Chapter 4 CPU Function
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(2) Scan time differs in accordance with the execution or non-execution of interrupt progr
ams and communication processing, etc.
2) Scan time monitoring
Scan time is stored in the following system flag area.
• F50 : Maximum scan time (unit: 1 ms)
• F51 : Minimum scan time (unit: 1 ms)
• F52 : Current scan time (unit: 1 ms)
4.2.4 Scan Watchdog Timer
1) Watchdog timer is used to detect a delay which is attributable to abnormal operation of
sequence program. (Watchdog time is set in menu of basic parameter of KGLWIN.)
2) When watchdog timer detects an exceeding of preset watchdog time, the operation of P
LC option card is stopped immediately and all output is off.
3) If an exceeding of preset watchdog time is expected in sequence program, use ‘WDT’
instruction. ‘WDT’ instruction makes elapsed watchdog time to zero.
4) In order to clear watchdog error, restart the PLC option card or change mode to STOP.
Remark
- Setting range of watchdog : 10 ~ 6,000ms (unit : 10ms)
4.2.5 Timer Processing
The PLC option card use up count timer. There are 5 timer instructions such as On-delay
Timer (TON), Off-delay Timer (TOFF), Integral (TMR), Monostable (TMON), Retreggerable
(TRTG). The measuring range of 100msec timer is 0.1 ~ 6553.5 seconds, 10msec timer is
0.01 ~ 655.35 seconds.
Txxx Txxx xxxxx
Timer Preset Value
Timer Contact Number
Timer Type
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