well you beter get the book as michael suggest,and a quick answer for your vb,
with mscomm1
.commport=1
.settings="9600,n,8,1"
.inputmode=cominputmodebinary
.Rthreshold=27
.inputlen=27'**
end with
and then
a=mscomm1.input' a =27bytes data in binary
** will read 27bytes/times from input buffer
adds this to your vb program,remodify value * and **
to meet your appplcation need
have fun
regards