Hey, I just bouth this thing and am really confused. I dont understand how the serial commands ever reach the controller. I mean what digital pin does the serial command leave from. I tried to specify it using pinmode(10,Input) but still nothing. Some people have said that pin 2 is teh default for serial commands is that right?? and if so if i had two of these things how could I get both of them to work since there is only one pin 2.
Look up the NewSoftSerial library... http://arduiniana.org/libraries/newsoftserial/
It allows for serial communications from other than the standard RX/TX hardware pins if you need more than one serial channel.
Check here for a sample sketch, Google Code Archive - Long-term storage for Google Code Project Hosting. for the Pololu QIK 2s9v1 controller. It at least shows you how to use NewSoftSerial.Don't know if you are using that particular controller, so you might have to create your own code to send the serial commands if the CompactQik2s9v1.h library doesn't work...
Serial communications...
For two way communications, you need a common ground between the devices, a set voltage level (the arduino uses zero to positive five volts), a receive data pin (Arduino Digital Pin 0) and a transmit data pin (Arduino Digital Pin 1). During serial communications, the receive data pin listens for a alternating zero to five volt signal, and the transmit data pin switches between zero and five volts. Serial communications also has a data rate, measured in baud that has to be set.
Digital pins 0 and 1 are the Arduino's hardware serial port. You can use any other pairs of digital pins on the board to create a software serial port with the NewSoftSerial library for additional serial data channels.
Since the particular Pololu board you're using isn't mentioned, I can't look up the particular connections, but simple explanation is to transmit a serial signal to the Pololu board, you'd hook the Arduino TXData pin to the controller board's RXData pin (serial control input) and connect a common ground wire between the two.