The term "SAP System " is used here to refer to the of the subcomponent "SAP_BASIS" of your SAP System.
1. SAP GUI higher than or the same as the SAP System
It is possible to connect newer versions of SAP GUI to an older SAP System, and SAP explicitely recommends this, because the SAP GUIs are downward-compatible. For example it is possible to connect to an R/3 system of 3.1I with SAP GUI 7.30. Please note that SAP only guarantees compatibility of SAP GUI to s of SAP Software which are still being maintained by SAP.
2. SAP GUI lower than the SAP System
This status is not generally supported due to the fact that changes in the interface between Application Server and SAP GUI may be required in a new SAP System . Sometimes new features required by a new SAP System may also only become available in a new SAP GUI . If such a case occurs SAP will publish along with the SAP System a suitable SAP GUI version.
Also new SAP GUI functions not required by the SAP System available in new SAP GUI are usually not "downported" to earlier, so an upgrade of SAP GUI may be desirable due to new features in a newer .
Due to the stabilization of the interfaces between SAP GUI and SAP Application Server it is possible to use SAP GUI for Windows 7.30 to connect against all currently supported SAP Systems (including 7.40).
Additional Information:
You can use different versions / patchlevels of SAP GUI to connect to a single SAP System in parallel. Using different SAP GUI versions for connecting to an SAP system does not cause any harm to the system. Please note that only a single version of SAP GUI for Windows can be installed on a client computer.
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