Constant Scan - Mitsubishi Electric A800 Programming Manual

Constant scan

1.16

Constant scan

A constant scan time can be maintained for the sequence programs.
Configure the setting using FR Configurator2 (Developer).
PLC parameter
PLC RAS setting
• A waiting time is automatically set so that the sum of the execution time of the sequence programs and the waiting time is
equal to the set constant scan time.
• PLC parameter: Although the setting range of PLC RAS setting is 0.5 ms to 2000 ms, the actual set constant scan time is a
minimum of 10 ms. (Increments: 10 ms)
• I/O timing
After END processing is completed, a waiting time is automatically set as shown below.
NOTE
• Processes other than the PLC function are executed even during the waiting time.
• The set constant scan time must meet the following condition:
Set watchdog timer time > set constant scan time > maximum scan time of program.
• If a scan time is longer than the set constant scan time, "PRG.TIME OVER Error code: 5010" occurs. In this case, the
constant scan setting is ignored in the operation.
• If a scan time is longer than the set watchdog timer time, a watchdog timer error is detected and execution of the sequence
program stops. (Refer to
• Only the "Execute it while waiting for constant scan setting" is enabled for the service processing setting.
Settings other than "Execute it while waiting for constant scan setting" are ignored and no error occurs even if they are set.
• Scan time monitoring in FR Configurator2 (Developer) monitors the actual scan time excluding the waiting time for constant
scan.
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PLC Function
Name
Constant scan setting
Setting value
0.5 ms to 10.0 ms
10.5 ms to 20.0 ms
...
1990.5 ms to 2000.0 ms
Waiting time
Constant scan: operation when set to 7 ms.
page 35.)
Initial value Setting range
None 0.5 ms to 2000 ms
Set constant scan time
10 ms
20 ms
...
2000 ms
Program execution
END processing