pumpobj(comPort)

function serialObject = pumpobj(comPort)
% PUMPOBJ Returns the serial object for Jasco pumps
% serialObject = pumpobj(comPort) returns the serial object for Jasco pumps
% given a suitable COM port number (unsigned integer: 1-255).  If an object
% already exists on that COM port (open or otherwise), returns an error.

% Normal usage:

% e.g. serialObject = pumpobj(9) - returns a serial object for the Jasco pump
% on COM9


% checks the number of arguments
error(nargchk(1, 1, nargin))

% Error handling
if ~isscalar(comPort) || comPort ~= uint8(comPort) || ~comPort
    % errors
    error('comPort must be an unsigned integer from 1 to 255')
end

% if object on specified COM port exists, errors, otherwise creates
% serial object

% initialises variables
serialPort = sprintf('COM%d', comPort);

% if serial object does not exist, defines serial object and opens it
if isempty(instrfindall('Port', serialPort))
    % creates the serial object (note that the first terminator is for
    % reading, and the second terminator is for writing)
    serialObject = serial(  serialPort,...
        'BaudRate', 4800,...
        'DataBits', 8,...
        'Parity', 'none',...
        'StopBits', 2,...
        'Flowcontrol', 'hardware',...
        'Terminator', {'CR/LF', 'CR'},...
        'TimeOut', 1);
    
else
    % errors
    error('Object(s) already exist on this serial port')
end