Improper use of putdata

Hello,

I try to control an industrial process through Matlab, NI DAQ-6052E and NI BNC-2110. That's why I need to output a continuous voltage, which is varying in time.

My problem is that using the putdata function, I get only a single value as output result (as you can see it bellow in the answer I get).

Any idea ?

Thank you in advance, Csaba

Here is the code :

%%Start NI DAQ-6052E
disp(' ');
disp('START');
disp(' ');
clear all;
close all;
%%Define ai
disp('Init ai: 100Hz, 10s');
ai = analoginput('nidaq', 'Dev1');
addchannel(ai, 0);
ai.SampleRate = 100;
t_in = 10;
ai.SamplesPerTrigger = t_in*ai.SampleRate;
ai.TriggerType = 'Immediate';
ai.Timeout = t_in+10 ;
%%Define AO
disp('Init AO: as ai');
AO = analogoutput('nidaq','Dev1');
addchannel(AO, 0);
set(AO,'SampleRate',ai.SampleRate);
set(AO,'TriggerType','Immediate');
t_out = t_in;
f_out = get(AO,'SampleRate');
n_out = f_out*t_out;
%%Reading input values
disp('Start acq');
start(ai);
wait(ai,t_in+1);
[value_in,t] = getdata(ai);
%%Generating output data
disp('Calc data out');
n_out = size(value_in,1);
data_out = zeros(n_out,1);
for i=1:1:(t_out*f_out)
  t(i,1)=i/(f_out);
  data_out(i,1) = 5-value_in(i,1);
end
*%%Outputting data
disp('Putdata');
putdata(AO,data_out);
s_out=get(AO,'SamplesOutput');
wait(AO,t_out+1);
start(AO);
s_out=get(AO,'SamplesOutput');
%%Verifying output
disp('# value read : '); disp(n_out);
disp('# data out : '); disp(s_out);
delta = n_out - s_out;
disp('DELTA : '); disp(delta);*
%%Display graph
disp('Graph');
fig = figure('Name', 'Test AI & AO on NI DAQ-6052E ND Matlab', 'NumberTitle','off');
subplot(2,1,1);
graph_in = plot(t,value_in);
set(graph_in,'Color','red','LineWidth',2)
title('Values read on ai')
axis([0 10 0 10])
set(gca,'XTick',0:1:10)
set(gca,'XTickLabel','0|1|2|3|4|5|6|7|8|9|10')
set(gca,'YTick',[0 1 2 3 4 5 6 7 8 9 10])
set(gca,'YTickLabel','0|1|2|3|4|5|6|7|8|9|10')
xlabel('Time [s]')
ylabel('Voltage [V]')
subplot(2,1,2);
graph_out = plot(t,data_out);
set(graph_out,'Color','black','LineWidth',2)
title('Data sent on AO')
axis([0 10 0 10])
set(gca,'XTick',0:1:10)
set(gca,'XTickLabel','0|1|2|3|4|5|6|7|8|9|10')
set(gca,'YTick',[0 1 2 3 4 5 6 7 8 9 10])
set(gca,'YTickLabel','0|1|2|3|4|5|6|7|8|9|10')
xlabel('Time [s]')
ylabel('Voltage [V]')
%%Stop NI DAQ-6052E
disp('Clear AO');
delete(AO);
clear AO;
disp('END.');
disp('*********');
disp(' ');

And here is the answer :

START
Init ai: 100Hz, 10s
Init AO: as ai
Start acq
Calc data out
Putdata
*# value read : 
      1000
# data out : 
   1*
DELTA : 
 999
Graph
Clear AO
END.
*********

Answer 1

[Chirag Gupta]

Put the wait command after start(AO) in your code.

putdata queues the data in the engine and start(AO) would start the output.

 putdata(....)
 start(AO);
 wait(AO,....)
 ...

[Chirag Gupta]

Also you should use SamplesAvailable property to check for the number of samples available for output.

So:

putdata(...)

samp_out_avail = get(AO,'SamplesAvailable');

start(AO);

while (AO.Running)

s_out = get(AO,'SamplesOutput')

pause(0.5)

end