The relay needs MIDI access to reach your FM-1s.
Clock when stopped keeps the clock running while stopped, so every unit already shows the tempo. A unit switched on or plugged in during playback waits for the late-join point, then starts in phase.
ECHOFIELD units also get START / STOP as CC 104, so they start and stop with the rest even on firmware before clock support. Their delay time is set by CC 85 to this note value at the current tempo.
Demo units add a virtual SLOOP and ECHOFIELD, so you can try the relay without hardware. Real FM-1s connect by USB, through a hub for more than one. The first four ticked ports take the slots.
Space play / stop · R restart · T tap · ↑ ↓ tempo ±1 · ⇧↑ ⇧↓ ±10 · 1–4 select slot · O slot on / off · P ping · M menu
Sends standard MIDI clock (F8, 24 PPQN), START (FA) and STOP (FC). PING plays a short note on the unit. · Source on GitHub