Allen-Bradley 1794-IP4 Flex I/O Pulse Counter Module Overview

The 1794-IP4 from Allen-Bradley is a high-speed Flex I/O pulse counter module. It provides four inputs organized in two groups of two channels, delivering precise counting for industrial applications. This module handles high-frequency pulses up to 100 kHz, ensuring reliable speed calculations, flow monitoring, and quantity measurements.

Input Specifications and Signal Requirements

Each input channel operates between 6 and 26.4 VDC. The minimum pulse width is 2 µs. Signals must pass cleanly through the 3–6 V transitional region. Improper signal levels can affect counting accuracy.

Power Supply and Current Ratings

The 1794-IP4 module accepts 12–24 VDC external power. It draws 150 mA at 12 VDC and 75 mA at 24 VDC nominally. Maximum power dissipation is 5 W at 26.4 VDC. Thermal dissipation reaches 17.1 BTU/hr at full load.

Dimensions, Mounting, and Terminal Bases

This Flex I/O module measures 1.8 × 3.7 × 2.1 inches and mounts easily on a DIN rail. Compatible terminal bases include 1794-TB2, 1794-TB3, 1794-TB3S, 1794-TBN, and 1794-TBKD. DIN rail mounting simplifies installation and maintenance.

Indicators and Wiring

The 1794-IP4 features eight yellow LED logic indicators and one red/green LED for power status. It uses Belden 8761 or equivalent wiring, supporting cable lengths up to 1000 ft (305 m) without signal degradation.

Industrial Applications and Communication

The module performs high-speed scaling, speed calculations, quantity counting, and flow monitoring. It supports ControlNet, DeviceNet, EtherNet/IP, and Universal Remote I/O networks. XT versions enable operation in extreme environments, reducing maintenance and panel costs.

Environmental and Mechanical Ratings

This module operates from 0 to 55°C and stores safely between -40 and 85°C. It withstands vibration up to 5 g at 10–500 Hz and operating shock of 30 g. These ratings ensure consistent performance in industrial conditions.

Summary of Key Specifications

• Inputs: 4 channels, 2 groups of 2 channels

• Max Pulse Frequency: 100 kHz

• Input Voltage: 6–26.4 VDC

• Power Supply: 12–24 VDC

• Current Consumption: 150 mA @ 12 VDC, 75 mA @ 24 VDC

• Power Dissipation: 5 W @ 26.4 VDC

• Thermal Dissipation: 17.1 BTU/hr

• Mounting: DIN Rail

• Dimensions: 1.8 × 3.7 × 2.1 in

• Terminal Bases: 1794-TB2, TB3, TB3S, TBN, TBKD

• LEDs: 8 logic, 1 power

• Environment: 0–55°C operating, -40–85°C storage

• Vibration/Shock: 5 g / 30 g