DAQ - change scale in real time

[san_gr]

Hi,

I'm not sure if the title is accurate. I have a vi where I have a DAQ assistant to monitor two analog channels and display them on a graph. I want to have a switch for each channel to be able to invert the corresponding graph.

The way I tried to do it is create a custom scale in the DAQ assistant with the slope set to -1 and then using a "DAQmx channel" property node to change the "AI: custom scale name" property accordingly. Well I ran into 2 problems:

1. I couldn't figure out how to change a specific channel. Instead it says that if you don't specify a channel it will change all of them.

2. When I run the vi I get an error for the property node that says "Specified property cannot be set while the task is running." But I need to be able to change it while running.

So.... HELP!

[MartinMcD]

Hiya,

I know the problem you mean and if there is a better way around it than my hack I would love to know it. My options are:

- Don't use the custom scale property and just scale my raw (eg voltage) data manually when I read it in

- Use the custom scale property and to change the scale (eg zero a pressure reading) stop and restart the task.

Thanks,

Martin

[san_gr]

Well I did the project again from the beginning but this time I didn't use the DAQ assistant, instead I set it all manually. Then I stripped the data into channels and unraveled each channel and then with a switch I invert the data. After that I recombine everything and have it displayed on a graph.

This way it works just fine!

PS. Since English is not my native language, pardon any mistakes in the terminology

Edited January 15, 2010 by san_gr