All, Thanks for your help. Issue is solved. the file is needed was not on the support website anymore, but because the Windows file was available, that file was available from payloud folder.
All,  At this moment I'm trying to update the firmware of 8 iDRAC interface via iDRAC webinterface and via CMC interface, unfortunately it doesn't work. On our M600 we are running Xenserver. From DELL Enterprise support I get .exe files to upload, but then I get an error while updating firmware that image is not correct to update firmware.  My simple question is where can I find/download the correct file to update firmware of iDRAC via webinterface.  Hopefully I get soon an answer.  Thanks in advance!
Updating iDRAC firmware of M600