The Allen-Bradley 1794-IJ2 is a high-performance, dual-channel frequency input module engineered for the FLEX I/O 1794 platform. This module is designed to process high-speed pulse signals, providing real-time data on acceleration, velocity, and direction. By performing local signal processing, the 1794-IJ2 reduces the computational load on the central controller, ensuring low-latency performance in demanding industrial applications.
Features
Dual-Channel Processing: Features two independent channels, each equipped with a primary frequency input and a gate control input.
Broad Frequency Range: Capable of processing sine and square wave signals from 1 to 32 kHz.
Configurable Sample Windows: Supports user-defined sampling windows between 2 and 1000 ms, allowing for highly precise resolution adjustments.
Integrated Alarm Logic: Onboard hardware allows for direct mapping to frequency or acceleration alarms with a response time of 0.5 ms.
Diagnostic Capabilities: Includes front-panel LED indicators for status monitoring and wire-off fault detection to ensure system integrity.
Applications
This module is ideal for applications requiring precise monitoring of rotating machinery and flow systems, including:
Turbine flowmeter tracking
High-speed fan tachometer feedback
Web tension control systems
Rotating machinery diagnostic loops
Technical Specifications
Model
1794-IJ2
Inputs
2 Frequency / 2 Gate
Outputs
2 Sourced, Isolated
Frequency Bandwidth
1 to 32 kHz
Output Current
1.0 A per channel (continuous)
Response Time
0.5 ms (Turn-on) / 1.0 ms (Turn-off)
Power Supply
19.0 to 31.2 VDC
Operating Temp
0 to 55 deg C
Compatible Bases
1794-TB3G, 1794-TB3GS
Installation Guidelines
Ensure the module is installed on a compatible 1794-TB3G or 1794-TB3GS terminal base.
The module is designed for 35 mm DIN rail or direct panel mounting; ensure proper clearance for ventilation.
Always disconnect external power before inserting or removing the module from the terminal base to prevent electrical damage.
Use shielded cabling for input signals to minimize EMI interference in high-speed pulse applications.
Ensure the module is housed within an appropriate industrial enclosure, as it is an open-style device.
FAQ
Q: What is the primary function of the 1794-IJ2? A: It is a frequency input module that processes pulse trains locally to calculate speed, direction, and acceleration, offloading these tasks from the main PLC.
Q: Does this module require an external power supply? A: Yes, it requires an external 24 VDC power supply (19.0 to 31.2 VDC range) for operation.
Q: Can this module detect broken wires? A: Yes, the 1794-IJ2 includes a wire-off fault detection feature that alerts the system if an open-circuit condition occurs on the sensor lines.
