LH 5000 protocol to connect Greenstar via coms port

Trying to get a rate controller to connect to Greenstar via field connect cable to do variable rate. The connector communicates on LH5000 protocol which Greenstar can connect with, however greenstar will not accept communication is active, I presume "the handshake" isnt quite talking to each other..

Does anyone know more about the communications/protocol that greenstar needs to allow communication to be active.