No command prompt needed for Makehex. Simply drag your .irp text file with its proper modifications that you require onto the makehex application icon and the rest is automatic. John was not interested in creating a GUI for the application.

Hello All, Thanks for posting all the info. Its a little over Whelming. I am really confused with the Marantz spreadsheet. All the codes are the same. Example Power On: 16.12.01. I am trying to figure out the chart. Is there a unique code for each device? I have a SR5002 that i am working on. What does the exact POWER ON command look like for the SR5002? Can someone explain. Thanks in advance.

I am not sure what you mean... the codes are not all the same the last number will be the unique function number.

Marantz Power On 16 12 01 is an RC5x code.
Device: 16.12
Function: 01

Makehex generates:
0000 0073 0000 0011 0020 0020 0040 0040 0040 0020 0020 0020 0020 0020 0020 00A0 0020 0020 0020 0040 0020 0020 0040 0020 0020 0020 0020 0020 0020 0020 0020 0020 0020 0020 0020 0040 0020 0AA4

The process is fairly simple: -open the RC5x.irp file, -edit the first two lines to match (as the above example), -save, -drag and drop the .irp file onto the Makehex.exe, -open the resulting RC5x.hex file and you will see your generated code.

Marantz codes from the spreadsheet are basically in two forms, RC5 and RC5x.
The 3-byte codes (ie. 16 12 01) are RC5x, where the first two bytes (separated by a decimal) are the Device code, and the third byte is the Function code.
The 2-byte codes are RC5 codes, and are simply a Device code and a Function code. Example is the Power Toggle 16 12

A more thorough explanation can be found here:
[Link: remotecentral.com]

you guys are great. the new rs232 library fixed my Denon 4308 issues immediately. these codes actually work for Denon, unlike the stock library.

thanks so much guys!