This thread discusses various PC applications that can add new functionality to Yamaha receivers via an RS-232 connection. (Note that they won't work on the RX-V3900 or RX-Z7 because these models use a different RS-232 protocol.)
This may be of interest to anyone who doesn't like the graphical volume display on recent models and wants to see larger numbers displayed on the front panel. It also allows you to display various extra information such as the current signal info or time of day on the front panel.
The idea of this application is not to control the receiver directly (i.e. you don't have to sit with a laptop while watching a movie!), but instead the PC application will modify the behaviour of the regular remote control, to add new features you didn't have before. (Note that it requires an active RS-232 connection at all times to the application running on the PC in order to work. When you break this connection you lose the new functionality.)
The latest version of VolumeControl can be downloaded here.
Screenshots and more information are here.
Note that if you have an RX-V1800 or HTR-6190 you can get a better fix for the volume display by installing new firmware.
Unfortunately VolumeControl won't work on the RX-V1700/2700.
This program's main purpose is to allow you to make manual changes to the parametric equalizer on models that don't normally allow it (the RX-V1700/1800/1900). However, it also works on other models and is quite useful even without an RS-232 connection as a way to visualize how the PEQ parameters (especially Q) affect the shape of the filters.
The latest version of PEQedit can be downloaded here.
Screenshots are here, and in the following post.
There are many other things that could potentially be done. For instance it should be possible to implement something like THX Loudness Plus (similar to Audyssey Dynamic EQ), that automatically changes the tonal balance and surround levels as the volume is lowered.
If anyone is interested in the Yamaha RS-232 protocol, download this.
Within that ZIP file the most useful documents are for the Vx700 (they are more complete than those for the Vx800). In RX-Vx700_RS232C_Standard.pdf, the first page explains what kind of cable is needed (it's a Null Modem cable where pins 2/3 and 7/8 are reversed w.r.t. a normal RS-232 cable).
If your computer doesn't have a serial port then there are plenty of USB to serial adapters available that will give you ability to connect to your receiver's RS-232 port.
Edited by kriktsemaj99 - 8/16/12 at 2:47pm