timeout operation serial interface

[timeout operation]

I am interfacing instrument simulator using serial cable rs232.whether i use VISA  or I/O ASSISTANT, "timeout expired before operation completed" ERROR  is appearing.I have downloaded some vis from ni also,BUT the same error is showing up.

The write vi is where the error occurs.

[Dennis_Knutson]

It's pretty unusual for a timeout error on a write. Do you have handshaking enabled?

A timeout on a read is common and can have numerous causes. You might be sending the incorrect command, you might be sending correct command but not terminated correctly, you might have a mismatch in com settings, you might be using the incorrect serial cable.

Before trying any LabVIEW code, debug your serial writes and reads with a program like Hyperterminal.