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MELSEC-Q
18 PROCESSING TIME FOR MULTIPLE PLC SYSTEM HIGH
PERFORMANCE MODEL QCPUS
18.2 Factor to Prolong the Scan Time
The processing time for multiple PLC systems is prolonged in comparison with single
CPU systems when the following functions are used.
Add the following values to the values calculated in Sections 11.1 and 18.a to acquire
the amount of time used by these functions.
• Multiple PLC system automatic refresh
• MELSECNET/H refreshing
• CC-Link automatic refresh
(1) Automatic refresh of CPU shared memory
(a) The amount of time required to perform the refresh function set up with the
multiple PLC settings.
This value is the total amount of time required for writing into the host PLC's
CPU shared memory, and the amount of time required to read from other
PLCs' CPU shared memories.
These values are added when setting up the refresh settings with the PLC
parameter multiple PLC settings.
(b) The automatic refresh period of the CPU shared memory is calculated in the
following equation.
(Automatic refresh time) = (N1 + (received word points) N2) (number of other
PLCs) + (N3 + (transmitted word points) N4) ( s)
• The received word points must equal the word points transmitted by other PLCs.
For example, if the host PLC is the PLC No.1, then this value must equal the number of
points transmitted for the PLC No.2 to PLC No.4.
• Use the following values for N1 to N4.
CPU type
N1
N2
N3
N4
Q02CPU
82
s
0.52
s
106
s
0.17
s
Q02HCPU, Q06HCPU, Q12CPU, Q25HCPU
27
s
0.44
s
27
s
0.08
s
(c) The amount of time required for the automatic refresh process will be
prolonged by the following amount of time when processing is duplicated
with the automatic refresh function on other PLCs.
(Prolonged time) = (transmitted/received word point) N5
(number of other PLCs)
(
s)
Use the following values for N5
N5
CPU type
Systems with only a main base
unit
Systems that include additional
base units
Q02CPU
Q02HCPU, Q06HCPU
Q12HCPU, Q25HCPU
0.54
s
1.3
s
18
Содержание QCPU (Q Mode)
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Страница 450: ...App 59 App 59 MELSEC Q APPENDICES MEMO ...