problem with sampling using LabVIEW through RS232 communication

[applehan]

I am doing a data aquisition system getting data from Serial port through RS232.In the while loop, when receiving a 'W' command, LabVIEW reads stream values continuous from the 8 analogue channels and display on the waveform chart. Read 'W' command again, and get 8 channels signals again.
I use a signal generator to give sine wave to one channel to test it, but it cannot display the sine wave properly on the waveform chart. Can you help me with this, thanks!

[Ray.R]

I am trying to correctly understand what you are doing. Are you generating a sine wave which is read by a device which has some osrt of A/D converter? This device then transmits the sampled waveform through the RS-232 port when it receives the command "W"?

If so.. Is there a way for you to verify that what is sampled and stored on the device is the same as what it transmitted through the serial port? Are you expecting a certain number of samples? If so, can you verify the number of readings that were transferred? What I am getting at is maybe the problem is not at the serial port.

Let's consider that it might be. Can you visually see the data obtained? Do you save it to file or can you display it using an indicator or table? Look for strange c
haracters. If there are some, then look at your port settings.

Is the data acquisition system using an "off the shelf" board or device or is it home-made?

Sorry to answer with so many questions.

JLV