15
RAS FUNCTIONS
15.1
Scan Monitoring Function
This function detects hardware and program errors of the CPU module by monitoring the scan time. The watchdog timer, an
internal timer of the CPU module, is used to monitor the following scan.
• Initial scan (first scan)
• Second and later scans
Scan time monitoring time setting
Set the scan time monitoring time.
[CPU Parameter] [RAS Setting] [Scan Time Monitoring Time (WDT) Setting]
Window
Displayed items
Item
Initial Scan
After 2nd Scan
Watchdog timer reset
The watchdog timer is reset when the END/FEND instruction is executed. While the CPU module is running correctly, if the
END/FEND instruction is executed within the set time of the watchdog timer, the watchdog timer does not count up. If the
END/FEND instruction cannot be executed within the set time of the watchdog timer due to a hardware error of the CPU
module or increase in program execution time due to an interrupt or other causes, the watchdog timer counts up.
15 RAS FUNCTIONS
200
15.1 Scan Monitoring Function
Description
Sets the scan-time monitoring time (WDT) for the initial scan (first
scan).
Sets the scan-time monitoring time (WDT) for the second and later
scans.
Setting range
10 to 2000ms (in units of 10ms)
10 to 2000ms (in units of 10ms)
Default
2000ms
200ms