Grata
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Posts posted by Grata
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based on the configuration, minretriggerperiod should be:
(1 CGL * 100 CGLs per trigger)/500kHz + 2us = .000202s
This implies a max retrigger of 1/.000202s or 4950Hz.
the configuration calls for a retrigger at 300Hz which should be supported, correct?
If there is only 1 CGL (AI0) and samples per channel is set to 100 and scan count is 100, should there be only 100 samples collected per trigger?
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We are using an external trigger and an external clock to acquire a signal on AI0 of a DT9844.
The external clock is a square wave, 50% duty cycle, 500KHz
The external trigger is a square wave, 50% duty cycle, 300Hz.
The AI0 input is a a square wave, 50% duty cycle, 150Hz, 0 to 5V
AI0 is configured to scan the channel list (AI0 only) 100 times, to collect 100 samples per scan and to buffer a total of 10000 samples to display.
We anticipated the displayed buffer to have 10000 samples, looking like a square wave of 100 samples at 5V followed by 100 samples of 0V repeated 50 times.
We were able to configure an NI6343 to collect in this manner and the displayed output was what was expected. The block diagram and output display from the NI6343 are show below. The display shows the signal for one triggered scan and the complete buffer.
Also shown below are the block diagram for the DT9844 and the output display. While the display for one triggered scan is what was expected, the complete buffer was not.
The number of samples per scan, scan count and buffer size may not be configured properly and are likely the cause for the 10000 buffered samples to seem to be random.
It there an improper configuration for these parameter in the block diagram?
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Is there a way to perform the inversion on the DT9844?
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Changing to low level makes the pulses occur when the 1Hz signal is low.
With gating set to high, and the Counter 1 100Hz 5% duty cycles, when the 1Hz signal goes high, the Counter 1 output goes high, 9.5ms later for 5 ms. How can it be configured so that it goes high with the 1Hz signal for 5ms and goes low for 9.5ms?
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When configuring as described, there seems to be a non trivial delay between the rising edge of the 1Hz signal on the "Counter 1 Gate" pin and the "Counter 1 Out" pin. Is it that the output signal on "Counter 1 Out" starts low, then goes high? If so, is there a way to reverse this so that "Counter 1 Out" starts high, then goes low?
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Fausto, thank you for the example.
In your example where the 1Hz 50% duty cycle signal cannot be adjusted, can the counters be configured to generate the 1Hz 5% signal for the Counter 1 gate when the 1Hz 50% goes high and when it goes lo? This would allow the 5 100Hz pulses to be generated each time the 1Hz 50% duty cycle transitions.
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When controlling a DT9844 from LABView, is there a way to configure the counters to produce a finite series of pulses each time a gate is measured?
For example, if CTR0 is set as a gate based on a rising edge, if it sees a rising edge, can CTR1 be configured to produce say 5 pulses, each pulse being 50% duty cycle square wave with a 10ms period then stopping until the next rising edge is seen on CTR0?
If CTR0 sees a 1Hz square wave, each time CTR0 goes hi, CTR1 would generate a 50ms output of a 100Hz, 50% duty cycle square wave followed by lo for 950ms.
To cross reference, some NI products support Implicit Timing and Pause Triggers on Counters. See:
https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019M9CSAU&OpenDocument=&l=en-US
and
https://www.ni.com/docs/en-US/bundle/ni-daqmx/page/mxcncpts/gensnglefinconttrains.html
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Can the DT9844 be controlled in LABView? If so, can External Retriggering be configured for the DT9844 in LABView? What needs to be installed for LABView to recognize a DT9844?
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It does not appear to be supported in QuickDAQ either.
It is supported in LABView?
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The DT-9844 user manual indicates that it supports External Retriggering. Can DASYLab be configured to make use of this functionality?
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We have a DT9844 which can we can connect to in MATLAB and operate. We have downloaded DASYLab and Instacal. We have enabled Data Translation and Measurement Computing in the DASYLab configurator. Instacal does not recognize our DT-9844 so DASYLab does not either.
How do we get the DT-9844 recognized in DASYLab for evaluation?
Configure DT9844 for 2 Channel Analog Input
in Measurement Computing (MCC)
Posted
We have attempted to configure a DT9844 to read 2 separate SE analog input channels and display the output as a function of time using LabVIEW.
The read rate is set to 300klHz.
On AI0 we have an input with V~=2.6V (constant).
On AI1 we have an input V nominally at 2.27V that can increase to ~2.8V.
Measuring the V at the AI terminals with an accurate precision DMM, we have confirmed that the V on AI0 is steady at 2.603V and that AI1 ranges from 2.27 to 2.7V.
The V measured by the DT9044 on AI1 seems to accurate with respect to the DMM to within 1mV.
However, as the V changes on AI1, a V change is produce on our AI0 display. We suspect there is an AI configuration error. Our sample code is show below and attached. Any suggestions of where the configuration error is would be greatly appreciated.
DT_nCH_nSAMP_Cont.vi