Re: Problems with HwDigital Triggering in Matlab with the National Instruments 6221

Hi David,

This is an interesting use case. Since you seem to have a valid license that is on maintenance, I would recommend contacting The MathWorks Technical Support department. We could then attempt to replicate the behavior that you are seeing with a similar hardware setup. Please submit a service request from the following location:

http://www.mathworks.co.uk/support/contact_us/index.html

When submitting your service request, please provide us with the following information:

1. The output of the command:

daqsupport

entered at the MATLAB command prompt.

2. The output of the command:

ver

for operating system information, license number, processor information etc.

3. A short and concise code segment that reliably reproduces this issue, and
4. For the benefit of the engineer who works with you, a detailed description of your hardware setup.

Thanks
Siddharth

"David " <d.garner@xxxxxxxxxxxxxx> wrote in message <h3ndud$bq3$1@xxxxxxxxxxxxxxxxxx>...
I'm having some problems with triggering the USB 6221 using the Matlab Data Aquisition Toolbox. I'm using TriggerType = HwDigital and I have hard-wired one of the two AO channels to PFI5 and am using this as my HwDigitalTriggerSource. Following triggering, I am gathering 50 samples from only one of the analog inputs using the other analog output as my convert & sample clock, again hard-wired to PFI6 and PFI7 which are my ExternalSampleClockSource and my ExternalScanClockSource, respectively.

My desired triggering rate is 1 kHz. The problem is that at this rate the DAQ only triggers on two consecutive triggering cycles, and then does not re-trigger until approximately 20 ms has elapsed.

I have copied and pasted the results of get(ai) in matlab below. I'd be grateful for any help or advice. David.



BufferingConfig = [4096 384]
BufferingMode = Auto
Channel = [1x1 aichannel]
ChannelSkew = 4e-006
ChannelSkewMode = Minimum
ClockSource = ExternalSampleAndScanCtrl
DataMissedFcn = @daqcallback
EventLog = [1x374 struct]
InitialTriggerTime = [2009 7 16 14 9 10.0642]
InputOverRangeFcn = []
InputType = SingleEnded
LogFileName = D:\MATLAB\test.daq
Logging = Off
LoggingMode = Disk&Memory
LogToDiskMode = Overwrite
ManualTriggerHwOn = Start
Name = nidaqmxDev2-AI
Running = On
RuntimeErrorFcn = @daqcallback
SampleRate = 52356
SamplesAcquired = 18650
SamplesAcquiredFcn = []
SamplesAcquiredFcnCount = 1024
SamplesAvailable = 18650
SamplesPerTrigger = 50
StartFcn = []
StopFcn = []
Tag =
Timeout = 1
TimerFcn = []
TimerPeriod = 0.1
TriggerChannel = [1x0 aichannel]
TriggerCondition = NegativeEdge
TriggerConditionValue = 0
TriggerDelay = 0
TriggerDelayUnits = Seconds
TriggerFcn = []
TriggerRepeat = Inf
TriggersExecuted = 373
TriggerType = HwDigital
Type = Analog Input
UserData = []

NIDAQMX specific properties:
ExternalSampleClockDriveLine = PFI9
ExternalSampleClockSource = PFI6
ExternalScanClockDriveLine = PFI10
ExternalScanClockSource = PFI7
ExternalTriggerDriveLine = PFI8
HwDigitalTriggerSource = PFI5


.

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