@ Iain, Adrian and John
If you guys have been thinking that your responses did not help very much or that I was not taking them on board - think again!
Your responses (and the absence of any other responses) prodded me into "thinking outside the box" and as a result of some invaluable collaboration by fellow-Hauptwerkian Nick Nelson, who very graciously took the time to experiment and come up with an alternative way of programming his MIDIMega8e encoder (
http://forum.hauptwerk.com/viewtopic.php?f=15&t=12849&p=94757&hilit=+encoder#p94757 ), we now have a solution that meets all the requirements.
Basically Nick produced an encoder that sends only
note-on messages (for MIDI note numbers 00-31) when the rocker tabs' "STOP ON" switches are closed, but no message when the switches are released and open again; and that sends only
note-off messages (again for MIDI note numbers 00-31 on the same MIDI channel) when the rocker tabs' "STOP OFF" switches are closed, but no message when they open again.
Consequently, when Hauptwerk is configured to send matching MIDI-out, these messages can be understood by the MIDI decoder that drives the stop tab indicator LEDs and that is programmed to respond to note-on/offs for MIDI note numbers 00-32.
Hauptwerk readily auto-detects the stop switches, and the LEDs are automatically catered for with no need for separate manual intervention (which would have been necessary if we had settled for letting the switches generate program change messages).
The upshot of all this is that a c2002 vintage Viscount Concerto III console that was physically in excellent shape but destined for the tip because it had been pronounced "dead" electronically, has been given a new lease of life as a fully-functional dedicated Hauptwerk console. And its owner will very shortly be joining the ranks of the Hauptwerk community.
Regards
Graham