@sundberg84 yes, you are right, CH340 chip works fine with arduino IDE but will not work with Vera Edge controller if you use it as serial gateway sketches, the reason is Vera Edge controller's build in USB driver not compatible with CH340 chipset.
For those newbies like me, don't waste your time to check anything if you able to see your serial gateway in IDE serial monitor " Gateway started " . Adopted from the original poster Burtonian, I am able to make it work last night follow the information in there and use additional USB to TTL converter device with FTDI chipset something like this one
http://www.aliexpress.com/item/1pcs-FT232RL-FTDI-USB-3-3V-5-5V-to-TTL-Serial-Adapter-Module-forArduino-Mini-Port/32256920717.html , attach 4 wires from this add on USB converter to your Arduino Nano as follow:
FTDI - USB Arduino Nano
VCC ------------------------------------------ 5V
GND ----------------------------------------- GND
RXD ------------------------------------------- RXD
TXD ------------------------------------------- TXD
Connect USB cable from Vera Edge controller to USB port on FTDI - USB (not Nano). Check back on Vera plug-ins you will see you gateway is there. I'm able to connect from the first try. Hope is help for somebody still frustrated like me couple days ago . Thanks again Burtonian, I'm very appreciated.