VISA Read gets incorrect data from serial connection

Question

I am having difficulty using the VISA functions in LabVIEW to read data from a virtual COM port. Data is being sent from a serial to USB chip via a USB connection using OpenSDA drivers. I have a python program written to read from this chip as well, and it never has an issue. However, when trying to achieve the same read in LabVIEW I am running into the problem of getting incorrect data in the read buffer using the VISA Read function.
I have a VISA Configure Serial Port function set up with a control to select the COM port that the device is plugged into. Baud rate is default at 9600. Termination char of my data is a newline, which is also default. Enable termination char is set to true. A VISA Open function follows this configuration, and then feeds the VISA Resource Name Out into a while loop where a VISA Read function displays the data in read buffer. Byte count for the VISA Read is set to 20 so I can read more of the erroneous datat, however actual data will only be 6-12 bytes. The while loop has a wait function, and no matter how much I slow down the readings I still get incorrect data (I have tried 20ms thru 1000ms). 
The data I expect to receive in the read buffer from VISA Read is in the form of "0-255,0-255,0-255\n", like the following:
51,93,31\n
or
51,193,128\n
And occasionally I receive this data correctly, however I intermittently (sometimes every couple reads, sometimes a couple times in a row) get incorrect readings like this:
51,1\n
51,193739\n
\n
51,1933,191\n
51,,193,196\n
51,1933,252 
51,203,116203,186\n
Where it seems like the read data is truncated, missing characters, or has additional characters. Looking at these values, however, it seems like the read was done incorrectly because the bytes seem partially correct (51 is the first number even in incorrect reads).
I have search but haven't found a similar issue and I am not sure what to try from here on. Any help is appreciated. Thanks!
Attachments:
Serial_Read_debugging.vi ‏13 KB

Answer 1

The first thing is that none of the error clusters are connected so you could be getting errors that you are not seeing. Are you sure about the comm parameters? Finally, I have never had a lot of luck looking for termination characters. You might want to just capture data and append each read into one long string just to see if you are still seeing this strangeness.
What sort of device is returning the data? How often does it spit out the data? How much distance is there between it and your computer? Can you configure it append something like a checksum or crc to the data?
Mike...
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