Programming Flow; Precautions - Mitsubishi Electric MELSEC Q Series User Manual

21.3

Programming Flow

The following shows the user program flow that involves these functions.
21.4

Precautions

(1) Opening and closing processing of the bus
Execute the opening and closing (QBF_Open function/QBF_Close function) processing of the bus at the start
(task startup) and end (task end) of each user program.
Repeating opening and closing for each communication impairs communication performance.
(2) Execution of functions in multiple tasks
• Execute the bus opening processing in (1) for each task. A path acquired by the QBF_Open function cannot
be shared among tasks.
• When the MELSEC data link function are requested simultaneously in multiple tasks, one of the task starts
its processing and the other tasks will have to wait until the processing is complete.
(3) Function execution in remote STOP or remote PAUSE status
An error will occur if the following functions are executed with the C Controller module in the operation status of
remote STOP or remote PAUSE.
• Output (Y) (QBF_Y_Out_BitEx function, QBF_Y_Out_WordEx function)
• Buffer memory writing (QBF_ToBuf function)
However, turning ON/OFF the output (Y) and writing to buffer memory from the [Online]  [Device monitor] of
Setting/monitoring tools for the C Controller module are allowed.
360
Task start
Open a bus.(QBF_Open)
Use the bus interface function to control the module(s).
End the task?
Yes
Close the bus. (QBF_Close)
Task completion
No