Real-Time Measurement and Control

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Measuring DC voltage

Hi Am trying to Measure the Voltage of a 9V Battery.After disconnecting the battery the value of the voltage in the indiacator in the VI goes down very slowly instead of falling to zero immd.Am using AI sample channel.vi to get the output from the virtual channel.How can I bring it down to zero as soon as the battery is disconnected?
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Hello;

Once you disconnect the signal source from the Analog Input channel, the ADC input will be floating, meaning that the value of the indicator can assume any value.

The only way to bring the signal back to zero after the signal source is disconnected, is to physically connect the input channel to the ground.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments
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I´m using LabVIEW 8.0 with Real Time 8.0 and a Desktop PCs as RT Target.
 
In the host.vi, I have a Waveform Chart, and a cluster with four double controls to pass the values of the Frequency, Offset and Amplitude. I have created with the cluster a custom shared variable.
 
In the traget I have within a Timed Loop the Simulated Signal.vi and a Shared variable, double one. I have selected both shared variables to be Network-Published, and the period of the Time Loop is 1 ms.
 
I intend to be able to change the senoidal waveform´s amplitude and frequency while running, but I don´t get any value. I have reproduced the vi to run just under the LabView in local mode, without the RT target, and it works fine, although I can not get the frequency to mach the time...  
 
Any idea why my system does not work.
 
Simbani     
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Simbani,

You say you are using a PC as a RT target -- are you using RTX? Does the respective target have the shared variable engine installed on it? Can you confirm the timed loops are running by wiring indicators to the iteration terminal?  How about wiring the error clusters of the shared variables to indicators or error handlers to observe if you are receiving errors there? These are all steps that will provide us a better idea of what is going on.

--Paul
--------------
Applications Engineering
National Instruments, Inc
http://www.ni.com/support

--Paul Mandeltort
Automotive and Industrial Communications Product Marketing
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Paul,

The reason why the custom shared variable did not pass the values from the host to the target, it was because, after I have created it, I did not deploy it.

Solution :

Click the right buttom of the mouse while pointing at the variable library in the Project and the click on Deploy All, so that all shared variables are activated.

It is good to check if the variables are all deployed and for this you can use Tool --> Shared variable ---> Variable Manager

Regards

Simbani

 

 

 

 

 

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