Mitsubishi Electric FX3G SERIES Programming Manual page 356

FX /FX /FX Series Programmable Controllers
3G 3U 3UC
Programming Manual - Basic & Applied Instruction Edition
4. Caution on the counting operation when the current value is changed
An instruction for the high-speed counter gives the comparison result when a pulse is input to the input (X) of the high-
speed counter.
However, the comparison result is not given when the current value of the high-speed counter is changed in the
following method:
1) Change method (examples)
a) Overwriting the contents of a word device used as the comparison value using DMOV instruction, etc.
b) Resetting the current value of a high-speed counter in a program
2) Operation
Even if the condition for setting the output to ON or OFF is given as the comparison result, the comparison result
does not change when an instruction is simply driven.
5. Reset operation by an external terminal [M8025
For a high-speed counter equipped with an external reset terminal (R) such as C241, an instruction is executed and
the comparison result is output at the rising edge of the reset input signal.
In FX PLCs, high-speed counters operate in the HSC (external reset) mode regardless of the status of M8025.
3G
1) Program
If an instruction for the high-speed counter is used while M8025
the current value of the high-speed counter C241 is cleared by an external reset terminal. And the comparison
result is output even if a counting input is not given.
M8000
RUN monitor
*1. M8025 is cleared when the PLC mode is changed from RUN to STOP.
It is not necessary to drive M8025 in FX
2) Operation
When the external reset input X001 turns ON while the current value of C241 is "100", for example, the current
value of C241 is reset to "0". And Y000 is reset at this time even if a counting input is not given.
354
M8025 *1 External reset mode
X001
K9,999
C241
FNC 54
K 0 C241
DHSCR
PLCs.
3G
13 High-Speed Processing – FNC 50 to FNC 59
13.4 FNC 53 – HSCS / High-Speed Counter Set
*1
: HSC (external reset) mode]
*1
is driven, the instruction is executed again when
External reset
terminal for C241
Y000