How to pack value into an vector?

Hi every one.

I have trouble packing values that are calculated into a vector hence what it does when I plot is that it only shows single plot point. Instead of plotting the whole values in pre-define vectors. Thank you in advance for help me out. I'm appreciated.

This is my code:

function run()

persistent gradual_opening_of_tap_file;
%% Set timer on
tmr = timer('ExecutionMode', 'FixedRate', ...
    'Period', 1, ...
    'TimerFcn', {@timerCallback});

gradual_opening_of_tap_file = fopen('Gradual_opening_of_tap.txt','r'); % Open gradual opening of tap data


start(tmr);
    function timerCallback(hObj, eventdata)
     
        fgetl_tap_on_data = fgetl(gradual_opening_of_tap_file);
        gradual_opening_of_tap = sscanf(fgetl_tap_on_data,'%f V,%i counts, %i ms');
        V_s = 5;
        p = 1000;
        g = 9.81;
        pressure_tap_on = [];
        flow_rate_tap_on = [];
        head_tap_on = [];
        hydraulic_tap_on = [];
        
        p = gradual_opening_of_tap(1);
        counts = gradual_opening_of_tap(2);
        time = gradual_opening_of_tap(3)/1000;
         
        
        if ischar(fgetl_tap_on_data)
           
            %% Im not too sure how to pack all these value back into pre-declared varibles for continuous plotting

            pressure_tap_on(end+1,:) = (p/V_s - 0.04)/0.0018; 
            flow_rate_tap_on(end+1,:) = counts /330*(time/1000);
            head_tap_on(end+1,:) = pressure_tap_on/(p*g);
            hydraulic_tap_on(end+1,:) = flow_rate_tap_on .* pressure_tap_on/1000;
                      
            subplot(2,2,3)
            plot(time, pressure_tap_on,'ro');
            subplot(2,2,4)
            plot(time, flow_rate_tap_on, 'ro');
            subplot(2,2,2)
            plot(flow_rate_tap_on, head_tap_on, 'ro');
            subplot(2,2,1)
            plot(flow_rate_tap_on, hydraulic_tap_on,'ro');
            
%             set(a , 'XData', time, 'YData', pressure_tap_on)
%             set(b , 'XData', time, 'YData', flow_rate_tap_on)
%             set(c , 'XData', flow_rate_tap_on, 'YData', head_tap_on)
%             set(d , 'XData', flow_rate_tap_on, 'YData', hydraulic_tap_on)
        else
            stop(tmr)
           fclose all;
        end
        
    end