6 RAS FUNCTIONS
6.1 Scan Monitoring Function
125
6
6 RAS FUNCTIONS
6.1 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]
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.
• When using the Process CPU (redundant mode), refer to the following as well.
Page 435 FUNCTIONS
• When using the SIL2 Process CPU, refer to the following as well.
Page 605 FUNCTIONS
Item Description Setting range Default
Initial Scan Sets the scan-time monitoring time (WDT) for the initial scan (first
scan).
10 to 2000ms (in units of 10ms) 2000ms
After 2nd Scan Sets the scan-time monitoring time (WDT) for the second and later
scans.
10 to 2000ms (in units of 10ms) 200ms
RnCPU
RnENCPU
RnSFCPU RnSFCPU
RnPSFCPU RnPSFCPU
RnPCPURnPCPU
(Standard) (Safety)(Standard) (Safety)
(Redundant)
(Process)
To Next Page
Loading...
