Rockwell Automation 1794-IJ2XT FLEX I/O Frequency Input Modules User Manual - Manual (Page 12)

Publication 1794-6.5.11 - September 2011
2 Overview of the Frequency Input Module
• I/O module – contains the bus interface and circuitry needed to
perform specific functions related to your application
The 1794 FLEX system consists of an adapter module, terminal base unit,
DIN rail, power supply, and adapter cabling components. You can use up to 8
terminal bases per adapter module.
For detailed instructions to set up and install your module, refer to the topic,
Install Your FLEX I/O Frequency Input Module, on page 13.
Type of Modules The FLEX I/O Frequency Input modules refer to the following catalogs.
The frequency input module is an intelligent I/O module designed to perform
high-speed frequency algorithms. The module provides:
• 2 Frequency Inputs,
• 2 Gate Inputs and
• 2 Outputs.
The Frequency Inputs can accept frequencies up to 32,767 Hz and it accepts
and returns binary data.
Usage of the Frequency
Input Module The FLEX I/O Frequency Input module is essentially a tachometer with the
capability of reporting frequency, acceleration, and direction. Outputs are
activated by alarms. Input devices range from magnetic pickup to flowmeters,
to incremental encoders to proximity detectors. This intelligent I/O module is
designed to perform high-speed frequency algorithms.
Power to the module is supplied from an external power supply. All power for
input devices (24V DC) is supplied by the I/O module. Outputs are used to
set alarms depending on the input conditions.
The module measures frequency over a user-specified time interval. A
frequency calculation can start before the time interval has elapsed, if a
user-specified number of frequency input pulses have occurred.
Catalog No. Voltage Inputs Outputs Description
1794-IJ2 24V DC 2 2 Digital – 2-pt 24V DC input frequency
module
1794-IJ2K 24V DC 2 2 Digital – 2-pt 24V DC input frequency
module, conformally coated.
1794-IJ2XT 24V DC 2 2 Digital – 2-pt 24V DC input frequency
module for extended temperature.