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This bit can be programmed to activate an external warning for a low battery volt-
age.
The operation of the battery alarm can be disabled in the PC Setup if desired.
Refer to 3-6-4 PC Setup for details.
3-4-9 Cycle Time Error Flag
SR bit 25309 turns ON if the cycle time exceeds 100 ms. The ALM/ERR indicator
on the front of the CPU Unit will also flash. Program execution will not stop, how-
ever, unless the maximum time limit set for the watchdog timer is exceeded. Tim-
ing may become inaccurate after the cycle time exceeds 100 ms.
3-4-10 I/O Verification Error Flag
SR bit 25310 turns ON when the Units mounted in the system disagree with the
I/O table registered in the CPU Unit. The ALM/ERR indicator on the front of the
CPU Unit will also flash, but PC operation will continue.
To ensure proper operation, PC operation should be stopped, Units checked,
and the I/O table corrected whenever this flag goes ON.
3-4-11 First Cycle Flag
SR bit 25315 turns ON when PC operation begins and then turns OFF after one
cycle of the program. The First Cycle Flag is useful in initializing counter values
and other operations. An example of this is provided in 5-14 Timer and Counter
Instructions.
3-4-12 Clock Pulse Bits
Five clock pulses are available to control program timing. Each clock pulse bit is
ON for the first half of the rated pulse time, then OFF for the second half. In other
words, each clock pulse has a duty factor of 50%.
These clock pulse bits are often used with counter instructions to create timers.
Refer to 5-14 Timer and Counter Instructions for an example of this.
Pulse width 1 min 0.02 s 0.1 s 0.2 s 1.0 s
Bit 25400 25401 25500 25501 25502
Bit 25400
1-min clock pulse
Bit 25401
0.02-s clock pulse
Bit 25500
0.1-s clock pulse
Bit 25501
0.2-s clock pulse
Bit 25502
1.0-s clock pulse
Note:
Because the 0.1-second and
0.02-second clock pulse bits have
ON times of 50 and 10 ms, respec-
tively, the CPU Unit may not be
able to accurately read the pulses
if program execution time is too
long.
0.1 s
.05 s .05 s
1.0 s
0.5 s 0.5 s
0.2 s
0.1 s 0.1 s
1 min.
30 s 30 s
.02 s
.01 s .01 s
SR (Special Relay) Area Section 3-4