Here is the answer I posted for you on FB, didn’t realize you asked both places. If any follow up, let’s keep it here.
The MDP2 format for the sysex message would be "43 70 70 40 50 V" - then select "2" for bytes in value.
Next question would be how it is scaled. You can start by selecting Midi min of 40 and max of 240. (You have to set 2 bytes in value first or midi max value will be limited to 127).
If that doesn't work, a few other ways to suss out the coding:
- if tempo goes from 40.0 to 240.0, try 400 min, 2400 max
- if the board will transmit the sysex, turn on log and watch what the min/max values transmitted are, and how they follow the tempo control
- total brute force - choose 0 min 16383 as max, and scan through to see where tempo tracks the mdp2 control. Maybe divide into 1000k chunks rather than trying the entire range at once.
You didn't include the board specifics so I could do more research, but looks like a Yamaha from the 43 code. Since mfrs often stick to a common format, you might find a similar mfr layout where the tempo format is decoded.