Mesh - here's a clip from your Alesis manual:
The QS keyboard has three back-panel pedal jacks, marked [SUS PEDAL], [PEDAL 1] and [PEDAL 2].
[SUS PEDAL] is designed to work with any standard momentary footswitch. It doesn’t matter whether the footswitch is normally open or closed, so long as you plug it into the jack before powering up your QS; the instrument will automatically sense the footswitch’s polarity and calibrate itself accordingly.
[PEDAL 1] and [PEDAL 2]. are designed to work with a Roland EV-5 volume pedal (or its equivalent).
The QS’s factory defaults assign sustain to the [SUS PEDAL] jack and overall instrument volume to the [PEDAL 1] jack, but you can change these settings at any time if you want to. There are lots of interesting possibilities to explore. A starter example: using a footswitch to turn vibrato on in a program, and using a volume-type pedal to
control vibrato speed.
If your sustain footswitch responds backwards (i.e., notes sustain unless the footswitch is pressed), then turn off your QS and make sure the footswitch plug is fully inserted into the [SUS PEDAL] jack. When it is, turn the instrument’s power back on while keeping your foot off the footswitch.