xy plot 2 voltages

[lav21]

Hey...

I need to plot 2 voltages. Basically i have 2 input voltages ranging from -1 to 1 (both), so i need the center of the plot to be (0,0) and to basically show the postion on the plot (xy plot??? - i tried but could get it to do this)

|------------------------------|

|                                      |

|                         x x        |

|                      x      x      |

|                                x    |

|                                      |

|___________________|

Basically i need to display the center of pressure on a plot & keep the last ~5seconds of the data displyaled at all times.

I really appreciate any help

Thanks in advance

Matt

[lav21]

oh .. by the way... i am using the LabVIEW 8 & the NI DAQ

thanks again

[smercurio_fc]

This is a fairly simple problem. You can do this with either a chart, or a graph, with the latter being either a regular or XY. You said you tried but could not get it to do it. What have you tried? Have you taken a look at the graphing examples that come with LabVIEW?

[lav21]

Well i tried to connect as the example suggests: Build XY Graph -> XY Graph.

My inputs are: Data type Waveform (DBL) - coming from the DAQ (DAQ Assistant). I also tried to convert the Waveform TO Dynamic Data type (as the example has it), but nothing happens (nothing shows on the screen.

The inputs range from -1 to 1 (I am monitoring the inputs).

I also tried to simulate the inputs with a slider input (+ convert to dynamic data). Runs but nothig shows on the graph (same as when the inputs are from the daq).

Thanks again for your help

[Dennis_Knutson]

You probably need to post your code. Are you sampling multiple points from the DAQ Assistant or only one at a time? If it's one at a time, then a graph will not show anything except a single point. You need to use a chart in that case.

[lav21]

Hey ..

yes i am sampling multiple points (channels???) from the DAQ Assistant.

Here is my code ... and all I want to plot is the position basically of the 2 inputs (range -1<x<1 for both) with the (0,0) in the center and dislplay the last "little bit of data" - few seconds.

I appreciate all the help... cheers

[Dennis_Knutson]

Here's your VI cleaned up. I really don't like the express VIs and dynamic data but if you are going to use the express functions, you might as well keep the dynamic data intact as much as possible. Could you run this and if you continue to have problems, save the VI with some actual data and repost it? You do this by running it and then stop it. Go to the Edit menu and select Make Current Values Default. Save the VI. When you post it, then someone can look at what is going on without having any hardware.

Message Edited by Dennis Knutson on 04-05-2008 11:49 AM

[lav21]

Works great!!!
Thank you, thank you, thank you!!!

ill get the hang of all the .vi's eventually

Thanks again Dennis