SIMADYN D is in phase out state and should not be used for new projects.
Actual products and similar to SIMADYN D are T400 (for Masterdrives) FM458 (for S7-400) and SIMATIC TDC.
Older SIMADYN D sations were programmed with STRUC L or STRUC G.
The files are CFP, CMP, UFP, UMP, OFP, OMP.
Newer ones used STEP 7, CFC and D7-SYS.
The file is a Step7 Archive (ARJ or ZIP)
It would help me a lot if you can say which SIMADYN D Processor you have (eg. PM16, PM5, PT16, PT31 etc) to replace and what you plan to use instead of it.
mfG / Best Regards