One method that I have used to work with Serial Port devices, in the old days, is to write to the file called "COM1:" or whichever comm port you have used.
However, I haven't tried this in VBA yet.
Now I have:
private function opencom1() as Long
dim a%
a% = freefile
use open "COM1:" for output as a%
opencom1 = a%
end function
this should return the file number for your "opened" com1:
You willneed to know what bytes/bits you need to send to open the drawer.
Hope it helps.
Deefa.