Plot real time graph with data coming from serial port.

Hi there,

I'm trying to plot data coming from the serial port in real time. In detail I receive temperature, humidity and current consumption from serial port. I want to plot the values into a unique figure using subplot. My main problem is the x values. I want to plot the y date referred to the time elapsed from the script start.

With my script I obtain wrong values plotted on x axis.

This is my script:

MATLAB code
clear all
close all 
delete(instrfindall);
FSM_WAIT_START_S = 0;
FSM_READ_PAYLOAD = 1;
FSM_UPDATE_GRAPH = 3;
% Serial Port Settings
serialPort = serial( 'COM21' );
set( serialPort,'BaudRate', 9600 );
fopen( serialPort );
% Graph Settings
figure('units','normalized','outerposition',[0 0 1 1])
f1 = subplot( 3, 1, 1 );
title( 'Current consumption' );
ylabel( 'Current [A]' );
f1.XGrid = 'on';
f1.YGrid = 'on';
f1.YLim = [-5 5];
ani1 = animatedline('Color','r', 'LineWidth', 2 );
f2 = subplot( 3, 1, 2 );
title( 'Temperature' );
ylabel( 'T [°c]' );
f2.XGrid = 'on';
f2.YGrid = 'on';
f2.YLim = [0 50];
ani2 = animatedline('Color','b', 'LineWidth', 2);
f3 = subplot( 3, 1, 3 );
title( 'Humidity' );
ylabel( 'rH [%]' );
f3.XGrid = 'on';
f3.YGrid = 'on';
f3.YLim = [0 100];
ani3 = animatedline('Color','g', 'LineWidth', 2);
fsmState = FSM_WAIT_START_S;
charCnt = 0;
charBuffer = blanks(64);
secondsStartTime = second(datetime( 'now' ));
while(1)
  % Read Characters from serial port
  c = fscanf( serialPort, '%s', 1 );
  switch( fsmState )
      case FSM_WAIT_START_S
          if( strcmp(c, 'S') == 1 )
              cnt = 0;
              fsmState = FSM_READ_PAYLOAD;
          end
      case FSM_READ_PAYLOAD
          if( strcmp(c, 'E') == 1 )
              fprintf( 'Data buffer: %s\n', charBuffer );
              fsmState = FSM_UPDATE_GRAPH;
          else
              charBuffer( cnt + 1) = c;
              cnt = cnt + 1;
          end
      case FSM_UPDATE_GRAPH
          % Extract data
          measures = strsplit( charBuffer, ';' );
          current = str2double(measures(1, 3) );
          temperature = str2double( measures(1, 4) );
          humidity = str2double( measures(1, 5) );
          if( temperature ~= 0 && humidity ~= 0 )
              % Get current time
              t =  ceil((second(datetime( 'now' )) - secondsStartTime));
              % Update axes
              addpoints( ani1, datenum(t), current );
              f1.XLim = datenum([t - seconds(30) t]);
              datetick('x','keeplimits');
              addpoints( ani2, datenum(t), temperature );
              f2.XLim = datenum([t - seconds(30) t]);
              datetick('x','keeplimits');
              addpoints( ani3, datenum(t), humidity );
              f3.XLim = datenum([t - seconds(30) t]);
              datetick('x','keeplimits');
              drawnow;
          end
          fsmState = FSM_WAIT_START_S;
  end
end

Thanks in advance!

Answer 1

[Alberto Gontijo]

%MATLAB CODE TO PLOT VALUES FROM PORT IN REAL TIME

clc

clear all

close all

s1 = serial('COM26', 'BaudRate', 57600);

set(s1,'Terminator',35);

fopen(s1);

V=[];

val='';

time=200;

count=0;

f=0;

% **********************************************************************

% Read Serial values

tic

tt=toc;

while(tt<time)

val=fscanf(s1);

tt=toc;

%########################################################################

A=[];

B=[];

C=[];

b=[];

x=[];

j=1;

if(j<numel(val))

while(val(j)~='$')

a=val(j);

b=[b,a];

j=j+1;

end

A=[A,str2num(b)];

j=j+1;

b=[];

while(val(j)~='*')

a=val(j);

b=[b,a];

j=j+1;

end

B=[B,str2num(b)];

j=j+1;

b=[];

while(val(j)~='#')

a=val(j);

b=[b,a];

j=j+1;

end

C=[C,str2num(b)];

i=j;

b=[];

f=f+i;

end

x=[x,round(toc)];

if(~(isempty(A)&&isempty(B)&&isempty(C)))

subplot(1,2,1)

plot(x,A,'--rs','LineWidth',2,'MarkerEdgeColor','k','MarkerFaceColor','r','MarkerSize',5);

hold on % if u want this in different graph remove hold on and add "figure" command before each graph;

plot(x,B,'--rs','LineWidth',2,'MarkerEdgeColor','k','MarkerFaceColor','g','MarkerSize',5);

grid on;

subplot(1,2,2)

plot(x,(B/(A+B))*100,'--rs','LineWidth',2,'MarkerEdgeColor','k','MarkerFaceColor','m','MarkerSize',5);

hold on

plot(x,C,'--rs','LineWidth',2,'MarkerEdgeColor','k','MarkerFaceColor','b','MarkerSize',5);

grid on;

pause(.01);

end

end

hold off

fclose(s1);