Just to let everyone know. My Solar Assistant is working 100%, first time around, using this cheap RS485 adapter https://www.communica.co.za/products/bmt-usb-rs485-ttl-converter-ftdi
Pins 1,2,3 on the RJ45 go to B, A and Ground, respectively.
@Solarcrazy- I'm experiencing a similar issue to what you had. When grid fails, the inverter carries the essential load with no problems. However, when the grid restores, the inverter will drop the essential for about a minute and then restore. This does not happen every time - probably 1 out of 10 times. In your last message you refer to a "missed out cable connection" that your installer fixed. What cable could this have been that has this kind of impact on the system?