FTDI RS232 data skipping

[tommytommy]

Hello,

I am using the FDTI software example 1 for Labview downloaded from FTDI page

http://www.ftdichip.com/Support/SoftwareExamples/CodeExamples/LabVIEW.htm

to read from an RS232 interface. I downloaded and installed the dll to configure my device on a virtual COM port and I am sending a sawtooth signal from the FDTI chip to the PC via USB.  I modified the FTDI example adding a scope and writing the data to text file.

The settings for reading are

Baudrate = 115200

Word length = 8 bit

Stop bit = 1

Parity = 0

Flow control = None

Everything seems to work in the Continuous Mode, except that I notice  data skipping every 1315 samples, or every 2 or 3 multiples of 1315 samples.

And it is diffult to figure out how many data I am loosing.

Can you suggest what it is going wrong?

I am sure about the realibility of my input signal, and I didn't touch the example file enough to create such an error.

Thanks

[Coq_Rouge]

If the device show up as a virtual comport in windows. You can use the Labview serial port VIs. Much more simple.

[tommytommy]

Exactly! Sorry, I wasn't clear before:

I configure my device as a Serial Port Device in Labview.

If I check from Measurement & Automation Explorer I can see my device on COM4.

Btw, I am using labview 2011. And still I gor data skipping. any further suggestion?

[Coq_Rouge]

Can you post your code, as VI or LLB. Or at least the part as code that do serial setup and cummonication

[tommytommy]

tnx!

this  the only file I modified is "Write-Read Byte Array Demo.vi"

All the rest is like on the FDTI webpage. I get the error when I run in continous mode.

[Coq_Rouge]

First I think you should use standard Labview serial port VIs. Not the VIs you are using. You problem is also related to using the continuous run button. This is only for debugging. The way you are running things. You will on iteration open/clear/close the serial port system. Hence the missing data. The correct thing is to open/configure once. Then in a loop do the reading. After you are done you close down the use of the serial port.

[tommytommy]

Hi again,

thank you very much for your last hint. It is now working with a loop regarding only the buffer reading section, so that I close the device only once I get out of the reading step, pressing STOP.

I didn't get why should I use the standard serial port, since with VI the program works fine. Which kind of problems could I encounter in the future? Is it a matter of stability?

Thanks again!