I just got a HX Effects (firmware 3.71) and was excited to use the Ext Amp jack to control the Vibrato and Reverb effects of my Fender Deluxe Reverb. The amp uses a standard Fender 1/4" TRS dual footswitch to control the Vibrato and Reverb, and the footswitch included with the amp works fine.
I actually have two Deluxe Reverbs, so I was hoping to get this going on both amps, one from each jack! However for the benefit of the first test, I tried a single amp, but had no luck!
I set both pedal jacks to Amp mode in Global Settings > Prefs . I then connected one of them to my amp's footswitch jack with a TRS cable.
The act of plugging in the TRS cable automatically turns on the Vibrato effect on the amp, and unplugging it turns the effect off. However there's just no way to program it to turn on and off with a command. There's also no way to control the reverb. I tried all the various settings for tips, ring, latch, etc. Nothing worked. Is this not possible?!