PA500 - program change of rhythms using external keyboard?

[gmeredith]

I've been getting my head around external MIDI control of a PA500.

I am using a Hammond XK3c keyboard setup as an external controller keyboard. The Hammond has a top keyboard (solo), a lower keyboard (accomp) and bass floor pedals. Each keyboard can send out on a separate MIDI channel. I have the top keyboard set to send out both notes and program changes on channel 1, and the lower one sending on channel 2. This works fine in changing the PA500 sounds set to ch 1, and also the lower keyboard which is set to ch 2 changes sounds in the PA500 that are on CH2.

What I want to do is use the lower Hammond keyboard to change the rhythm styles on the PA500 remotely - basically just using the PA500 as a remote drum rhythm machine. I'll worry about accompaniment instruments and whole styles later, for now I just want to be able to flip through different drum rhythms on the fly using the Hammond program buttons while playing them.

How do I set the PA500 to do this? And what MIDI send channel should I set the Hammond to?

I've done a search here on this but most of the things don't relate to changing rhythms via program change.

Any help would be appreciated, Cheers, graham