Product Overview

The 1794-IJ2 is a Flex I/O frequency input module from Allen-Bradley. It provides two high-resolution frequency channels. Each channel has one frequency input and one gate input. This module is part of the 1794 Flex I/O system. It works with a rack-based configuration. The module uses a terminal base like 1794-TB3G. It also needs an adapter module for communication. The module has 2 inputs and 2 isolated outputs. It also has 2 frequency inputs. The front panel includes indicators for input, output, power, and wire-off fault. The module has a insertable label for writing assignments.

Application Scenarios

This module is ideal for processes that measure acceleration. It can also monitor direction or report frequency. Common uses include speed monitoring and frequency counting. The module supports high-speed algorithms. It works with units like accelerometers and tachometers. The outputs can trigger alarms based on frequency or acceleration. This makes it suitable for industrial automation. The module can integrate with Profibus or Ethernet networks via an adapter.

Technical Specifications

• Input frequency: 1 to 32 kHz for sine wave and square wave.
• Input pulse width: 20 µs.
• Raw frequency value max: 32,767 or 3,276.7 depending on range.
• Output voltage: 10 VDC min, 24 VDC nom, 31.2 VDC max.
• Output on-state current: 1.0 A per channel max. Surge current: 2 A for 50 ms.
• Power dissipation: 4.6 W max at 31.2 VDC. Thermal dissipation: 15.6 BTU/hr.
• FlexBus current: 30 mA at 5 VDC.
• External DC supply: 19.0 to 31.2 VDC (includes 5% AC ripple).
• Resolution: 0.01% to 0.00002% based on sample frequency (2 to 1000 ms).
• Sampling accuracy: ±0.02% to ±0.00004%.
• Mounting: DIN rail. Operating temperature: 0 to 55 °C.
• Maximum starting current: 10 A.
• Indicators: input, output, power, wire-off fault.

Installation & Maintenance Guide

Mount the 1794-IJ2 on a DIN rail. Use the 1794-NM1 mounting kit if needed. Fully insert the flex bus connector into the terminal unit. Secure the module with screws if not using DIN rail. Ensure correct terminal base (1794-TB3G or -TB3GS). Wire size depends on the installed terminal base. The inputs and outputs are electrically fused. This prevents damage from interrupted power supply. Maintenance includes checking the indicators. Clean the module periodically. Avoid exposure to extreme temperatures. Operate only within 0 to 55 °C. Follow the installation manual for detailed steps.

Packing List

The package includes one 1794-IJ2 module. It also contains a user manual. No terminal base is included. Terminal base must be purchased separately. This product ships via FedEx, UPS, or DHL.