Visa Read problem from a PIC24's UART port

Thanks for taking the time to read my post.
I am using Labview 8 on Win XP CPU 3.4, 2GB RAM PC.
I am using a microcontroller PIC24 (on the Explorer 16 development board), which I have programmed to acquire an AC singal at a rate of about 4 kHz. The PIC24 has a 10bit ADC and the acquire value is then padded to16bits in total (format: 000000xxxxxxxxxx).
The serial setting for the pic and my Labview program are 115200, 8 data bits, no parity, 1 stop bit.
In order to send the acquired value to my PCs serial port (Remember UART = 8-bits of data only) I divide the 16 bit word into MSB and LSB. I then send the MSB and LSB 8-bit value one after the other.
The total data rate for this communication is about 64kbps.
The problem is that when I run the code I have written in Labview the CPU usage shoot up to 70% and I also see buffer overruns (a non continuous sine wave). If I a time delay in my while loop the buffer overruns increase.
Also if I try and use the ‘bytes at port’ VI the data I get is meaningless.
I would be grateful if someone can look at my code and give me some suggestion as to how I could make the ‘Visa Read’ VI more efficient.
Regards
Alex
Attachments:
Serial Client for PIC24.vi ‏101 KB

Dear all,
I do not know if you have been following my post, but I am still getting buffer overruns (a non continuous sine wave) when using VISA Serial Read.
The only way to avoid this, is by making the VISA Read VI, read 2-bytes at a time (with no time delay in the main while loop). However, when I do this I see the CPU usage shoot up to around 60% (which is something I would expect anyway, as the main while loop is executing as fast as possible).
I have attached the working code below and would appreciate ANY comments BIG or small.
I am still puzzled as to why when I connect the ‘Bytes at Port’ Property Node, the data I get is not correct.
I have gone through the Labview Examples, as well as the LV Basics 1 course examples (which are similar) and I have also looked in the Labview for Everyone / Labview Graphical Programming books.
However, I have found the examples to be far too simple, for what I am trying to achieve.
I am seriously thinking of purchasing the LV Instrument Control Self-Paced Course, but I am not quite certain this would help me much. I have read the Course outline provided by NI, but this did not provide me with more valuable information.
Can anyone that has ‘done’ this course advice me as to whether the material contains info on ‘high’ speed acquisition using VISA Serial Read/Write?
The course is slightly price at a cost of around £240(with academic discount) and as far as I understand the courses examples (might) use two HP instruments (Multimeter and Function Generator) and a Tektronix oscilloscope, all of which I am not in direct contact with.
Regards
Alex
Attachments:
Serial Client PIC24-Serial - Read 2-bytes.vi ‏42 KB

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