Mitsubishi Electric FX3G SERIES Programming Manual page 363

Programmable controllers

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Table of Contents

Series Programmable Controllers

Programming Manual - Basic & Applied Instruction Edition

1. Selection of the count comparison method

When the HSZ instruction is used in FX

C240, C244 (OP), C245 (OP), C246, C248 (OP), C251 and C253) are automatically switched to software

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

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

the DHSZ instruction or general-purpose comparison instruction.

a) Case to select the DHSZ instruction

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

regardless of the scan time of the PLC

b) Cases to select a general-purpose comparison instruction

When the frequency is beyond the counting performance of software counters (and below the counting

performance of hardware counters)

When counting is important, but the effect of the scan time can be ignored in operations depending on the

counting result

When the number in an instruction is more than 32

LDD <= K10000

When the HSZ instruction is used in FX

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

the HSZ instruction or a general-purpose comparison instruction.

a) Case to select the HSZ instruction

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

regardless of the scan time of the PLC

b) Cases to select a general-purpose comparison instruction

When counting is regarded as important, but the effect of the scan time can be ignored in operations

according to the counting result

When an instruction is used 6 times or more

ANDD >= K20000

PLCs, the total frequency of each counter is affected.

13 High-Speed Processing – FNC 50 to FNC 59

13.6 FNC 55 – HSZ / High-Speed Counter Zone Compare

PLCs, hardware counters (C235, C236, C237, C238, C239,

Fx3u series Fx3uc series