Position from two signals Encoder A and B using counters in a session based DAQ

Hi all,

I'm having some trouble getting the position of one tool. This is because the position should be computed from two quadrature signals (encoder A and encoder B), which I wanted to acquire with a NI cDAQ-9178 chassis and a NI 9402 module under Matlab 2012a (7.14, drivers are DAQmx-9.5.1).

The problem is that during the acquisition the second counter 'ctr1' of my session is 0 at anytime while the real signal is correct (I've checked with an oscilloscope). Here is my code :

function MultipleCounterTest

% Getting updated hardware informations
d.Chassis = daq.getVendors;

% Creating measurement session 1
s = daq.createSession(d.Chassis.ID);

% Adding channels to the measurement modules
s.addAnalogInputChannel('cDAQ1Mod2','ai2','Voltage');
s.addCounterInputChannel('cDAQ1Mod4','ctr0','EdgeCount');
s.addCounterInputChannel('cDAQ1Mod4','ctr1','EdgeCount');
s.DurationInSeconds = 1;
s.Rate = 1*1E2;

l = s.addlistener('DataAvailable',@f);

    function f(src,event)
        hold on;
        figure(1);
        A = event.Data(:,2);
        h = plot(event.TimeStamps,A);
        set(h,'Visible','On');
        set(gca,'Visible','On');
        set(gca,'XLim',[0,s.DurationInSeconds]);
        set(gca,'YLim',[-max(A)/5,max(A)*6/5]);
        set(h,'LineStyle','-');
        set(h,'LineWidth',1);
        set(h,'Color','Green');
        set(h,'Marker','o');
        set(h,'MarkerSize',1.5);
        set(h,'MarkerEdgeColor','Green');
        set(h,'MarkerFaceColor',[1,1,1]);

        hold on;
        figure(2);
        B = event.Data(:,3);
        h = plot(event.TimeStamps,B);
        set(h,'Visible','On');
        set(gca,'Visible','On');
        set(gca,'XLim',[0,s.DurationInSeconds]);
        set(gca,'YLim',[-max(B)/5,max(B)*6/5]);
        set(h,'LineStyle','-');
        set(h,'LineWidth',1);
        set(h,'Color','Black');
        set(h,'Marker','o');
        set(h,'MarkerSize',1.5);
        set(h,'MarkerEdgeColor','Black');
        set(h,'MarkerFaceColor',[1,1,1]);
        hold off;
    end

% Executing acquisition
s.startBackground();
s.wait();

% Deleting measurement session
delete(l);
s.stop;
s.release;
end

Is there any way to get both outputs of two counters ('ctr0' ad 'ctr1') from a same module ('cDAQ1Mod4') working in the same session ('s') in matlab with a session based DAQ and without using?

pause(0.1);
s.inputSingleScan();
pause(0.1);
s.inputSingleScan();

Thank you very much, your help would be much appriciated...

Csaba

[Csaba]

I've also checked the following links without much success, because each time only one counter ('ctr0') is used :

http://www.mathworks.ch/products/daq/demos.html?file=/products/demos/shipping/daq/demo_countertimer_countingpulses.html

http://www.mathworks.it/matlabcentral/answers/6258-nidaq-continuous-and-background-acquisition

http://www.mathworks.it/matlabcentral/newsreader/view_thread/313543

[Manisha]

Does inputSingleScan give you the correct answer? Also do you only get all zeros with startForeground also?

Answer 1

[Csaba]

I also tried to dispatch the counter sessions in two different sessions like this :

function DispatchingCounterTest

ClearWorkspace();
AddBreakpoint('DispatchingCounterTest',0);

global Time;
global Data;
persistent NumberOfCall;
if not(exist('NumberOfCall','var')) || isempty(NumberOfCall)
  NumberOfCall = 0;
  Time.Stamps = [];
  Data.A = [];
  Data.B = [];
  Data.C = [];
  Data.F = [];
end

% Getting updated hardware informations
d.Chassis = daq.getVendors;
d.Modules = daq.getDevices;

% Creating measurement session 1
s = daq.createSession(d.Chassis.ID);
t = daq.createSession(d.Chassis.ID);

% Adding channels to the measurement modules
s.addAnalogInputChannel('cDAQ1Mod1','ai0','Voltage');
s.addCounterInputChannel('cDAQ1Mod4','ctr0','EdgeCount');
set(s,'DurationInSeconds',10);
set(s,'Rate',100);

t.addAnalogInputChannel('cDAQ1Mod2','ai2','Voltage');
t.addCounterInputChannel('cDAQ1Mod4','ctr1','EdgeCount');
set(t,'DurationInSeconds',get(s,'DurationInSeconds'));
set(t,'Rate',get(s,'Rate'));

l = s.addlistener('DataAvailable',@f);
m = t.addlistener('DataAvailable',@f);

    function f(src,event)
        hold on;
        if(strcmpi(src.Channels(1,1).Device.ID,'cDAQ1Mod1'))
            disp(strcat('ctr0 called at',32,datestr(now,'HH:MM:SS.FFF')));
            Color = 'Black';
            Time.Stamps = [Time.Stamps;event.TimeStamps];            
            Data.C = [Data.C;event.Data(:,1)];
            Data.A = [Data.A;event.Data(:,2)];
        else
            disp(strcat('ctr1 called at',32,datestr(now,'HH:MM:SS.FFF')));
            Color = 'Green';            
            Data.F = [Data.F;event.Data(:,1)];
            Data.B = [Data.B;event.Data(:,2)];
        end
        Handle = plot(event.TimeStamps,event.Data);
        set(Handle,'Visible','On');
        set(gca,'Visible','On');
        set(Handle,'LineStyle','-');
        set(Handle,'LineWidth',1);
        set(Handle,'Color',Color);
        set(Handle,'Marker','o');
        set(Handle,'MarkerSize',0.5);
        set(Handle,'MarkerEdgeColor',Color);
        set(Handle,'MarkerFaceColor',[0,0,0]);
    end

% Executing acquisition
t.startBackground();
s.startBackground();
s.wait();

% Plotting data
figure(2);
hold on;
Data.A = (Data.A-Data.A(1))*333.4721;
h = plot(Time.Stamps,Data.A);
set(h,'Visible','On');
set(gca,'Visible','On');
set(gca,'XLim',[0,t.DurationInSeconds]);
set(gca,'YLim',[-max(Data.A)/5,max(Data.A)*6/5]);
set(h,'LineStyle','-');
set(h,'LineWidth',1);
set(h,'Color','Green');
set(h,'Marker','o');
set(h,'MarkerSize',0.5);
set(h,'MarkerEdgeColor','Green');
set(h,'MarkerFaceColor',[1,1,1]);

% Plotting data
h = plot(Data.B);
set(h,'Visible','On');
set(gca,'Visible','On');
set(gca,'XLim',[0,t.DurationInSeconds]);
set(h,'LineStyle','-');
set(h,'LineWidth',1);
set(h,'Color','Red');
set(h,'Marker','o');
set(h,'MarkerSize',0.5);
set(h,'MarkerEdgeColor','Red');
set(h,'MarkerFaceColor',[1,1,1]);
hold off;

% Plotting data
figure(3);
hold on;
h = plot(Data.C);
set(h,'Visible','On');
set(gca,'Visible','On');
set(gca,'XLim',[0,t.DurationInSeconds]);
set(gca,'YLim',[-max(Data.C)/5,max(Data.C)*6/5]);
set(h,'LineStyle','-');
set(h,'LineWidth',1);
set(h,'Color','Black');
set(h,'Marker','o');
set(h,'MarkerSize',0.5);
set(h,'MarkerEdgeColor','Black');
set(h,'MarkerFaceColor',[1,1,1]);

% Plotting data
h = plot(Data.F);
set(h,'Visible','On');
set(gca,'Visible','On');
set(gca,'XLim',[0,t.DurationInSeconds]);
set(gca,'YLim',[-max(Data.D)/5,max(Data.D)*6/5]);
set(h,'LineStyle','-');
set(h,'LineWidth',1);
set(h,'Color','Blue');
set(h,'Marker','o');
set(h,'MarkerSize',0.5);
set(h,'MarkerEdgeColor','Blue');
set(h,'MarkerFaceColor',[1,1,1]);

% Deleting measurement session
delete(l);
delete(m);
s.stop;
t.stop;
s.release;
t.release;
end

But it didn't worked either. Data.B stays at 0 all the time. Anyone with a new idea ?

Thanks,

Csaba