Top Ten SCPI Programming Tips for Signal Generators - Rohde ...

Miscellaneous Tips
10.4 Code Debugging
If you need to debug your code, it is helpful to insert error queries at multiple positions
in the code to quickly find the source of error (e.g. a wrongly spelled command). Also,
send *OPC after each command – except for very time-consuming operations – and
check if a “1” is returned (e.g. display the “1” on the screen for visual control).
You can also use dedicated tools for debugging. For example, special debug features
of your programming environment allow you to step through the individual code lines
manually. These debugging tools can be used to identify SCPI commands in the code
that produce an error on the instrument (e.g. because a level value that is too high has
been sent to the instrument). Another debugging tool is the NI Spy tool from National
Instruments; it allows you to see what information is actually sent over the VISA
interface. For example, this tool can be used to check if the SCPI command is indeed
sent to the right instrument or accidentally to another instrument of the test setup. Also,
codes often contain SCPI commands that contain values which are not predefined but
are calculated during the run. These values are included in the SCPI command by
means of e.g. %f in C codes or variables in MATLAB codes. Using NI Spy, you can
check if the resulting SCPI command sent to the instrument is indeed what it is
supposed to be or if, for example, spaces are missing or the calculated value is wrong
(e.g. wrong dimension: Hz GHz).
1GP79_1E Rohde & Schwarz Top Ten SCPI Programming Tips for Signal Generators 35