Concept Of Scan Time - Mitsubishi Electric MELSEC-Q Series User Manual

11 PROCESSING TIMES OF THE BASIC MODEL QCPU

11.2 Concept of Scan Time

(1) I/O refresh time
(2) Processing time for instruction processed at END
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The scan time varies with the following elements.
• Number of I/O points
• Processing times of all instructions executed within one scan
• Sum of processing times of user interrupt program executed within one scan
• Processing for instruction processed at END
• Execution of various functions processed at END
• Module refreshes (e.g. refreshes made by MELSECNET/H, CC-Link, etc.)
• Service processing
• Constant scan setting (parameter setting)
The scan time is the sum of the following processing times.
(a) Refresh time of I/O data transferred from/to the following modules installed
on the main and expansion base units of the Basic model QCPU.
• Input module
• Output module
• Intelligent function module
(b) Calculate the I/O refresh time with the following expression.
(I/O refresh time) = (number of input points/16)
points/16)
Refer to the following table for N1 and N2.
CPU Type
Q3
Q00JCPU 2.5
Q00CPU 2.4
Q01CPU 2.3
(a) DUTY instruction
Time when the user timing clock (SM420 to SM424) specified for the DUTY
instruction is turned on/off at END processing
CPU Type
Q00JCPU
Q00CPU
Q01CPU
N1 + (number of output
N2
N1( s)
B Q6 B
3.3
3.2
3.1
END Processing Time (ms)
0.15
0.14
0.12
MELSEC-Q
N2( s)
Q3 B Q6 B
1.3 2.3
1.3 2.3
1.3 2.3
0.21
0.19
0.16
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