If you want to do it digit by digit you could do something like this

In a 'normal' module:

'***********************************************
Function hextobin(byval hexa as string)

Select Case hexa

Case "0": hextobin = "0000"
Case "1": hextobin = "0001"
Case "2": hextobin = "0010"
Case "3": hextobin = "0011"
'continue until last hexa digit....
'
'
case "F": hextobin = "1111"
End Select

End function

'***********************************************
"Aimran" escribió en el mensaje
...