Mitsubishi Electric MELSEC Q Series User Manual page 342

(8) Execution type priority
Set the priority of a task for executing the FTP user program as described below.
(a) When access is not made via FTP during user program execution
Set the priority of the user program task to 100 or more (100 to 255).
If the priority is set within 0 to 99, the system may not operate properly.
(b) When access is made via FTP during user program execution
The actual FTP processing (task) of the C Controller module is performed at the priority of 200.
When accessing via FTP during executing a user program, perform programming as described below.
• Set the priority of the user program task within 201 to 255.
• When setting the priority of the user program task within 100 to 200, insert a wait processing (such as
taskDalay) in the user program to let the actual FTP processing operate.
(9) To communicate with a target device by Ethernet communication
Check the port number being used in the C Controller module by using the VxWorks standard "netstat" command.
Do not use any port number that has already been used. Normal communication may not be available if used.
Use the Telnet tool to execute the "netstat".
[Example] When the Telnet tool is used
Command
execution
(10)Processing in case there is no response from the function
There may be no response from the function if an error ("MAIN CPU DOWN") occurs in the C Controller module.
Design a user program taking into account the possibility that there is not response from the function.
The error occurrence status can be confirmed by using the C Controller module dedicated function
(CCPU_GetErrInfo).
(11)Fragmentation of memory
When the memory is allocated and free frequently, the system may not operate properly because of the fragment
of the memory.
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Port numbers being used in a C
Controller module.