I am writing Excel VBA code for serial I/O, with Windows XP and kernel32, using the code example from http://dev.emcelettronica.com/serial-port-communication-excel-vba
This works fine for COM1 thru COM4. No problems. But when I attempt to address any port number greater than COM4, the "CommOpen" function returns a lngStatus value of 9, which I take to mean "invalid port number".
Near the bottom of the same page, someone says that by changing the root of the port name from "COM" to "\\.\COM" you can use up to COM256. But I can't make this work.
Has anyone here made it work?