How to enter the phase of a signal and get in return its corresponding voltage?

[marylydie]

Hello everybody!

I am back with another pb. I am sinking of a way of sending data out of LabView to an Electronic board. Precisely, the VOlTAGE ASSOCIATED in my V.I are the data i am talking about. In order to do that, i am planning to use a 25 Parallel Port.

Can someone please help me out with ways of doing it. I will very much appreciate your contribution.

Thanx

[RavensFan]

Can you explain a little more clearly how you are planning to use a 25 pin parallel port to send out a voltage?

While it is possible to use some of the parallel port lines to send out digital outputs, (or read digital inputs), they are only going to be either zero or some voltage.  And probably not even 15V.

You will need to use an analog output to put out a voltage that varies between 0 and 15V.    What kind of current does it need to supply?  I think at 15V, you will have a challenge finding an analog output card.  You may even need to look at some sort of external programmable power supply module.

[marylydie]

Well i was hoping that by programming i could send data to the parallel port and then read it. My currrent is about 10 A.

I could not find a card working at 15 V. Then if i use a Programmable Power supply, do i gonna need LabView to program it?

This is a school project and i am worried about the cost... My goal is to send these voltages to digital potentiometers situated in a phased array antenna. That why the voltages are a bit high.

Please help me

[smercurio_fc]

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@marylydie wrote:

My currrent is about 10 A.

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10 Amps?!?!  Are you sure you don't have a decimal point in the wrong place?

[marylydie]

This is the amount of current in my phase shifters not in my  elctronic board.. That is why i  planned to construct one and put somme buffer. The board is suppose to be the link between LabView and the antenna.

If i think of sending these voltage digitally, still not possible?

[marylydie]

10 mA. :womansurprised:Forgot the m

[smercurio_fc]

You will not be able to use the parallel port to source/sink that much current. The parallel port is not designed to handle that much current. You'll simply fry the port. You will need to use an external card.  There are cards that can go up to 15V. They usually work through a DC-DC converter or some sort of external voltage feed. NI has several that operate at 24V, though I'm not sure if the output voltage is programmable. You should contact your local NI sales rep. You can always use an external programmable power supply as well.

Side-comment about the VI that you had posted: The wiring of the constant of "4" is not necessary. You are autoindexing the for-loop so it knows how many times to run based on the number of elements in the array. It's also better to generate the X and Y arrays and then feed them to the graph outside the loop rather than continuously calling the Build XY Array function each time.

[marylydie]

Hello, thanx for your advices, it will not be wasted.

I have a question, what if  i normalise my values, convert them to binary number and them send them to a DAC operating at 700uA via those port? Can it work?

[smercurio_fc]

700 microAmps is not the same as 10 milliAmps. You may want to consider speaking to someone with electrical engineering or electronics experience.

[marylydie]

Hi everybody!!

Back again with a little problem. Remember my application where i had to enter an angle and display the corresponding voltage? Well my scope has changed a bit since then. I have to calculate a certain angle beta, and display a  Phase distribution has Indicator. All the calculation has been done in Matlab. When running the VI Labview says that i have; seems like Labview does not like the fact that i declare an `` undefine input ``.

Don`t know how to fix it...