As of R/3 Release 3.0C, you can use the full functionality of the ABAP debugger when developing an application using RFC.
Depending on the structure of the program to debug, you can use different techniques:
Another way of doing this is to define an entry in the saprfc.in’ file which includes all necessary parameters and the RFC-specific parameter RFC_TRACE in the saprfc.in’ file. An RFC client program can then issue the RfcOpen call with the mode RFC_MODE_PARAMETER and a destination pointed to the defined entry. See The SAPRFC.INI File for more details.
In R/3 Release 3.0C, this functionality is only supported for Windows NT, Windows 95 and all supported UNIX platforms (Motif). In particular, this functionality is not available for 16-bit Windows environments (Windows 3.x, as well as the 16-bit subsystems of Windows NT and Windows 95).
Moreover, you have to install a SAPGUI program on your system which must be of Release 3.0C or later.
Under Windows NT and Windows 95, the SAPGUI program and its DLLs and auxiliary programs can be installed anywhere. However, you must have started ‘SAPGUI’ once before you can use it via RFC, because the program must register itself in the Windows registry.
Under R/3-based UNIX, the SAPGUI program must be installed on the normal SAP path /usr/sap/<system name>/SYS/exe/run.