Allen-Bradley 1794-IJ2 Flex I/O Frequency Module

Allen-Bradley 1794-IJ2 Flex I/O Input Module

Product Introduction

The Allen-Bradley 1794-IJ2 module is a specialized component within the Flex I/O system from Allen-Bradley. This Flex I/O Frequency Input Module precisely measures digital pulse signals from encoders, proximity switches, and flow meters. It supports a wide frequency range and provides configurable outputs for alarm or control actions. Its compact design and robust electrical isolation ensure dependable performance in harsh industrial environments.

Technical Specifications

The 1794-IJ2 module offers two independent input channels. Each channel includes a dedicated frequency input and a gate input. This architecture supports high-speed counting and period measurement applications with excellent precision.

• Input Frequency Range: 1 to 32 kHz (sine wave); 1 to 32 kHz (square wave)

• Input Pulse Width: 20 µs (minimum)

• Resolution: 0.01% to 0.00002% (depending on sample frequency)

• Sampling Accuracy: ±0.02% to ±0.00004%

• Number of Inputs: Two (2) frequency inputs; Two (2) gate inputs

• Number of Outputs: Two (2) isolated 24V DC outputs

• Output Voltage: 10V DC (minimum); 24V DC (nominal); 31.2V DC (maximum)

• Output On-state Current: 1.0 A per channel (maximum); Surge 2 A for 50 ms

Additionally, this module requires an external DC supply ranging from 19.0 to 31.2V DC. Its FlexBus current draw is only 30 mA at 5V DC. The module dissipates a maximum power of 4.6W at 31.2V DC, translating to a thermal dissipation of 15.6 BTU/hr. The raw frequency value can be scaled up to a maximum of 32,767 or 3,276.7, dependent on the selected range.

Mechanical and Environmental Parameters

The 1794-IJ2 operates reliably across a wide range of industrial conditions. Its mechanical design facilitates easy integration into standard control cabinets without specialized tools.

• Mounting: DIN Rail (using 1794-NM1 mounting kit)

• Terminal Base: 1794-TB3G or 1794-TB3GS

• Operating Temperature: 0 to 55 °C

• Wire Size: Determined by the installed terminal base

• Enclosure Type: Open-style

Furthermore, the module features LED indicators on the front panel. These include input status, output status, power status, and a wire-off fault indicator. An insertable label is also provided for writing individual I/O assignments, simplifying system documentation and maintenance.

Installation Guidelines

Installing the Allen-Bradley 1794-IJ2 is a straightforward process. First, ensure the FlexBus connector is fully inserted into the terminal base unit. Next, mount the module on a standard DIN rail using the recommended 1794-NM1 kit. Alternatively, you can use screw mounting for added flexibility in panel layouts.

After securing the module, connect the external power supply within the specified range of 19.0 to 31.2V DC. Then, wire the frequency and gate inputs according to your application requirements. Finally, configure the output channels. They can be individually assigned to trigger based on Frequency, % Full Scale, or Acceleration Alarm conditions. The output switching time is fast, with a turn-on time of 0.5 ms and a turn-off time of 1 ms.

Packaging and Logistics

Your order for the 1794-IJ2 module will include the following items:

• (1) Allen-Bradley 1794-IJ2 Flex I/O Frequency Input Module

• (1) Installation Instructions manual

Please note that the terminal base, mounting kit, and wiring are sold separately. All shipments are handled via trusted global carriers. We offer shipping through Fedex, UPS, DHL to ensure fast and secure delivery worldwide.

Frequently Asked Questions (FAQ)

1. What terminal base is compatible with the 1794-IJ2 module?
The 1794-IJ2 module requires either the 1794-TB3G or the 1794-TB3GS terminal base unit for proper installation and wiring.

2. Can this module measure both sine and square wave inputs?
Yes, the Allen-Bradley 1794-IJ2 accepts both sine wave and square wave inputs across its full frequency range of 1 to 32 kHz.

3. What is the maximum output current per channel?
Each isolated output on the 1794-IJ2 can source up to 1.0 A continuously, with a surge capacity of 2 A for 50 ms.

4. How do I mount the 1794-IJ2 module in a control cabinet?
You can mount the 1794-IJ2 on a standard DIN rail using the 1794-NM1 mounting kit, or use screw mounting for alternative panel installations.

5. What is the minimum input pulse width this module can detect?
The Allen-Bradley 1794-IJ2 reliably detects input pulses with a minimum width of 20 µs, ensuring accurate high-speed signal capture.