I have done with i2c between two 20X2 communicate use LEDs, send command use i2cmaster, and receive different i2cslave with if hi2cflag = 0 then, hi2cflag = 0, get hi2clast,b1 for partX2 only.
Anyway, I have trying use 08M2 send to 18M2 receive, same i2cmaster both, for practice with led first...