how to output continuous signal using usb6008

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mado
mado 2014-3-24
回答： Julian 2016-11-4
i need your help to use ni usb6008 to output analog signal , the continuous signal is the control signal from PID controller, i used timer but i don't why it isn't working i used this code
% %%get connected devices
d = daq.getDevices
%create session
s = daq.createSession('ni')
s1= daq.createSession('ni')
%add analog channel s.addAnalogInputChannel('ID',channel num, 'measurement type')
% s.addAnalogInputChannel('Dev1',0:3, 'Voltage')%irradiance
s.addAnalogInputChannel('Dev1','ai0', 'Voltage')%irradiance
s.addAnalogInputChannel('Dev1','ai1', 'Voltage')%Temperature
s.addAnalogInputChannel('Dev1','ai2', 'Voltage')%current
s.addAnalogInputChannel('Dev1','ai3', 'Voltage')%voltage
% s.addAnalogInputChannel('Dev1','ai3', 'Voltage')%Temperature
%set(s.Channels,'InputType','SingleEnded')
%set(s.Channels,'Range',[-10 10])
%s.addAnalogInputChannel('Dev1','ai6', 'Voltage')%Temperature
AO=s1.addAnalogOutputChannel('Dev1', 'ao0', 'Voltage')
% set rate of scan 1000 scans/second , run for 30 seconds
s.Rate=1000;
s.DurationInSeconds =10
v.TerminalConfig = ' Differential';
%v.TerminalConfig = ' SingleEnded';
%_____________________________
%aquire data and process
lh = s.addlistener('DataAvailable', @plotData);
%store data
%h = s.addlistener('DataAvailable', @storedata);
% Analog Output
% duty cycle control signal x amplification
%for i=1:5
e= 18 - Vref
%end
IE=sum(e); %Integral of Error
% C = pid(20,10,0,'InputName','e','OutputName','u') % calculate control signal of pid
u=C*er
for i=1:length(u)
t = timer('TimerFcn', ' putsample(AO,u)',...
'StartDelay',0.2);
start(t)
end
s.startBackground()
s.wait()
delete (lh)
s.release()
it gives me error message
Error while evaluating TimerFcn for timer 'timer-1840'
Undefined function 'putsample' for input arguments of type 'daq.ni.AnalogOutputVoltageChannel

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回答（2 个）

Walter Roberson
Walter Roberson 2014-3-24
putsample() is only for the legacy interface.
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mado
mado 2014-3-24
in other questions i used singlescan but i want to output control signal which can't be one value , is there any solution ?is it available or should i switch back to legacy interface?

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Julian
Julian 2016-11-4
Ok, this answer is quite late, and not only focused on your actual code, but as I had a similar question just a short time ago, here's my answer:
The NI-USB6008 doesn't support clocked operations. That means you must trigger by yourself when you want to output a signal. If the need of real continuity and speed are not too important you can use a loop or something like that. If you really like to output continuously, it's better to use a DAQ Device that supports Hardware Triggering. Then you can pre-buffer your signals, can controll the output rate etc., in the background or in the foreground.

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