Hmm....indeed, it seems the top inverter should be on (green) as well. What type of data is in these ModBus registers? Judgin by the value showing "0.0000" it is not a boolean type. Could the value in the register be smaller than 0.0000? Or perhaps it is beign read as a -0.0000. Yes it can happen, if the register is supposed to be a signed short and somehow gets the msb set you will have a negitive zero, which when cast to a boolean might be a 1. (I don't know how Brains handle type casting).