range selection using the NI 4351 example "435x fast.vi" in LabView 2009.

[Toad.]

I am using the NI 4351 DAQ board and the example "435x fast.vi" in LabView 2009. I wanted to add a range function and have the scale labels reflect the proper values. How can I programmatically change the Minimum and Maximum parameter values for the "Y" Axis of the “Scaled Data" Waveform chart properties.

[Chris-G · Accepted solution]

You can programmatically change the Y axis range as well as many other properties of the waveform chart using a property node. If you are not familiar with property nodes, you can create one for the chart by right clicking the chart in the block diagram and selecting to create a property node. From there you can select what property you would like to change. For your specific question, right click the chart and select Create > Property Node > Y Scale > Range > Minimum/Maximum. Once you create the property node, you'll have to specify that you want to modify properties by right clicking it and selecting "Change all to Write." Each of the properties can then by controlled using a control or constant.

I've attached a basic example (in LV 8.6, let me know if you need older) that modifies the Y axis range of a waveform chart using two controls on the front panel. Note that I have a third property, YScale.ScaleFit, set as 0 by a constant. This programmatically turns off autoscaling on the chart. Autoscaling must be turned off if you want to manually scale an axis. Alternatively you can just turn autoscaling off from the front panel by right clicking the chart.

Hopefully this helps.

Chris G

[Toad.]

Getting a little slow in my old age. Discovered the Property nodes after an extended nap and another look at the help files. Thanks for all yor effort!

I've come upon another problem with my range selection. Give me a day or two to try and work it out.... I'll be back. 

Toad