The Matlab interface to the communication server consists of a single
routine to interact with the communication server: mComm. Connection
to and interaction with the communication server are achieved by using
different arguments to the mComm function.

The mComm function performs three different functions: opening
communication with the communication server, setting data for a particular
robot's motor speeds, and closing communication with the communication
server.

The communication routines use port identifiers to maintain connections to
the communication server. By using this system a single Matlab session
would be able to make connections to multiple communication servers
or to make multiple connections to a single communication server. Each
time a connection to a communication server is opened with the 'open'
command it should later be closed with the 'close' command.


Typically the usage is of the form:
    result=mComm(command [, options])


The available commands are:
   'open' - Open a connection to the communication server
    Arguments: The character representation of the TCP/IP address of the 
               machine running the communication server 
    Returns: A port identifier used for future communication with the
             communication server.
    Example:    
        com_port=mComm('open','127.0.0.1');
        % Open a connection to the server on the machine with address
        % 127.0.0.1 (This is a loop back address - it will always connect 
        % to the machine on which the Matlab session is running)
        % And save the port identifier in the com_port variable

    'close' - Close the connection to the communication server
    Arguments: A port identifier created by the 'open' command
    Returns: Nothing
    Example:
        mComm('close',com_port);
        % Close a connection to the communication server that was 
        % created earlier and who's port identifier was stored in 
        % the com_port variable.

    'set' - Set the left and right motor speeds for a specific robot
    Arguments:
        A port identifier created by the 'open' command
        A numeric value representing the ID number set on the radio turret 
        dip switches of the desired robot
        A left motor velocity (in units of 0.78cm/s)
        A right motor velocity (in units of 0.78cm/s)
    Returns: 
        Nothing

    Example:
        mComm('set',com_port,1,5,-5);
        % Set the motor velocities on the communication server
        % who's port identifier is stored in com_port.
        % set the velocities for robot 1. 
        % set the left motor velocity to 5
        % set the right motor velocity to -5
        % Returns 0 on success