Hello, You mention that you send a string to the microprocessor that tells it how many bytes to send. Instead of requesting 512 bytes, try reading 10 times and only requesting about 50 bytes at a time.
If that doesn=92t help, try directly communicating with your microprocessor through HyperTerminal. If you are not on a Windows system, please let me know. Also, if you are using an NI serial board instead of your computer=92s serial port, let me know. <ol><li>In Windows XP, go to Start, Programs, Accessories, Communications, and select HyperTerminal.</li> <li>Enter a name for the connection and click OK.</li> <li>In the next pop-up dialog, choose the COM port you are using to communicate with your device and click OK.</li> <li>In the final pop-up dialog, set the communication settings for communicating with your device.</li> <li>Type the same commands you sent through LabVIEW and observe if you can receive the first 54 bytes you mention. Also observe if data is returned from your 512 byte request or if HyperTerminal just waits.</li></ol> If you do not receive the 512 byte request through HyperTerminal, your microprocessor is unable to communicate with your computer at a low level. LabVIEW uses the same Windows DLLs as HyperTerminal for serial communication. Double check the instrument user manual for any additional information that may be necessary to communicate. Please let me know the results from the above test in HyperTerminal. We can then proceed from there. Grant M. National Instruments
