Mitsubishi FX3U Series Programming Manual page 338

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Table of Contents

Series Programmable Controllers

Programming Manual - Basic & Applied Instruction Edition

Comparison points

Make sure that the comparison value 1 and the comparison value 2 have the following relationship:

Comparison point

Comparison value 1

Comparison value 2

When the current value of the high speed counter C251 changes (counts) as shown below, the comparison

result is output to either of the outputs Y000, Y001 and Y002.

Comparison pattern

Related instructions

The following instructions can be combined with high speed counters:

1. Selection of the count comparison method

When DHSZ instruction is used, hardware counters (C235, C236, C237, C238, C239, C240, C244 (OP),

C245 (OP), C246, C248 (OP), C251 and C253) are automatically switched to software counters, and the

maximum frequency of each counter and the total frequency are affected.

Refer to the counting operation described below, and select according to the contents of control whether to

use DHSZ instruction or general-purpose comparison instruction.

1) Case to select DHSZ instruction

- When the output should be given when the counting result becomes equivalent to the comparison value

without regard to the scan time of the PLC

Contents (32 bits)

K2,147,483,647

Current value of C251

High speed counter set

High speed counter reset

High speed counter zone compare

High speed counter move

High speed counter compare with data table

13 High Speed Processing – FNC 50 to FNC 59

13.6 FNC 55 – HSZ / High Speed Counter Zone Compare

K1000 > C251

K1000 ≤ C251 ≤ K2000

Change of output contact (Y)

Instruction name

C251 > K2000

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