Debugging RFC function module from ECC to CRM

Question

Hi All,
My requirement is to debug an RFC function module present in CRM(7.0) system from ECC(6.0) system. A report program in ECC will call CRM custom FM. I found many posts in SDN with the same issue and tried to implement suggestions provided there. But I couldn't succeed. The approach I followed is:
I logged in to ECC report program and kept an external breakpoint just before the function module call.
I logged in to CRM system, opened the function module and kept an external breakpoint there.
In both the systems I provided the dialogue userid( id through which I log in to SAPGUI) in the system->settings->debugging option.
In CRM I activated the external break point in  transaction SRDEBUG.
Now when I execute the report program in ECC, control stops at the breakpoint. If I press F5 at the function call, control is not going to the external break point set in the CRM FM. I am getting output of FM directly.
I tried with different settings like turning on the check box for IP matching and session breakpoint active immediate, switching to classic debugger etc. I also tried to provide the RFC user id instead of dialogue user but system throws exception saying only dialogue userids are allowed. I found that by inserting an infinite loop statement, control goes inside the RFC CRM FM but I prefer not to change the code.
Please let me know if I missed anything.
Thanks and Regards,
Naren

Answer 1

Hi,
Debug RFC calls
When an RFC function module is called it is usually not possible to debug the call, using the below techniques we can achieve the same. For this example we are calling an RFC enabled FM in ECC system from CRM system.
Scenario 1: Calling a custom RFC FM
STEP 1: Add an infinite loop in the remote custom Function Module (adding a u201CDO. ENDDO.u201D statement at the start of the FM would be enough).
STEP 2: Execute your program in the CRM system. The execution stops at the RFC call, because of the infinite loop.
STEP 3: Now login to the ECC system and go to transaction SM51 select the process which is executing the RFC and navigate to the menu: u201CProgram/Session->Program->Debuggingu201D this triggers the debugger session in a separate window.
Scenario 2: Calling a Standard RFC FM
When we are debugging a standard program we cannot add the infinite loop, hence we cannot go to SM51 and debug the work process. The RFC destination for the ECC system has a User specified, the RFC function module gets executed using this users credentials. Usually the basis team set up the RFC user as non Dialog user, this does not allow debugging. Contact your Basis team and get this changed to a dialog user enabling you to debug RFC function calls via the normal debugger.
Note: User name configured in the RFC destination (transaction SM59) 
Note: User type for the RFC User (transaction SU01D)
Hope this will be helpful..