Mitsubishi Q2ACPU User Manual

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12. OVERVIEW OF PROCESSING PERFORMED BY THE QnACPU
(3) Execution time for low-speed execution type program executed in one scan
(a) When operation of all low-speed execution type programs is completed within
one scan and there is surplus time, the subsequent processing varies depending
on the setting status of special relay SM330 and the execution condition for the
low-speed execution type programs.
*1 When the constant scan time is set, the low-speed execution type program is repeatedly
executed for the surplus time of the constant scan.
Accordingly, the execution time of the low-speed execution type program is different at each
scan. If surplus time in constant scan is less than 2ms, the low-speed execution type program
is not executable.
When using a low-speed execution type program, set a proper constant scan time so that
surplus time will be 2ms or longer.
*2 When the low-speed program execution time is set, a low-speed execution type program is
repeatedly executed for the set time duration.
Accordingly, the scan time is different at each scan.
*3 When the constant scan time is set, surplus time after completion of the low-speed END
processing is used as wait time. When the set constant scan time is reached, the scan
execution type program is executed.
Wait time for constant scan
Therefore, the scan time for each scan is constant.
If surplus time in constant scan is less than 2ms, the low-speed execution type program is not
executable. When using a low-speed execution type program, set a proper constant scan
time so that surplus time will be 2ms or longer.
*4 When the low-speed program execution time is set, operation of the scan execution type
program is started ignoring the surplus time after completion of the low-speed END
processing.
Accordingly, the scan time is different at each scan.
• Non-synchronization
method (SM330 = OFF)
: Operation of a low-speed execution type
program is continuously executed within
surplus time.
• Synchronization method
(SM330 = ON)
: Even if there is surplus time, operation of a low-
speed execution type program is not executed
and another operation starts from the next
scan.
Operation method
of low-speed execution
type program
Setting
status of
SM330
Execution condition of low-speed execution type program
Constant scan setting
Low-speed program execution
time setting
Non-synchronization
method
OFF
Re-executes low-speed
execution type program.
*1
Re-executes low-speed
execution type program.
*2
Synchronization method ON
Constant scan wait
time occurred
*3
Starts scan execution type
program operation.
*4
= (Set constant scan time) - (Scan time) - (Low-speed scan time)
= (Set low-speed program execution time) - (Low-speed scan time)
Surplus time in low-speed program execution time

Mitsubishi Q2ACPU Specifications

General

Brand	Mitsubishi
Model	Q2ACPU
Category	Controller
Language	English