloaded from the CPU
Compatibility & Replacements
Compatible With
- Allen-Bradley PLC processors with block-transfer capability
- 1771-A1B, A2B, A3B, A3B1, A4B (series A and B) I/O chassis, 1771-AM1, AM2 I/O chassis with integral power supply
- Magnetic pickup sensors and TTL input sources
- Shaft encoders and turbine flowmeters
Replaces / Drop-In Replacement For
- 1771-QRC and 1771-QRD modules — can be used as a direct replacement by setting the CFM module’s operation jumper and wiring I/O devices to the new field wiring arm, with no changes to ladder logic required.
Works With
- PLC-5 block-transfer programming instructions
- RSLogix 5 ladder logic development software
- Allen-Bradley I/O chassis and backplane systems
- External flow measurement and sensing devices via analog/digital inputs
