Answer:
To modify an existing element, you have to get the interface to the corresponding element, in this case on an example of a member:
Dim iModel As RSTAB8.model Set iModel = GetObject(, "RSTAB8.Model") iModel.GetApplication.LockLicense Dim iModData As IModelData Set iModData = iModel.GetModelData Dim iMem As RSTAB8.IMember Set iMem = iModData.GetMember(1, AtNo)Use this code to get the interface to Member 1, which should already be created. Then, you can use the .GetData() method of the interface to get the member data.
If you want to modify data (such as the member rotation in this case), you can transfer them to the program afterwards within a Prepare-/FinishModification block using the .SetData() method:
Dim mem As RSTAB8.Member mem = iMem.GetData mem.Rotation.Angle = 0.5 mem.Rotation.Type = RSTAB8.Angle iModData.PrepareModification iMem.SetData mem iModData.FinishModification
