Just bought a Digitech RP1000 to play with in our worship band. The patch assignment is a breeze making it a great effects pedalboard for my needs. I'm setting up a tremolo patch as one of my presets but can't figure out how to assign the expression pedal to adjust the rate while playing. My old GNX3 could do it and my hopes is that the RP1000 can as well. Any helpful advise is greatly appreciated.