1. Engls with standard MIDI port (Invader, Morse, ...) - any MIDI pedal/controller/device, able to send Program Change message
2. Engls with S.A.C. port (Powerball II, ...) - ENGL S.A.C. equipped pedal (Z-9)
3. Engls with "parallel port" 25-pin connector (Savage, ...) - Engl Z-10 footswitch, Engl Z-11 MIDI switcher
4. Engls with "serial port" 9-pin connector (Powerball I, ...) - Engl Z-5 footswitch
5. Engls with standard channel/function switching jacks - most latching footswitches with stereo jacks, in case of MIDI control some converter is necessary, i.e. NUX PMS-2 Midi Switcher