You can use the EXE files in the directory \OS2\DRIVERS to detect if one of the common SCSI adapters is installed (common means: supported by OS/2). These files are detection modules used by OS/2 to detect the installed SCSI adapter.
A list of the used detection modules can be found in the file \OS2\INSTALL\SCSI.TBL. . This list is used by the installation program.
Each of the detection modules returns 0 if the SCSI adapter is installed else a value not equal zero (1 or 255).
For additional information about this file see The Guide to OS/2 WARP Device Drivers (sg244627.boo)