166
Timers and Counters Section 4-13
The refresh method for timer PVs can be set from the CX-Programmer to
either BCD or binary.
Note It is not recommended to use the same timer number in two timer instructions
because the timers will not operate correctly if they are timing simultaneously.
(If two or more timer instructions use the same timer number, an error will be
generated during the program check, but the timers will operate as long as the
instructions are not executed in the same cycle.)
The following table shows when timers will be reset or maintained.
Note 1. If the IOM Hold Bit (A500.12) is ON, the PV and Completion Flag will be
retained when a fatal error occurs (including execution of FALS instruc-
tions) or the operating mode is changed from PROGRAM mode to RUN or
MONITOR mode or vice-versa. The PV and Completion Flag will be
cleared when power is cycled.
2. If the IOM Hold Bit (A50012) is ON and the PLC Setup’s IOM Hold Bit Sta-
tus at Startup setting is set to protect the IOM Hold Bit, the PV and Com-
pletion Flag will be retained when the PLC’s power is cycled.
3. Since the TIML(542), TIMLX(553), MTIM(543), and MTIMX(554) instruc-
tions do not use timer numbers, they are reset under different conditions.
Refer to the descriptions of these instructions for details.
4. The present value of TIM, TIMX(550), TIMH(015), TIMHX(551), TM-
HH(540), TMHHX(552), TIMW(813), TIMWX(816), TMHW(815) and TMH-
WX(817) timers programmed with timer numbers 0000 to 2047 will be
updated even when jumped between JMP and JME instructions or when
in a task that is on standby. The present value of timers programmed with
timer numbers 2048 to 4095 will be held when jumped or when in a task
that is on standby.
Forcing Bit Status Timer Completion Flags can be force-set and force-reset.
Timer PVs cannot be force-set or force-reset, although the PVs can be
refreshed indirectly by force-setting/resetting the Completion Flag.
Restrictions There are no restrictions in the order of using timer numbers or in the number
of N.C. or N.O. conditions that can be programmed. Timer PVs can be read as
word data and used in programming.
Instruction name Effect on PV and Completion Flag Operation in
Jumps and Interlocks
Mode change
1
PLC start-up
2
CNR(545)/CN
RX(547)
Jumps
(JMP-JME) or
Tasks on
standby
4
Interlocks
(IL-ILC)
TIMER: TIM/TIMX(550) PV → 0
Flag → OFF
PV → 0
Flag → OFF
PV → 9999
Flag → OFF
PVs refreshed in
operating timers
PV → SV
(Reset to SV.)
Flag → OFF
HIGH-SPEED TIMER:
TIMH(015)/TIMHX(551)
ONE-MS TIMER:
TMHH(540)/TMHHX(552)
ACCUMULATIVE TIMER:
TTIM(087)/TTIMX(555)
PV Maintained PV Maintained
TIMER WAIT:
TIMW(813)TIMWX(816)
PVs refreshed in
operating timers
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HIGH-SPEED TIMER WAIT:
TMHW(815)/TMHWX(817)
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