The Standard Text Debugger (sdb) command line tool is used to observe variables on SIMATIC 1500 PLCs. It is capable to observe also local, global, static and temp variables.
The debugger requires a program built with the STC option '--debug'. The program must be downloaded to a SIMATIC 1500 using either the SIMATIC AX sld or, in the case of the TIAX workflow, the TIA Portal.