As you might know from this post https://forums.autodesk.com/t5/robot-structural-analysis-forum/diaphragm-problem-to-be-corrected/m-p...

There are several issues with diaphragms in Robot: 

1. The master node for the diaphragm is located in the geometric center of the slab. The diaphragm master node should be in the projected center of gravity of the story on the floor slab level.
2. If in the model we have more than one-floor slab at the same level, the diaphragm will be created for each slab individually. The diaphragm should be one for each level.
3. It is not possible to assign loads to the master node and get results (eigenvectors etc.). Also, this node is not considered in FE mesh. The master node should be accessible as a common regular node in Robot.

The Diaphragmer is the solution to the above-mentioned issues.

Microsoft Excel 2013 and later is required to run this tool. VBA macros shall be enabled

Note: This app uses a custom installer (and not the standard App Store installer).