Yamaha DTXpress/DTXplorer/DTXtreme

I am a novice user. I just bought a new Yamaha dtxplorer. It seems the 
hi hat foot pedal is able to generate 2 types of sounds. One is the 
normal sound you expect and it is easy to do by briefly lifting the 
pedal. The other is a splash sound similar to regular cymbal. I think 
it is supposed to be done by rapidly pushing the pedal down. I have 
found that is extremely difficult to do the splash consistently. Any 
advice? 

Sorry this is dtxplorer instead of dtxpress.