I have it attached to my Arduino Uno R3 on pins 8 and 9 and I am using software serial in the code.
Don't use SoftwareSerial with the RN-XV. It's quite picky about the serial timing and the SoftwareSerial cannot fulfill the needs of the RN-XV. I never got it running using SoftwareSerial but it runs like a charm on the hardware serial.
#include <SoftwareSerial.h>
SoftwareSerial wifiSerial(8,9);
void setup()
{
Serial.begin(9600);
delay(500);
Serial.print("$$");
}
void loop ()
{
Serial.read();
}
You instantiate a SoftwareSerial instance but you're printing to the hardware serial interface and read from there.
From the hardware side mine is connected using an XBee shield (from Iteadstudio) that does the level conversion for the serial pins. Without that level conversion you may have destroyed the RN-XV already, the datasheet specifies "3V3 tolerant" whatever that may mean. In the electrical characteristics the voltage is specified with 3.7V max.