How a dvm works..Could some one explain that to me in fairly detailed terms...thanks

[Genimale]

Hello,

I am looking to create a basic DVM with the NI USB-6008.  All I need todo is read a Digital voltage of ~1V continuously and display it in a text box in VB.  I have looked at the NI-DAQmx Digital input example code but does not show how to convert the input data into a visual text.  I have limited experience with VB and was wondering if anyone has a simple code that can do this.

Thank You

Aaron 

[JasonWhite]

I think that what you need is analog input and not digital input.  Analog input is used to access the digitized signal coming back from the A/D converters on your DAQ device.  Digital input, on the other hand, is used to read from the digital I/O lines (ie. bits).

You essentially need to do 3 things:

1.  Call the appropriate DAQmx Create Channel function to set up the analog input.

2.  Call the appropriate DAQmx Read function to read back your floating point voltage.

3.  Set the value onto the text box (for example, Text1.Text = CStr( myReading )  )

You can then repeat steps 2 and 3 in a loop.

Hope that helps.  You might also be able to find some examples of how to do this either installed with the driver or online.

[tryingtounderstand]

hey I wander if someone could help me out and explain how a dvm actually works...right from the leads to the digital readout....that would be fantastic...

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@JasonWhite wrote:

I think that what you need is analog input and not digital input.  Analog input is used to access the digitized signal coming back from the A/D converters on your DAQ device.  Digital input, on the other hand, is used to read from the digital I/O lines (ie. bits).

You essentially need to do 3 things:

1.  Call the appropriate DAQmx Create Channel function to set up the analog input.

2.  Call the appropriate DAQmx Read function to read back your floating point voltage.

3.  Set the value onto the text box (for example, Text1.Text = CStr( myReading )  )

You can then repeat steps 2 and 3 in a loop.

Hope that helps.  You might also be able to find some examples of how to do this either installed with the driver or online.

---

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@JasonWhite wrote:

I think that what you need is analog input and not digital input.  Analog input is used to access the digitized signal coming back from the A/D converters on your DAQ device.  Digital input, on the other hand, is used to read from the digital I/O lines (ie. bits).

You essentially need to do 3 things:

1.  Call the appropriate DAQmx Create Channel function to set up the analog input.

2.  Call the appropriate DAQmx Read function to read back your floating point voltage.

3.  Set the value onto the text box (for example, Text1.Text = CStr( myReading )  )

You can then repeat steps 2 and 3 in a loop.

Hope that helps.  You might also be able to find some examples of how to do this either installed with the driver or online.

---

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@JasonWhite wrote:

I think that what you need is analog input and not digital input.  Analog input is used to access the digitized signal coming back from the A/D converters on your DAQ device.  Digital input, on the other hand, is used to read from the digital I/O lines (ie. bits).

You essentially need to do 3 things:

1.  Call the appropriate DAQmx Create Channel function to set up the analog input.

2.  Call the appropriate DAQmx Read function to read back your floating point voltage.

3.  Set the value onto the text box (for example, Text1.Text = CStr( myReading )  )

You can then repeat steps 2 and 3 in a loop.

Hope that helps.  You might also be able to find some examples of how to do this either installed with the driver or online.

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[Dennis_Knutson]

Trying,

Your Google search led you pretty far astray. You might want to start at http://en.m.wikipedia.org/wiki/Digital_voltmeter but since you don't have any electronics background, some of the concepts (i.e. analog to digital converter) are going to be incomprehensible.

[tryingtounderstand]

I do Have some understanding as I am an electrical instructor, so some help would be great!!

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@Dennis_Knutson wrote:
Trying,

Your Google search led you pretty far astray. You might want to start at http://en.m.wikipedia.org/wiki/Digital_voltmeter but since you don't have any electronics background, some of the concepts (i.e. analog to digital converter) are going to be incomprehensible.

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[tryingtounderstand]

So you have an anolog, which isactually an amp reading of the circuit with certain amount of ohms for every setting, the amps then cause a magnetic field cousing the magnetic allready existing and calabrated to the ohms setting used, causing the deflection of the volt needly to move accordingly...

So to start the digital volt reading you have an anlog reading converted to digital and then what??????

thanks for any help and the direction you have allready given me...

[Dennis_Knutson]

This is really the wrong place to be having this kind of discussion. This is a board for National Instruments hardware and software.

To provide a quick answer, you pass a voltage into an attenuator/amplifier. This scales the voltage into the range of the a/d. The digital output of the a/d is passed to display unit that converts the digital into something readable. Many variations on this.

[tryingtounderstand]

Where is a better location that this conversation should take place? And thanks for the help so far...