serialport = Val(InputBox("Select ComPort 1 or 2?", "ComPort selection", 1)) 
Loop Until serialport = 1 Or serialport = 2

There is absolutely no need whatsoever to artificially restrict your code to only COM1 or COM2 like this.

This was one of the many annoying features of early hypoterminals - it only ever went up to COM4

[rant]
When you have many serial ports on your PC (eg, USB-RS232 adaptors; TCP/IP-RS232 adaptors; multiport serial cards, etc) it is very annoying to find software that is too lazy to determine the actual PC capabilities, and just blindly restricts you to COM1 or COM2 (or even COM3 and COM4).

Well-written Windows software will present the user with a full list of the serial ports actually available on the system.
[/rant]