Sorry, still need to clear up a couple of things. I understand the gist of it now.
On the radio RRC I configure Serial Settings COM2 mode to 'mode 2 ICOM CI-V'
On the control RRC do I configure Serial Settings COM2 mode to 'mode 2 ICOM CI-V' as well and also set 'Use USB COM port as COM2'.
The microbit cable you pointed to had a power connection. The cables available over here are powered from the RS232 interface by raising DTR (example
http://www.g4zlp.co.uk/unified/IcomCAT.shtml) and are much less expensive. Is it possible to use one of these?
73 Bob