180
Timer and Counter Instructions Section 3-5
The Completion Flag is updated only when TMHH(540)/TMHHX(552) is exe-
cuted. The Completion Flag can thus be delayed by up to one cycle time from
the actual set value.
The present value of timers programmed with timer numbers 0000 to 2047 will
be updated even when the timer is on standby. The present value of timers
programmed with timer numbers 2048 to 4095 will be held when the timer is
on standby.
Timers will be reset or paused in the following cases. (When a timer is reset,
its PV is reset to the SV and its Completion Flag is turned OFF.)
Note (1) If the IOM Hold Bit (A500.12) has been turned ON, the status of timer
Completion Flags and PVs will be maintained when the operating mode
is changed.
(2) If the IOM Hold Bit (A500.12) has been turned ON and the status of the
IOM Hold Bit itself is protected in the PLC Setup, the status of timer Com-
pletion Flags and PVs will be maintained even when the power is inter-
rupted.
(3) The PV will be set to the SV when TMHH(540)/TMHHX(552) is executed.
When an operating TMHH(540)/TMHHX(552) timer is in a jumped program
section (JMP(004), CJMP(510), CJPN(511), JME(005)), the timer’s PV will
continue timing. (The jumped TMHH(540)/TMHHX(552) instruction will not be
executed, but the PV will be refreshed every 1 ms.)
When TMHH(540)/TMHHX(552) is in a program section between IL(002) and
ILC(003) and the program section is interlocked, the PV will be reset to the SV
and the Completion Flag will be turned OFF.
When a TMHH(540)/TMHHX(552) timer is forced set, its Completion Flag will
be turned ON and its PV will be set to 0000. When a TMHH(540)/
TMHHX(552) timer is forced reset, its Completion Flag will be turned OFF and
its PV will be reset to the SV.
The operation of the = Flag and N Flag depends on the model of the CPU
Unit. Refer to Flags, above, for details.
If online editing is used to convert a timer to another kind of timer with the
same timer number (such as TMHH(540)/TMHHX(552)
↔ TIM/TIMX(550) or
TMHH(540)/TMHHX(552)
↔ TIMH(015)/TIMHX(551)), be sure to reset the
Completion Flag. The timer will not operate properly unless the Completion
Flag is reset.
Condition PV Completion Flag
Operating mode changed from RUN or
MONITOR mode to PROGRAM mode or
vice versa.
1
0000 OFF
Power supply interrupted and reset
2
0000 OFF
Execution of CNR(545)/CNRX(547), the
RESET TIMER/COUNTER instructions
3
BCD: 9999
Binary: FFFF
OFF
Operation in interlocked program section
(IL(002)–ILC(003))
Reset to SV. OFF
Operation in jumped program section
(JMP(004)–JME(005))
PV continues
decrement-
ing.
Retains previous status.
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