How can I setup the IO expansion shield V.5 for RS455?

Hello everyone:
I am trying to use IO expansion shield for connection arduino to pc.
But it is not working for me if I connect a USB-RS485 connector to shield
and using external 12V DC power.
It works fine if I use arduino usb-RS232 wire as a power supply.
So, if any one can help me to setup this shield.
Thanks for your helps.
I am trying to use IO expansion shield for connection arduino to pc.
But it is not working for me if I connect a USB-RS485 connector to shield
and using external 12V DC power.
It works fine if I use arduino usb-RS232 wire as a power supply.
So, if any one can help me to setup this shield.
Thanks for your helps.
2013-04-23 16:11:41 The problem is solved because of the batteries. Many thanks to your help.
dah1214

2013-04-23 10:44:35 Hi
Have you checked the "A" & "B" is connect correctly? you mean that you power the Arduino board with 12V?
Can you give more details ?
Best
Phoebe
Have you checked the "A" & "B" is connect correctly? you mean that you power the Arduino board with 12V?
Can you give more details ?
Best
