Thanks Babybear and Gil.
I have done that but still no go. I will buy another 9ch board to see if that is the problem.
The strange part is that the output will flash the 2 wire LED string intermittently coinciding to some of the effects for my mega tree which is set to start at CH 513 on universe's 2 to 6. This indicates that some data is passing from Xlights to Falcon to DMX board but from the wrong Universe and Channel number.
I have set up an effect of a line in red in Xlights on CH1, Universe 1 and tried the 9ch board to all 4 comms ports on the Falcon but mostly on Comm port 1. The Falcon ports are DMX ports and the Falcon is set up Output 1, DMX, Start CH 1.
Time to surrender.