I have a site in which we have a Jace 200 with Lon card into two Mcquay aircooled chillers. I have completed the AX cert and this is my first job with Jaces. And I have not did modbus ever. Here is what I think I can do. Purchase a modbus driver for this JACE and then wire the Aerco to it. I am not using the onboard rs485 port on this jace at this time. So wire the Aerco to this port of the Jace and discover it. Be patient this will be my first time doing this.....