The Metasys N2 bus follows the RS-485 standard for its physical and electrical characteristics. It runs at 9600 BD, half duplex using N2+, N2-, and Ref wires. Our S4 Open appliances are pre-configured to have all Com ports operate in RS-485 mode.
If you run any of the JCI Metasys configuration or commissioning tools HVAC Pro, GX-9100, etc. from your labtop or another Windows PC and want them to communicate the the N2 bus via their COM port you'll have to utilize either a USB to RS-485 or a RS-232 to RS-485 converter.
We have been using RS-485 converters from B&B Electronics www.bb-elec.com to connect our PCs to the N2 bus.
For RS-232 to RS-485 we use their model 485SD9TB
For USB to RS-485 (N2 bus) we use their model number 485USBTB-2W
The USB Serial Port technology has become so standardized that most manufacturers' products should work fine although the B&B products are the only ones we have tested. Note that you may have to a...