Mitsubishi MELSEC-Q Series User Manual page 16

Precautions for programming
A
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(1) Restrictions on bus interface functions and MELSEC data link functions
(a) Endian format (Memory layout)
The C Controller module uses the endian format (memory layout) of little endian.
Perform programming of the user program in little endian.
(The compiler is set in little endian by selecting "SH7750gnule" in "A toolchain"
when creating a project on Tornado.)
( Section 10.2.3)
(b) User program execution
Execute the user program by starting a task from a script file.
( Section 10.2.8)
The system may malfunction if the user program is executed without a task being
started.
(c) Execution task priority
Set the priority of the task that executes the user program as described below.
1) When FTP access is not made during user program execution
Set the priority of the user program task to 100 or higher (100 to 255).
If the priority is set to 0 to 99, the system may not operate properly.
2) When FTP access is made during user program execution
The actual FTP processing (task) of the C Controller module is performed at
the priority of 200.
When making FTP access during user program execution, perform
programming as described below.
• Set the priority of the user program task to 201 to 255.
• When setting the priority of the user program task to 100 to 200, insert wait
processing (such as taskDelay) in the user program to enable the actual FTP
processing.
(d) Ethernet communications from user program
The port numbers 20756, 21012, and 21268 are not applicable.
(e) File writing from user program
Do not write files to the standard ROM.
Write data to the files such as CompactFlash card and network device (FTP/NFS/
netDrv driver, etc.).
For details of network device, refer to the manual for VxWorks.
(f) When operation status changes from RUN to STOP/PAUSE
When the operation status of the C Controller module changes from RUN to
STOP/PAUSE, the user program task does not stop.
Use the QBF_ReadStatusEx function when changing the user program
processing based on the operation status of the C Controller module.