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Strymon sells a MIDI Exp cable with a built-in isolator for their TRS MIDI devices: https://www.strymon.net/product/midi-exp-cable/

Engaging Looper mode in Timeline

Looper mode is engaged on the Timeline by holding down the Tap footswitch.

C#81 with values 0 and 127 will trigger the Tap footswitch press and release function respectively.

So, to simulate a long press to trigger the tuner, you can do this:

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You'll need to hold down the switch on the MC6 and then release it to simulate the same press and release on the Timeline.

Alternatively, you can use a Press action for both, and then add a delay inbetween to simulate a press/release on the Timeline with just a Press action on the MC6:

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