struggling how to set up 2 daq assist on labview in the same VI

[shaned]

hi all,

hope someone can help me out

I am currently using the scxi 2345 with some SCC FT01 feed through modules, these are just to record some voltages from some transducers.

What I am struggling with is setting up 2 daq assist on a single VI, it is coming back with a error stating specified resouce is reserved and then a window saying learn more about automatic handling. How would I also have these 2 values logged on the same graph or chart?

Anyone any ideas how to set these up.

I ideally want to have 3 daq assist in the same Vi but not sure if this is possible. It would be 1 for thermocouple input and 2 for voltage as stated above

many thanks

shane dover

[Dennis_Knutson]

The way it's usually done is to have a single DAQ Assistant that reads all channels. If, for some reason, you insist on 3 separate DAQ tasks, they would have to run sequentially. You do that by wiring the error in/error out connections together so that one task finishes befor the next one starts.

You can use the Split Signals function on the output of the DAQ Assistant (assuming you have a single DAQ Assistant) to get the separate channels, and then the Merge Signals on the two that want and wire the output of that to your graph/chart.

[CFAMS Brad]

Hi Shane and Dennis,

I've been working my way around the same type of problems, and I am currently re-writing everything to use on Asst. per board on my PXI chassis, so that no resources become reserved.

As a result, I have to separate the signals on the output dynamic data in order to do different post processing.  So I have been toying with staying with dynamic data, inputting dyn. data into an array, and inputing it into a cluster.  It seems that each has advantages and drawbacks, but arrays seem to be the easiest with which to work when splitting signals coming from a DAQmx Asst. and funneling some of the signals into a post-processing sub-VI.  The drawback to this is that time stamps in the Dyn. Data are lost if you want to record the data and the time of the reading. 

Question:  Is there an easy way to pipe Dynamic Data into a calculation subVI?  Is it workable after it's been split from other streams? 



Thanks,
Brad

[Dennis_Knutson]

You can use the Convert From Dynamic Data function (Express>Signal Manipulation palette). Right click on it and select Properties to choose the type of data you want to convert to. Waveform data types retain the timing information.

[CFAMS Brad]

Actually, unless I buggered it somehow other, this To/From Dynamic Data function was the first that I tried.  The problem may occur in splitting the signals, something that is mandatory if you only use one assistant per board with several different tasks going through it.  Once I had converted from dynamic data to any of the choices, split the signals, and piped into a sub-VI, I lost some of the information that had originally been with the dynamic data.  I guess the question should be, "Is there an easy way to split signals coming from dynamic data of one assistant and maintain the time stamp?"

Brad

[hannahW]

Are you wiring the data to a waveform graph? If so right click on the graph and uncheck the 'ignore time stamp' option?

If this isn't what you are seeing, what do you mean the data is lost? Can you post some code which demonstrates this problem

Thanks

Hannah

NIUK & Ireland

[CFAMS Brad]

I am plotting to a waveform chart.  Neither the chart nor the graph give the option of ignoring a time stamp when I right click.  I have posted the sub-VI that does the graphing.  It is set up to take in the clustered data, after it was converted from dynamic data in the main VI that calls this sub-VI.


Thanks for the input,

Brad

[hannahW]

Hey Brad

Can you post the vi that this subvi is used in so I can see how and why you are formatting the data in this way.

The data you pass into the subvi is a cluster with just doubles in, your not passing any timestamp data into the subvi so you wont be able to plot this to your chart.

If you post the other vi, I'll look at how to get the timestamp data too!

Thanks

Hannah

[CFAMS Brad]

Hannah,

Here is the main VI.  There are two other sub-VI's, but they are just post processing the voltage signals into pressure readings on two different types of sensors.  The fact that they involve different types of post-processing and are on the same board is likely the source of the problem, so if you could think of a creative way to work around it, that would be great.

Thanks,
Brad

[CFAMS Brad]

Forgot the VI...