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FX3G/FX3U/FX3UC Series Programmable Controllers
Programming Manual - Basic & Applied Instruction Edition
13 High Speed Processing – FNC 50 to FNC 59
13.5 FNC 54 – HSCR / High Speed Counter Reset
Related instructions
The following instructions can be combined with high speed counters:
Cautions
1. Selection of the count comparison method
1) FX3U/FX3UC PLC
When the HSCR instruction is used in FX
3U/FX3UC PLCs, 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 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
HSCR instruction or general-purpose comparison instruction.
a) Case to select DHSCR 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
2) FX
3G PLCs
When the HSCR instruction is used in FX
3G PLCs, the total frequency of each counter is affected.
Refer to the counting operation described below, and select according to the contents of control whether to use
the HSCR instruction or a general-purpose comparison instruction.
a) Case to select the HSCR instruction
- When the output should be given if the counting result becomes equivalent to the comparison value
without regard to 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
Instruction FNC No. Instruction name
DHSCS FNC 53 High speed counter set
DHSCR FNC 54 High speed counter reset
DHSZ FNC 55 High speed counter zone compare
DHCMOV FNC189 High speed counter move
DHSCT FNC280 High speed counter compare with data table
M8000
FNC189
DHCMOV
C251 D100 K0
RST Y010
FNC229
LDD<=
K10000 D100
M8000
FNC 50
REF
Y010 K8
FNC229
LDD<=
K10000 C251 RST Y010
Y010 K8
FNC 50
REF
M8000