Order of channels in Analog 2D DBL NChan NSamp VI

[souperman1985]

The help file for the "Analog 2D DBL NChan NSamp" VI says that we can control the order of the vectors in the 2D double which it creates by two ways:

1) the order in which the channels are added to the task

2) something called the "Channels To Read" property.

I understand the first one, I think, and I can order channels as I wish this way.  However, I would prefer to use the second option, so that if somehow the wiring of the channels gets mixed up, I can still have the channels in the order I prefer.  

Can someone help me figure out how to do this please?

thanks!

[[dk]]

The second option is referring to a property node, and more specifically the DAQmx Read Property Node. This property node can be found in the Functions Palette » Measurement I/O » NI-DAQmx » Read Node, or by simply using quick drop (ctrl + space) and searching for "DAQmx Read Property Node". Once you've placed the property node on the block diagram, you can change the property from "RelativeTo" to "ChannelsToRead" by clicking on the text. You can then use the input to the ChannelsToRead property to specify the order of the channels in the array. Hope this helps!

[souperman1985]

Hi Daniel,

thanks for your reply and help.  I have wired up what I think you mean (see image below).  I am assuming that the order of the "ChannelsToRead" listed top-to-bottom in the DAQmx Read Property Node is the order in which they will be added to the array (first the top; last the bottom).  Is this what you had in mind?

thanks,

Matt 

[[dk] · Accepted solution]

Somewhat. The 'Channels To Read' property actually accepts a DAQmx Global Channel data type, while you have a DAQmx Task Name data type. So the correct way to utilize the DAQmx Read property node is to just creat a constant or control from the 'ChannelsToRead' property and entering in the order of the channels you would like. I have provide a VI snippet to help illustrate:

 

[souperman1985]

Thanks again Daniel!