The 1794-IJ2 is a high-resolution frequency input module from Rockwell Automation. It belongs to the Flex I/O family of distributed control components. This module processes two independent frequency channels with exceptional accuracy. Engineers rely on it for precise speed and direction measurement.
Product Summary
This module measures frequency from 1 to 32 kHz using sine or square waves. It features two isolated outputs that trigger alarms for frequency or acceleration events. The 1794-IJ2 operates on a 24V DC supply with a maximum power dissipation of 4.6W. Its resolution spans from 0.01% down to 0.00002%.
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This module delivers a raw frequency value up to 32,767. The value maximum changes to 3,276.7 depending on the selected range. It accepts an input pulse width of just 20 microseconds. This allows the module to capture very fast rotating equipment signals.
The sampling accuracy ranges from plus or minus 0.02% to plus or minus 0.00004%. This high accuracy depends directly on the chosen sample frequency setting. The sample frequency can adjust from 2 milliseconds up to 1000 milliseconds. This flexibility lets you optimize performance for your specific process.
Each input channel includes both a frequency input and a gate input. The gate input allows for precise gated counting or timing applications. The module uses a terminal base model 1794-TB3G or 1794-TB3GS. The wire size for installation depends entirely on the chosen terminal base.
The two isolated outputs provide robust control signaling capabilities. Each output can source up to 1.0 Ampere per channel maximum. The outputs can handle a surge current of 2 Amperes for 50 milliseconds. This surge is repeatable every 2 seconds for reliable alarm handling.
Output channels are individually assignable to frequency alarms. They can also be set for percent full scale or acceleration alarms. The output switching time is very fast for critical applications. Turn-on time is only 0.5 milliseconds with a turn-off time of 1 millisecond.
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This module solves the pain point of high-speed signal measurement in harsh environments. It accepts both sine wave and square wave inputs from various sensors. This compatibility reduces the need for additional signal conditioning hardware. It simplifies your procurement process and lowers overall system cost.
The module operates within an ambient temperature range of 0 to 55 degrees Celsius. Its maximum starting current is 10 Amperes for reliable power-up sequencing. The external DC supply range is 19.0 to 31.2 Volts DC. This wide range accommodates fluctuations in industrial power systems.
Mounting options include standard DIN rail installation. You can also use a 1794-NM1 mounting kit for screw mounting. The module features front panel indicators for input, output, and power status. A wire-off fault indicator helps technicians quickly diagnose connection issues.
The FlexBus current draw is only 30 mA at 5 Volts DC. This low current minimizes the load on your system power supply. The module is electrically fused on both inputs and outputs. This protection prevents damage during interrupted power supply events.
You can integrate this module using Profibus or Ethernet networks. This flexibility allows it to fit into existing control architectures easily. The module supports rack-based configuration with up to eight terminals. An adapter module manages the communication for the entire rack.
Logistics & Standard Packaging Details
- One Allen-Bradley 1794-IJ2 Flex I/O Frequency Input Module
- Standard anti-static packaging for safe transport
- Insertable label for writing individual I/O assignments
- Product documentation and installation guide included
- Express delivery shipping is available via FedEx, UPS, and DHL
