Hi Budi,
Regarding CAD integration with RE-FX there a few solutions available.
1. FM Insight (http://www.fminsap.com/fm-insight/sap-cad-integration/). Contact Mr. Elwin Herrenbout (EHerrebout@npqmail.com), tel: +31(0)30 659 7411
2. Cideon (http://www.cideon.de/site/us/en/cideon-us/real-estate-facility-management-mit-sap/index.php).
Regards, Andre