Lots of progress. Now that I can send commands to the receiver, I am populating the template. The only glitch has to do with the MUTE command. The protocol in the manuals that I have, for the 2310 and 3312, both provide discrete commands for this function, that is, separate commands for on and off. The device template however is built for a toggle command. This is consistent with button on the remote, and I also have a pronto code for this function. I see four solutions:
1: Change the template to accommodate discrete RS-232 commands, though this does not seem possible with the command options in WebAdmin.
2. Find a way to send the pronto code over RS-232.
3. Find an RS232 toggle command for mute that is not in the manuals that I have.
4. Embed an if statement in the ruby code for the command that queries the mute status using <$"MU?\n"$> and then sends the correct discrete command.
If anyone has a Denon receiver working with RS-232 I would be interested to know what you have done for MUTE.