The predefined combinations described above have two limitations:
Of course, on the IDL command line, you can manipulate your data however you want, but this is quite cumbersome if you require the same combination of channels regularly. Therefore, as of SM_GUI Version 1.4, custom (user-defined) display combinations have been implemented, which allow to combine the different signals (within one signal type) to be combined almost arbitrarily. Note, however, that this only works if the program runs in a fully licensed IDL session, not in the Virtual Machine.
Custom display combinations are defined in the config file (see Sec. 5.20). For each combination you want to define, add a line like
custom_display "<name>" "<signal type>::<code>"
One example for a valid custom display definition would be
custom_display "sum inner sidet segments (mVolts)" \ "raw counts / mVolts::sidet01+sidet02+sidet03"This has been split into two lines because of limited space on the manual page, but in the real config file you must use one line only (omit the backslash).
You can omit the quotes around <name> if there are no space characters in it. Since there will always be a space in the signal type, you can't omit those ones. You can use single quotes if you want.
Once custom display combinations have been defined in the config file (note that you have to restart SM_GUI or do Extra Re-read Config File for the changes to take effect), they are available as a separate signal type if they are valid for the file loaded (see below). For new scans, they don't become available until the scan is finished.