Are you sure that your optical drives are SCSI? Because they are the only type that dll looks for. I tried it on my system (which uses IDE drives) and I get no errors, but no information (as you might expect). 

#! perl -slw
use strict;
use Win32::API::Prototype;

ApiLink(
    'DiscIdCalcDLL', q[ int GetCdRomDrives( LPVOID p ) ],
) or die $^E;

my $struc = chr(0) x ( 4 + 1036*3 );

GetCdRomDrives( $struc ) or die $^E;

print "'$_'" for unpack 'v( VVV (a256)4 )3', $struc;

__END__
c:\test>DiskId.pl
'0'
'0'
'0'
'0'
'
'
'
'
'0'
'0'
'0'
'
'
'
'
'0'
'0'
'0'
'
'
'
'

[download]

However, you can query most everything about your system using DBD-WMI (though working out the right classnames can be a pain): 

#! perl -slw
use strict;
use DBI;

my $dbh = DBI->connect('dbi:WMI:');

my $sth = $dbh->prepare(<<WQL);
SELECT  Caption, Name, Drive FROM  Win32_CDROMDrive
WQL

$sth->execute();
while( my @row = $sth->fetchrow ) {
    printf "Caption:  %25s Name:%30s Drive; %s\n", @row;
}

__END__
c:\test>junk
Caption:  HL-DT-ST CD-ROM GCR-8481B Name:  HL-DT-ST CD-ROM GCR-8481B D
+rive; R:
Caption:   LITE-ON DVDRW SOHW-1693S Name:   LITE-ON DVDRW SOHW-1693S D
+rive; D:

[download]

There are a whole bunch of other fields besides the 3 I've queried. They include: 

Availability  
Capabilities  
CapabilityDescriptions  
Caption                    
CompressionMethod  
ConfigManagerErrorCode  
ConfigManagerUserConfig  
CreationClassName  
DefaultBlockSize  
Description   
DeviceID                                                              
+       
Drive  
DriveIntegrity  
ErrorCleared  
ErrorDescription  
ErrorMethodology  
FileSystemFlags  
FileSystemFlagsEx  
Id  
InstallDate  
LastErrorCode  
Manufacturer              
MaxBlockSize  
MaximumComponentLength  
MaxMediaSize  
MediaLoaded  
MediaType  
MfrAssignedRevisionLevel  
MinBlockSize  
Name                       
NeedsCleaning  
NumberOfMediaSupported  
PNPDeviceID                                                           
+       
PowerManagementCapabilities  
PowerManagementSupported  
RevisionLevel  
SCSIBus  
SCSILogicalUnit  
SCSIPort  
SCSITargetId  
Size        
Status  
StatusInfo  
SystemCreationClassName  
SystemName  
TransferRate  
VolumeName       
VolumeSerialNumber

[download]
Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
"Science is about questioning the status quo. Questioning authority".
In the absence of evidence, opinion is indistinguishable from prejudice.
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In reply to Re: Win32::API arguments by BrowserUk
in thread Win32::API arguments by VMat

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