LSIS Master-K K1000S - Self-Diagnosis

Chapter 4 CPU modules MASTER-K
4-27
4.5.4 Self-diagnosis
1) WDT (Watch dog timer) function
The watch dog timer is an internal timer of a PLC to detect the error of hardware and a
sequence program. The default value is set as 200msec, and it is changeable with
parameter setting. Refer the MASTER-K programming manual for details on the
parameter setting.
The CPU resets the watch dog timer before step 0 is executed (after the END
processing is finished). When the END instruction has not been executed within the
set value due to an error occurred in the PLC or the long scan time of a sequence
program, the watch dog timer will times out. When a watch dog timer error is occurred,
all outputs of the PLC are turned OFF, and the ERR LED of the CPU will flashes.
(RUN LED will be turned OFF) Therefore, when use FOR ~ NEXT or CALL instruction,
insert WDT instruction to reset the watch dog timer.
2) I/O module check function
If one or more I/O modules are mounted/dismounted while the PLC is powered, the
corresponding bit (F0040 ~ F0050 : 32 bits) will be switched on. If a module is
mounted improperly, the relevant bit will be switched on also.
3) Battery check function
When the voltage of the battery for back-up the memory IC of CPU are lower than the
minimum back-up voltage, the BAT LED of CPU module will be turned on.
1 1 1
1 1 1
P
W
R
Slot No :
C
P
U
1 234567
Error occurred at slot 0
Error occurred at slot 1
Error occurred at slot 15
Error occurred at slot 31
F004
(word)
F005
(word)
MSB
MSB
LSB
LSB