How can i know the data that labview takes when calls visa read?????????????

[KURIK]

First sorry for my english!

I have a program in wich i read data trough USB(in bulk mode) from a FIFO(from a microprocesor) . I don´t know if when i do a visa read and the program that is running in my microprocessor is waiting for the FIFO full, what data catch the visa read?, because labview don´t wait, always take data when visa read is call!!

THANKS THANKS......

[chilly_charly]

A read operation just retrieves the bytes that are available on the serial port. Means that these bytes are there because they have already been sent by the connected device. They may be remains from a previous communication.

Your protocol should ensure that

1/ the serial buffer is empty before your start your communication session.

2/ you read either a specified number of bytes, or all the incoming bytes, using a timeout in case of failure

3/ you leave things clean after communication (empty buffer, close port...).

Try to be e more specific if you need further help.