How do I log data from multiple serial instruments at the same time?

[tbob]

How is your system configured?  Do you have several instruments, each connected to a different serial port?  How do you go around sending commands to each serial port and then reading from them?  In you vi, you have VISA Write, Read, and Close, but I didn't see any VISA Open.

[johnsold]

I don't think you need to set the timeout each time you call the VI. Do that in the configuration section.

What is your baud rate? How long does the instrument take to respond to a command? Since you read immediately after writing, if the data is not ready, the read VI will wait.

If you put the writes and reads in separate VIs and use Bytes at Port to determine when data is available, you should be able to minimize the impact of multiple reads.

Lynn