There are two major method to get to serial programming mode. The main difference is that in one of them you need to press the RESET button (that's the whole method, basically) and in the other one, you need to send a string of characters.
The first method is used for troubleshooting and testing (similar to what we are doing here), and the second method is used by 'smart' RS232 devices, to control the Device Server. Both methods are documented in detail here .
This is the procedure for using the "regular" method of pressing the button:
|•||Perform the instructions under Establishing a Serial Connection with a Device Server. Select 38400, 8 bit, no parity.|
|•||Press the SETUP button.|
|•||The LEDs should start alternately blinking (green and red).|
|•||Go to the Programming Exercise and start programming the device.|
To know all there is to know about serial programming, please read Serial Programming in the full manual.