You wouldn't happen to be specifying a byte count to read or setting read termination when a specific character is read would you? If you are, if you don't have the right number of bytes in the serial buffer or if the termination character is not seen, then VISA read will wait for the time specifed by the VISA timeout value. To fix the first problem, use the VISA Bytes at Serial Port function to determine how many bytes to read. In the second case, use a VISA property node to set Message Based Settings:Termination Character Enable to false and Serial Settings:Serial End Mode for Reads to none.
