It is funny how small, simple thing can get so complicated.
I have tried to demonstrate how things are working, but cant get even run the spindle in one direction - UCCNC software keeps giving message just after start that it was disconnected ....

Disconnected both DI1 and DI2 and than I can start UCCNC... once connected to DI1 for FWD function, after M3 command UCCNC just gives message that UC300 have been disconnected...

Im bit confused now...

Didn't had enough time today to look further, but will do this tomorrow... I will start with only FWD direction this time :D