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Single value digital output and analog output with DT9804



I'm trying to get digital input and output and analog output working on my DT9804 using the DT-Open layers library while using software triggered A2D scanning. 

According to the manual,  for digital input, you cannot use single-value operations while an analog input scan is in progress. However, I was able to read the digital input values from A2D channel 16, so that's working fine.

For digital OUTPUT, the option of using something like A2D channel 16 does not seem to be available and the manual does not explicitly state whether single value digital output is possible when also using triggered A2D scanning. 

Can you tell me whether single value digital output is possible under these conditions?       

Finally, it appears that there is no way to use the analog outputs during triggered A2D scanning. 

Is there any workaround for this?





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Hello @boblev.

It's not stated in the DT9800 Series User's Manual, but you cannot perform a single-value digital output operation while the A/D subsystem is running.


If your analog input subsystem was configured to capture single values, as fast as the target system would allow, then you could call the digital inputs and/or digital outputs.

In the legacy DTx-EZ (VB 6.0) example, QuickDataAcq, the Scope module is configured for continuous capture on the analog input channels, while the Strip Chart module is configured for single-value captures.  Testing the Scope module when using either the single-value digital input or digital output modules does show an error, while using the Strip Chart with the single-value digital input or digital output modules does not.

The workaround would be to use single-value captures with the analog input subsystem or a different data acquisition device.



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Thanks for the additional information (and the definitive test you ran with QuickDataAcq). I don't think we could switch to using the single value analog input in our application (timing and overhead problems), but will give it a try.  

In the meantime, I was looking at the documentation for the DT9834 and I didn't see mention of similar limitations. Originally, this was the unit we were going to purchase, but Bob Vallee told us it is on backorder (estimated availability in 12/2023). Can you confirm whether the DT9834 does allow single value digital input/output and/or analog output when the A2D subsystem is running (in channel scan mode). 


We're going to be building several of these systems over the next year or so and may want to wait for the DT9834 to become available if it would allow us the additional capability.

Thanks in advance for your help with this.

Best wishes,






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