SpeakerLink Connections and ConversionThe two grounds are for the master and slave comms connections. AES doesn't really need the ground, but either can also be used when SPDIF is required.
Tx and Rx are transmit and receive; used for RS232 connections (control / firmware updates), note a ground connection is also required.
TIA-B cable colouringAll the best,
Steve.
SpeakerLink to AES/EBU without Comms
SpeakerLink to AES/EBU plus C5 Comms
SpeakerLink to SPDIF plus C5 (inc. Slave Comms Return) OR M5/S5 Comms