@Fae the reason I asked what has changed in version 4 is becaused these 2 projects got 1 way links working in version 3 by having a third converter hooked to the sender, so that it sees a signal in...

Are there changes in version 4+ of the MC200CM on how the communication between 2 converters work? I noticed that: 1. connecting the TX to the RX of the same unit reports the FX light 2. for 3 units,...