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MELSEC-Q
8 MULTITASK PROCESSING
8.2 How to Synchronize the Execution (Event Control)
In the multitask processing, the processing of each program proceeds independently.
Therefore, correct data may not be received, depending on the timing, when the data
needs to be exchanged between programs.
Event control is a method for synchronizing the executions. A program is kept waiting
for a signal (WAIT status), and is allowed to continue its execution when the
appropriate signal (event) is given.
B
B
B
A
A
A
Task A
Task B
(Signal)
You may
start.
In addition to the BASIC programs, a predefined extension relay (EM) in the
communication module can also generate signals for releasing the wait status.
It is possible to perform event control that synchronizes the executions of the BASIC
programs in AD51H-BASIC. In order to achieve this, define events according to the
specific procedures and specify the settings so that event generation is enabled.
Содержание A1SD51S
Страница 183: ...11 13 11 13 MELSEC Q 11 INSTRUCTIONS AND FUNCTIONS RUN Before swap A 0 H924 A 1 H1159 After swap A 0 H1159 A 1 H924 OK...
Страница 331: ...11 161 11 161 MELSEC Q 11 INSTRUCTIONS AND FUNCTIONS REMARK See the CON ON OFF STOP and ZOPEN functions and Section 7 4...
Страница 557: ...11 387 11 387 MELSEC Q 11 INSTRUCTIONS AND FUNCTIONS REMARK See the CHR SPACE and SPC functions...
Страница 629: ...11 459 11 459 MELSEC Q 11 INSTRUCTIONS AND FUNCTIONS REMARK See the ZOPEN ZSEND and ZCNTL instructions and Section 7 3 4...
Страница 645: ...11 475 11 475 MELSEC Q 11 INSTRUCTIONS AND FUNCTIONS REMARK See the ZEVENT ZSIGNAL and DEF ZEVENT instructions...