This is a completed project. Inside the black box is a MAX232 chip which converts the +- 12 volts of a normal RS232 signal into 0 and 5 volts respectively. On top of the box is the pinout for the free connector.
Pin 1, which is normally the CD (Carrier Detect) pin is used to power the MAX232 chip. So it is necessary to supply 5 volts to that pin when using this level shifter.
Pin 2, RX (Computer Receive), is where the project connects to send information to the computer.
Pin 3, TX (Computer Transmit), is where the project receives information form the computer.
Pin 4, DTR (Data Terminal Ready), is being used for special purposes. Bootloaders that I have used require the use of pin for resetting the device. This pin serve that purpose.
Pin 5 is the Ground connection.
The other serial connection is on the right side of the project box, this picture makes it difficult to see that.
Navigate to Electronics Information page for serial port pin outs and ASCII chart