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Appendix 4 Processing Time
Appendix 4.1 Concept of scan time
The concept of scan time in a multiple CPU system is the same as that in a single CPU system.
This section describes how to calculate the processing time when a multiple CPU system is configured.
(1) I/O refresh time
For the calculating formula of I/O refresh time, refer to the following.
User's Manual (Function Explanation, Program Fundamentals) for the CPU module used
The I/O refresh time increases by the time obtained by the following calculation when more than one CPU
module simultaneously accesses I/O modules and intelligent function modules through the bus .
Use the following value for N3.
(2) Total instruction execution time
For the processing time of the multiple CPU system dedicated instructions and the processing time of instructions
whose processing times differ between in a single CPU system and a multiple CPU system, refer to the following.
MELSEC-Q/L Programming Manual (Common Instruction)
QCPU
N3
System with a main base unit
only
System including extension
base unit(s)
Q00CPU, Q01CPU
8.7µs 21µs
Q02(H)CPU, Q06HCPU, Q12HCPU,
Q25HCPU
Q02PHCPU, Q06PHCPU, Q12PHCPU,
Q25PHCPU
Q00UCPU, Q01UCPU, Q02UCPU,
Q03UD(E)CPU, Q04UD(E)HCPU,
Q06UD(E)HCPU, Q10UD(E)HCPU,
Q13UD(E)HCPU, Q20UD(E)HCPU,
Q26UD(E)HCPU, Q50UDEHCPU,
Q100UDEHCPU
Q03UDVCPU, Q04UDVCPU,
Q06UDVCPU, Q13UDVCPU, Q26UDVCPU
(Extended time) =
(Number of input points + Number of output points)
16
N3 (Number of other CPU modules) (µs)