Thanks for the advice I am starting to get an understanding. This is my understanding.
1. The Celestron NexStar software does not require any special settings on the SynScan contoller. Just plug the RS232 cable in. This makes sense as Celestron and Skywatcher are owned by the same corporation.
2. The ASMOD drivers require the SynScan Contoller to be set to "PC Direct Mode" before connecting. ASCOM recommends that a dongle is the peferred approach and "PC Direct Mode" should only be a temporary approach
3. Using the ASMOD drivers the SysScan Contoller can be completely removed and replaced with a "dongle". The dongle apparently squares up the TTL voltage levels on the serial RS232 interface.
I was a bit confused by the dongle reference. In the past decades, a dongle was a security device plugged into a RS232 port to stop illegal use of copied software.
Thanks and Kind Regards
Rob