7 High-speed Counters
7-2
CJ2M CPU Unit Pulse I/O Module User’s Manual
7-1 Overview
High-speed counters are used to measure high-speed pulse input signals that cannot be measured by
counter (CNT) instructions.
z Applications
• Detecting the position or length of a workpiece with an input from an incremental rotary encoder.
• Measuring the speed of a workpiece from its position data using frequency measurement and
rotational speed conversion.
• High-speed processing according to the workpiece’s position data.
The present value of the high-speed counter is stored in the Auxiliary Area and can be used as posi-
tion data. When it reaches preset values, interrupts can be generated. The count can be started and
stopped. Depending on the instruction, the frequency (speed) can be read from the present value of
the high-speed counter.
7-1-1 Overview
Encoder
Phases A/B
Increment/decrement pulse input
Reset (phase Z) input
Changes the PV.
Target value
Interrupt task
Read
PRV
CTBL
Counter
input
High-speed counter
comparison
Read
Setting
Range comparison
upper/lower limits
• Setting target values or range
upper/lower limits, and starting
comparison and specifying the interrupt
task to be started
High-speed counter PV
(stored in Auxiliary Area)
• Reading PV (from Auxiliary Area or
using PRV(881) instruction)
• Reading frequency (using PRV
instruction)
Etc.
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