This all makes sense now.... (I think)

Catalyst, MA3D Visualiser and a PC running MA 'On PC' were set to pick up a DHCP address in the range of 2.x.x.x. (actually with subnet 255.255.255.0 - due to linksys router limitation) The MA board was plugged in to the same network (obviously). However, the PCs MA3D visualiser running 'On PC' could not communicate with the real board via the MA protocol, because the PC IP address was 2.x.x.x and GrandMA protocol works on 192.168.0.x.

However, when the IP address of the MA3D Visualiser and MA 'On PC' was changed to 192.168.0.x it was able to communicate with the board, and the board was still able to communicate with the Mac running catalyst (2.x.x.x).

So - the IP address configuration on the board refers to the MA protocol ONLY(192.168.0.x) - not artnet! (which is not obvious at first! and not explained in any manual.) The bit of the desk that produces artnet is set internally to the address range of 2.x.x.x and is not configurable (as it says on the desk's artnet screen).

Does the desk use two IP addresses, as suggested, - one for each protocol, rather than using a 255.255.255.255 broadcast message? Will see if someone from MA can confirm this...

either way - it does comunicate with Catalyst in the 2.x.x.x artnet range, straight out the back of the desk. (and its easier programming on an MA!)

S