Receive 9 bytes to the array, and test for the "Box" code after receiving the data.
Maybe something like this...
Code:
HSERIN [wait($7E),STR INP\9]

SELECT CASE INP(0)
    CASE $80
         ; The data for Box $80 is in INP(1 thru 8)

    CASE $81
         ; The data is for Box $81

    CASE $82
         ; The data is for Box $82

END SELECT