National instruments usb-232 driver download - remarkable, this
3. VISA and VISA Tools
*Note4 - Termination Character '\n'
'\n' is a Linefeed (LF) termination character, hexadecimally represented as 0x0A. It serves as message termination character.
In case of RawSocket and Serial connection, for VISA Write operations you always have to terminate strings with the LF character, because that is the only way to tell the instrument that message has ended. To recognise the end of the response in VISA Read operations, you need to set the VISA attributes VI_ATTR_TERMCHAR_EN to TRUE and VI_ATTR_TERMCHAR to 0x0A. Otherwise, although VISA Read receives correct response, it finishes with timeout error since it still expects more bytes to arrive.
Some instruments require the LF regardless of the connection type. In any case, sending the message with the LF at the end is the most universal and always works properly.
According the SCPI standard, instruments must terminate responses with LF. In our example above, notice the LF at the end of the identification string response in the NI Visa Test Panel. RsVisaTester does not display white characters, but you can see them in the RsVisaTraceTool log.
-
-