Oly_R,  The adapter you would need is the LSI-2032. As found on page 9 of the R415 technical guide - [URL] The LSI2032 part number is NU947. Let me know if this answers your question.
I was looking through the available upgrades for the R415 to find a scsi adapter card. I don't see one listed but was hoping someone could point me to a compatible card. We have to connect to  scsi tape drives.
Poweredge R415 - External SCSI Tape drive?