Mitsubishi Electric FX3G SERIES Programming Manual page 356

Programmable controllers

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Table of Contents

Series Programmable Controllers

Programming Manual - Basic & Applied Instruction Edition

4. Caution on the counting operation when the current value is changed

An instruction for the high-speed counter gives the comparison result when a pulse is input to the input (X) of the high-

speed counter.

However, the comparison result is not given when the current value of the high-speed counter is changed in the

following method:

Change method (examples)

a) Overwriting the contents of a word device used as the comparison value using DMOV instruction, etc.

b) Resetting the current value of a high-speed counter in a program

Even if the condition for setting the output to ON or OFF is given as the comparison result, the comparison result

does not change when an instruction is simply driven.

5. Reset operation by an external terminal [M8025

For a high-speed counter equipped with an external reset terminal (R) such as C241, an instruction is executed and

the comparison result is output at the rising edge of the reset input signal.

PLCs, high-speed counters operate in the HSC (external reset) mode regardless of the status of M8025.

If an instruction for the high-speed counter is used while M8025

the current value of the high-speed counter C241 is cleared by an external reset terminal. And the comparison

result is output even if a counting input is not given.

M8025 is cleared when the PLC mode is changed from RUN to STOP.

It is not necessary to drive M8025 in FX

When the external reset input X001 turns ON while the current value of C241 is "100", for example, the current

value of C241 is reset to "0". And Y000 is reset at this time even if a counting input is not given.

M8025 *1 External reset mode

13 High-Speed Processing – FNC 50 to FNC 59

13.4 FNC 53 – HSCS / High-Speed Counter Set

: HSC (external reset) mode]

is driven, the instruction is executed again when

External reset

terminal for C241

Fx3u series Fx3uc series