6
- 128
6.16 Watchdog Timer (WDT)
6
FUNCTIONS
(c) Scan time when WDT instruction is used
The scan time value is not reset even if the watchdog timer is reset in the
sequence program.
The scan time value is measured to the END instruction.
POINT
1. Scan time is the time from when the CPU module starts processing a
sequence program at Step 0 until it restarts processing another sequence
program with the same filename at Step 0.
The scan time is not consistent for each and changes depending on the
followings.
• Whether the commands used are executed or not executed.
• Whether to execute or not an interrupt program and a fixed scan
execution type program.
Note54
2. To execute at the same scan time at every scan, use the constant scan
function. (
Figure 6.84 Watchdog Timer Reset
Note54
Internal
processing time
Sequence program
Internal
processing time
Scan execution
type program A
Scan execution
type program B
WDT reset
(CPU module internal processing)
END
0
END
Scan execution
type program A
0
Scan time
Watchdog timer measured time
Next scan time
WDT reset
(CPU module internal processing
Basic
Note6.52
The Basic model cannot execute fixed scan execution type programs.
Basic
