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372
FX
3G
/FX
3U
/FX
3UC
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
Operation
When the present value of the high speed counter C255 changes (counts) from "99" to "100" or from "101" to
"100", Y010 is reset (output refresh).
Related instructions
The following instructions can be combined with high speed counters:
Cautions
1. Selection of the count comparison method
1) FX
3U
/FX
3UC
PLC
When the HSCR instruction is used in FX
3U
/FX
3UC
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
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
K100 = C255
→
Y010
C255
K2,147,483,647
FNC 54
DHSCR
K100
C255
Y010
Reset.
Comparison
value
Comparison
source
Output
destination
M8000
RUN
monitor
M8000
FNC189
DHCMOV C251
D100
K0
RST
Y010
FNC229
LDD<= K10000
D100
M8000
FNC 50
REF
Y010
K8