Mitsubishi Electric MELSEC FX3U Programming Manual page 374

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
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).
M8000
RUN
monitor
Related instructions
The following instructions can be combined with high speed counters:
Instruction
DHSCS
DHSCR
DHSZ
DHCMOV
DHSCT
Cautions
1. Selection of the count comparison method
1) FX /FX
3U 3UC
When the HSCR instruction is used in FX
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
M8000
FNC229
LDD<=
M8000
372
K2,147,483,647
C255
Comparison Comparison
value source
FNC 54
K100 C255
DHSCR
FNC No.
FNC 53 High speed counter set
FNC 54 High speed counter reset
FNC 55 High speed counter zone compare
FNC189 High speed counter move
FNC280 High speed counter compare with data table
PLC
FNC189
C251
DHCMOV
K10000 D100
FNC 50
REF
13 High Speed Processing – FNC 50 to FNC 59
13.5 FNC 54 – HSCR / High Speed Counter Reset
Output
destination
K100 = C255 → Y010
Y010
Instruction name
/FX PLCs, hardware counters (C235, C236, C237, C238,
3U 3UC
D100 K0
RST Y010
Y010 K8
Reset.