7 - 4 7 - 4
MELSEC-Q
7 FUNCTION
(c) The sequence program processing stops during the wait time from the last
END processing execution until the next scan starts.
1) If a low speed execution type program is executed, it will be interrupted
for - 0.5 ms (a constant scan time setting).
2) If an interrupt factor occurs after the END processing is performed, the
interrupt program or fixed scan execution type program is executed.
(d) Constant Scan Time Accuracy
This section describes the accuracy of a constant scan time setting.
1) The remaining portion (wait time) of a constant scan time setting is
0.02 ms on Q02CPU and 0.01 ms on Q02HCPU, Q06HCPU,
Q12HCPU, Q25HCPU when the following programs are not executed.
• low speed execution type program
• interrupt program
• fixed scan execution type program
2) Wait time is 0.5 ms when a low speed execution type program is used.
If the maximum processing time for one instruction in a low speed
execution type program is 0.5 ms, the remaining portion of constant
scan time is the same as described in 1). If the maximum processing
time exceeds 0.5 ms, constant scan delays for an excessive duration.
3) Interrupt is enabled while an interrupt program/fixed scan execution
type program is executed. If constant scan time runs out when an
interrupt program/fixed scan execution type program is executed,
constant scan cannot be finished. When an interrupt program/fixed
scan execution type program is used, constant scan time could be
shifted by the execution time of an interrupt program/fixed scan
execution type program.
REMARK
Refer to "QCPU (Q mode)/QnACPU Programming Manual (Common Instructions)"
for the command processing time.
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