Settings For Execution Of Only One Sequence Program - Mitsubishi Q00JCPU User Manual

3
SEQUENCE PROGRAM CONFIGURATION AND
EXECUTION CONDITIONS

3.2 Settings for Execution of Only One Sequence Program

A sequence program performs operation from Step 0 to the END/FEND instruction.
It performs an END processing when the END/FEND instruction is executed.
After the END processing, operation restarts from Step 0.
As described above, the sequence program repeats the operation from Step 0 to the END/
FEND instruction.
(1) Scan time
Basic
Note3.14
Note14
Basic
The fixed scan execution type programs are not available for the Basic model QCPU.
Note3.14
POINT
This section explains the case where only one sequence program is created.
For creation of multiple sequence programs, the execution type can be specified
for each program, e.g. a program started only once at startup or a program
executed at fixed intervals.(
Scan time is a period from the time when the CPU module starts the sequence
program operation from Step 0 until it executes Step 0 of the same sequence program
again.
The scan time consists of the sequence program execution time and the END
processing time.
When either of the following programs is executed, the execution time of that program
is added to the scan time.
• Interrupt program
• Fixed scan execution type program
(a) Scan time storage location
The CPU module measures the current value and minimum and maximum values
of the scan time and stores them into the special registers (SD520, SD521,
SD524 to 527).
The scan time can be checked by monitoring SD520, SD521 and SD524 to 527.
Current value SD520
Minimum value SD524
Maximum value
SD526
When SD520 is 3 and SD521 is 400, the scan time is 3.4ms.
(b) Accuracy and measurement of scan time
The accuracy of each scan time stored into the special registers is
Even if the watchdog timer reset instruction (WDT) is executed in the sequence
program, the measurement of each scan time is continued.
3.2 Settings for Execution of Only One Sequence Program
Section 3.3)
Note3.14
Note14
SD521
SD525
SD527
Stores scan time of 1ms or less (unit s).
Stores scan time in 1ms units.
Diagram 3.17 Scan time storage location
1
2
3
4
5
6
7
0.1ms.
8
3
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