Data Acquisition Idea Exchange

Hello,

How often you have build Labview applications using simulated DaqMx boards ...

And how often you were limited by the default behaviour of simulated boards ... ( Sinewave for analogic inputs, Counter square signal for digital inputs ... )

It would be nice to integrate in DaqMx simulated boards, the abilty to modify the default behaviour of simulated inputs ... thru dedicated popups

It would be nice, for each task linked to a simulated daqMx board, to launch a popup window ...

• For digital input, give the abilty to modify for each configured channel , the current binary value.
• For analog input, give the ability to choose between a fixed value, a sine wave, a square signal ... white noise ...
• For digital output, give the ability to view the current setted values
• For analog output, give the ability to view the current simulated output value on a waveform chart ...

A more powerfull tool could also integrate a simulated channels switching mechanism ... A simulated output could be linked to a simulated input 

This feature could be a good way to create an application which could simulate a complete process ... this application could be used to validate a complete system

(such a kind of SIL architecture)

Other idea .... A complete daqMx simulation API ...

• Creation of an API which could instanciate a simulated daqMx board (Wich could be seen via MAX)
  • Takes place of the actual limited daqMx simulated board
• This device could then be accessed by other application thru daqMx
• This API could have access to all channels of this simulated device.
• This API could force, programmatically, the value of the simulated input channels according to a realistic process model

Something like this ...

I've been in many threads and seen many, many more where the root issue stems from confusion about the way DAQmx Timing and DAQmx Read interpret the meaning of "# samples" very differently for Finite Sampling vs. Continuous Sampling mode.   (For example, here's just one of the times I tried to address that confusion.)

First, here's what causes the confusion:

• The 'samples per channel' input to DAQmx Timing is *crucial* for Finite Sampling tasks and usually *ignored* for Continuous Sampling tasks.
• The 'number of samples per channel' input to DAQmx Read has a default value of -1 when left unwired.  However, the *meaning* of this default value is *VERY* different,  resulting in very different behavior depending on whether the the task is configured for Finite or Continuous sampling.  (See the first link I referenced.)

While the relevant info is findable in the help, it also often clearly remains unfound.  I got to wondering whether some changes in the DAQmx API could help.

I'll describe one approach, but would definitely be open to better solutions.  The goal is simply to find *some* way to reduce the likelihood of confusion for rookie DAQmx users.

I picture adding more polymorphic instances to both the DAQmx Timing and DAQmx Read vi's, so there can be distinct instances for FInite vs Continuous sampling.

Further, I picture that the task refnum would carry sufficient type info related to this timing config, such that that downstream DAQmx functions can "know" what kind of Timing was set up -- Finite, Continuous, on-demand (the default if DAQmx Timing was never called at all), etc.

Then when that task refnum is wired into DAQmx Read, the most appropriate instance of DAQmx Read would show up.  And the corresponding input parameter names, help, default values, and default value *behavior* can all be tailored to that particular instance of DAQmx Read.  For example, perhaps the "# samples" input should become a *required* input for Continuous Sampling tasks, to force a decision and encourage further inspection of the advanced help.

Don't know how feasible something like this is, but it's definitely something that regularly trips up newcomers to DAQmx.

-Kevin P