Prev: how to get rid of array index
Next: table modification
From: Behnam Molavi on 3 Aug 2010 20:10
Hi everyone,

I'm using Matlab R2008a with data acquisition toolbox (version 2.12) to read data from an NI USB 6009 DAQ system. Matlab is running in bootcamp on a MacMini. I have a problem with my code which essentially reads values from DAQ in a loop and performs some processing on it. Even though data acquisition works fine most of the time, it sometimes stops halfway through acquisition for apparently no reason and I get a timeout error running getdata. When this error occurs, get(ai) shows that the ai object is still running, but the number of samples acquired is less than what it should be and no more data comes in until I restart the object. This is what my code boils down to:

x=daqfind;
if ~isempty(x)
stop(daqfind);
delete(daqfind);
end

Board=daqhwinfo('nidaq');
BoardID=Board.InstalledBoardIds;
ai=analoginput('nidaq',char(BoardID));
addchannel(ai,1);
set(ai,'InputType','singleEnded')
set(ai,'SampleRate',4000)
set(ai,'SamplesPerTrigger',Inf);
set(ai,'TimeOut',10);

for l=1:60
start(ai);
for k=1:100
[d,t]=getdata(ai,4000);
end
stop(ai);
end
delete(ai);
clear ai;


When the error happens, get(ai) output is as follows:

BufferingConfig = [256 30]
BufferingMode = Auto
Channel = [1x1 aichannel]
ChannelSkew = 2.08333e-005
ChannelSkewMode = Minimum
ClockSource = Internal
DataMissedFcn = @daqcallback
EventLog = [1x2 struct]
InitialTriggerTime = [2010 8 3 12 39 10.118]
InputOverRangeFcn = []
InputType = SingleEnded
LogFileName = logfile.daq
Logging = On
LoggingMode = Memory
LogToDiskMode = Overwrite
ManualTriggerHwOn = Start
Name = nidaqmxDev1-AI
Running = On
RuntimeErrorFcn = @daqcallback
SampleRate = 4000
SamplesAcquired = 356352
SamplesAcquiredFcn = []
SamplesAcquiredFcnCount = 1024
SamplesAvailable = 352
SamplesPerTrigger = Inf
StartFcn = []
StopFcn = []
Tag =
Timeout = 10
TimerFcn = []
TimerPeriod = 0.1
TriggerChannel = [1x0 aichannel]
TriggerCondition = None
TriggerConditionValue = 0
TriggerDelay = 0
TriggerDelayUnits = Seconds
TriggerFcn = []
TriggerRepeat = 0
TriggersExecuted = 1
TriggerType = Immediate
Type = Analog Input
UserData = []

NIDAQMX specific properties:
ExternalSampleClockSource = PFI2
ExternalScanClockSource = PFI7
HwDigitalTriggerSource = PFI0

Could this be because of using Windows on a mac?

Thank you for your help,
Behnam Molavi
 | 
Pages: 1
Prev: how to get rid of array index
Next: table modification