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UDP-Support for LabWindows/CVI on RT-PXI-System
Andreas4711
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01-17-2006 10:31 AM
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Hi,
I needed to implement an existing communcation protocol on a RT-PXI-System. This communiction just needs a small platform abstraction layer (PAL) which allows simple commands as read/write/open/close communication channel. I decided to write the PAL in CVI and not in Labview, because this would be more complicated to use with the c-program of the communication protocol. I had to use TCP communication, which is really inconvenient for a fast RT-like communication. However i managed to get it to work with ServerTCPRead/Write etc. I call dll-functions of my communication-protocol from Labview, because i need some of the Labview features, as accessing the FPGA cards. It runs, but the performace is really quite bad. It works considerable better by switching to half duplex, which i understand could only be the case if the implementation of the TCP-Stack is somehow strange. With half duplex mode i barely manage to get the desired performance, but i have to use quite big buffer to get a continuous data stream. I am not very comfortable with this and i think this should work better.
So my questions are:
1) Is it really still true, that there is no UDP-API for Labwindows/CVI running on a RT-PXI-Target? Or have i just missed something? I find it quite unbelievable that this really basic feature is not implemented. I do not need any fancy Server/Client-Thread implementation (in fact i really would prefer to use a more standard API similar to Linux/Windows).
2) It seems that only blocking communication (at least waiting 1 ms) is possible. Any chance to change that? I just avoid this blocking by having a seperat communication thread.
3) Are there any hints on how to improve the performace; apart from turning of the buggy full fuplex mode? What is the TCP-Buffer size?
Software: LabWindows/CVI 7.0, Labview 7.1
Hardware: PXI-8187
Regards,
Andy
I needed to implement an existing communcation protocol on a RT-PXI-System. This communiction just needs a small platform abstraction layer (PAL) which allows simple commands as read/write/open/close communication channel. I decided to write the PAL in CVI and not in Labview, because this would be more complicated to use with the c-program of the communication protocol. I had to use TCP communication, which is really inconvenient for a fast RT-like communication. However i managed to get it to work with ServerTCPRead/Write etc. I call dll-functions of my communication-protocol from Labview, because i need some of the Labview features, as accessing the FPGA cards. It runs, but the performace is really quite bad. It works considerable better by switching to half duplex, which i understand could only be the case if the implementation of the TCP-Stack is somehow strange. With half duplex mode i barely manage to get the desired performance, but i have to use quite big buffer to get a continuous data stream. I am not very comfortable with this and i think this should work better.
So my questions are:
1) Is it really still true, that there is no UDP-API for Labwindows/CVI running on a RT-PXI-Target? Or have i just missed something? I find it quite unbelievable that this really basic feature is not implemented. I do not need any fancy Server/Client-Thread implementation (in fact i really would prefer to use a more standard API similar to Linux/Windows).
2) It seems that only blocking communication (at least waiting 1 ms) is possible. Any chance to change that? I just avoid this blocking by having a seperat communication thread.
3) Are there any hints on how to improve the performace; apart from turning of the buggy full fuplex mode? What is the TCP-Buffer size?
Software: LabWindows/CVI 7.0, Labview 7.1
Hardware: PXI-8187
Regards,
Andy
01-17-2006 11:22 AM
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Sorry, I accidently posted that into the wrong forum, should have been LabWindows/CVS. I will repost it there, this thread can be deleted.
