Scale Type of DAQ virtual channels configured using MAX

I configured some analogue input and output channels using Measurement & Automation Explorer, under Data Neighborhood. One of the attributes I could change is called "Scale Type". I'm wondering what it's for, or where I can find information about it. Thanks

Amyz,
The most helpful document I found was the DAQ Channel Wizard Tutorial: http://www.ni.com/support/labview/toolkits/chanwiz/. Step 7 of analog input or output briefly describe the scale modes. Good luck with your application.

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Is There a way to programmatically extract global virtual channel info from max?

I have a group of DAQmx virtual global channels setup in MAX and I would like to be able to programmatically extract the physical channel information to be included with the data file. In the past I have been able to use traditional NI-DAQ channel utility vi's to accomplish this, but they only see traditional NI-DAQ virtual channels and not DAQmx virtual channels. Is there a group of vi's for extracting DAQmx virtual channel information? I'm using Labview 7.1 with a Windows XP OS.

Paul,
I can access basic properties using the approach you described, but do you know how to get the units from the global virtual channel? Say I had a general appliance for reading in load cells, and I wanted to have the axis labels in a graph show the units of whatever load cell had been selected.

Is CJC compensation automatically applied to Virtual Channels created with MAX?

I have a SCXI 1000 chassis, a SCXI 1102 module and a TC 2095 terminal block. I am configuring virtual channels with the names TC(n) where n is the channel number. When I configure the virtual channel, I am selecting 'built-in' CJC. The question I have is:
When I reference the virtual channel from my DAQ application, is the data I receive already cold-junction-compensated, or do I have to read the CJC voltage as a separate channel, and apply the correction factor manually on my block diagram (like we had to do in the old days)?
I gather that the data that I read, which is obviously scaled to engineering units, is, indeed, cold-junction compensated, but I would like to be certain that t
hat is the case. Thanks.

Wes;
You are right. That is the way it works. If you specify the CJC compensation in MAX when creating a Virtual channel, to be the built in CJC, the data you get is going to be CJCed already.
Hope this helps.
Filipe

How do I import Traditional NI-DAQ Virtual Channels and MAX 3.1

I installed Labview 7.1 on a new machine and the tools option in MAX 3.1 does not have the option to import traditional NI-DAQ configurations.

If you have support for Traditional NI-DAQ installed, you should have the option to open a configuration file from: Tools>>Traditional NI-DAQ Configuration>>Set Active Configuration. You can check the installation of Traditional NI-DAQ under the Software tree in MAX.
Hope this helps.
Regards,
Erin

Writing in sensor calibration data to my virtual channels in MAX using Labview.

System consists of a few pxi6713 cards, a 6527 digital input card and some scxi cards (1520, 1104c, 1125).
Every 3months or so we run a calibration on the testing stand which uses these cards, and the sensor ranges and physical ranges listed in MAX has to be manually entered each time.
I am looking for a way to do this automatically. This may be a problem, but we are using NI-DAQ legacy (perhaps if absolutely necessary we could goto daqmx).
I have figured out howto read virtual channel information from max correctly, but I have no understanding of trying to write calibration information to the virtual channels.
Any help is greatly appreciated!
Thank you!
jacob

Hi mak90,
There are no ways to change the sensor range and physical ranges
programmatically in Traditional DAQ. Under DAQmx, you have Scaling VIs,
Calibration VIs, Task VIs that allow you to change various settings in
MAX programmatically.
Please let us know if you have any further questions.
Best regards,
Nathan Yang
Applications Engineer
National Instruments

Use virtual channel name as input to DAQmx Write? LV8 and DAQmx

I've created a task for digital output that contains 8 named channels using the DAQmx Create Channel VI in Labview. Is it possible to use the channel name as an input to the DAQmx Write VI to reference the desired channel? I tried wiring a string with the channel name to the "task/channels in" input but I get a -200428 error that says the Value passed to the Task/Channels In control is invalid.
The help "name to assign" input for the DAQmx Create Channel VI says
If you use this input to provide your own names for the virtual channels, you must use the names when you refer to these channels
in other NI-DAQmx VIs and Property Nodes
OK, so how do you use the name assigned in other VIs?
George

George,
I think that there may be some confusion here about the difference between local and global virtual channels. First of all, please take a look at the following knowledge base:
Physical Channels, Virtual Channels, and Tasks in NI-DAQmx
As discussed in this KB, local global channels are created inside a task, and they only apply to that task. In the help file for the DAQmx Write VI, the "task/channels in" description says "if you provide a list of virtual channels, NI-DAQmx creates a task automatically." When you wire a string to this input, a new task is being created, and unless the channel name that you wire in is a global virtual channel (listed in MAX), you will get the error 200428 that you mentioned. This is because that virtual channel that you are specifying is local to another task and is not associated with this new task.
One solution to this issue is to use the DAQmx Save Global Channel VI to save your local virtual channel as a global virtual channel before calling DAQmx Write. Once this is done, you can then wire the same string constant to the "task/channels in" input of DAQmx Write or other DAQmx VI's.
The help text is still correct, but is only applicable in certain situations. For example, if you create and name an analog input local virtual channel with DAQmx Create Channel, you could then use this channel name as the source input to a DAQmx Trigger VI configured for an analog edge start trigger. You could also use that channel name as the input to the "ActiveChans" DAQmx Channel Property, which would enable you to modify the properties of that particular channel.
Hopefully this information is helpful to you.

AI Group Config Error 10001 using Virtual Channels

In my LabVIEW block diagram, I usually enter in numbers, e.g. 0,1,2 for the channel string input of AI Config. When I try to use a virtual channel, I simply type in the virtual channel, e.g. 0,K Thermocouple,2. However, this causes AI Group Config Error 10001, which applies to an invalid channel string. What is the correct way to enter a virtual channel into the channel string?

Do you have channels with virtual names of "0", and "2"?
If not you may be confusing MAX by using both naming conventions.
Try using only Virtual names.
I generally will use an array of strings where each element is the vitual channel name with no problems.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Can I programmatically change a virtual channel's scaling?

I want to be able to read and write the scaling parameters for a virtual channel. Using NIDAQ 6.8 with MAX 2.0 and LV 6.0.2.
Thanks

This question actually belongs in one of the Measurement Devices categories. In the future, please post to the appropriate forum. You will find similar questions and get exposure to others with similar interests when you post directly into one of those categories.
In answer to your question, you can read the virtual channel properties, but you cannot programmatically change them. If there were a finite number of changes, you could have multiple config files that contained the same virtual channel names. Then, you could programmatically switch which config file MAX was using.
Alternatively, you can apply the scaling in your program if you read the raw value through the virtual channel (no scale) and then pass it into a scaling function.
You can find exa
mples for saving virtual channel properties to a text file and for changing config files in the NI Developer Zone. Start at the http://www.ni.com/support page and choose Example Programs from the Technical Resources pulldown menu. Then, type in keywords, such as "virtual channel" or "change NI-DAQ configuration".
Regards,
Geneva L.
Applications Engineer
National Instruments
http://www.ni.com/support

LabVIEW error 10899 when testing a virtual channel

I am setting up a virtual analog voltage output channel in the "Measurement and Automation Explorer". I am able to get throught that process and it shows up under "Traditional NI-DAQ Virtual Channels" on the left. When I right
click on the channel and then go to "Test", I get the message "Error - 10899 occured at AO group config".
Sometimes when clicking on test, the MAX crashes and a random window from LabVIEW pops up on the screen. Then I
have to open the MAX again.

Hello bberma01,
I don't like to give you this type of answer, but in this case I think the best think to do is to unistall and reinstall your driver. While we are at it, DAQmx is the newest driver and is very user friendly. I would suggest using it for your data acquisition development.
If you need to download the driver, you can find it Here

Virtual Channel with RT system

I have configured many virtual channel on a RT system with the "Remote DAQ configuration" menu from MAX (I am not sure of the menu name because I am using the french version).
Now I would copy all these virtual channel on the host system as virtual channel on a remote device. Is there a way to do this automaticaly ?
If I try to create manually the virtual channel for the remote device, there is too a new virtual channel in the Remote DAQ configuration. As I want to use the same name for the remote device and for the remote DAQ configuration, I have 2 virtual channel with the same name in the remote DAQ configuration.
A solution will be to suppress all the virtual channel from the remote DAQ configuration and to recreate the virtual
channel on remote device from the "My System" folder. But in this case I will lose my work (I have more than 100 virtual channel).
Thanks for your help

Yes, I would have the same virtual channel configuration on the Windows machine as on the remote RT Engine.
With the virtual channel configuration on the Windows machine, I can use the "Test" button (from MAX) which is an easy and very quick way to verify that the channel is working.
In fact, as you mentionned in your answer, I just need to create a RDA device in the "Device and Interface" folder, and automatically all the virtual channels configured on this remote device are "imported" under the "Data Neigborhood" folder.
I didn't see this functionnality in my first test because I had created the Remote Device entry before I created the virtual channel on this device.

How can I get an invidivual Virtual Channel name without having to pick through an array of all channels?

I see "Get DAQ Channel Names.VI" and "Get Channel Information.VI" but I just want to get the name of just channel 0, or just channel 1. Is using an array of all channel names the only way I can do this?
I have Labview 6.1.
THANKS!!!
Lauren

Lauren,
Yes, currently that is the best way to go about accomplishing that. I attached a little VI that demonstrates a very basic way of finding the first virtual channel that uses device channel 1.
Ames
Applications Engineering
National Instruments
Attachments:
Find_First_Channel_1_Virtual_Channel_Name.vi ‏27 KB

How to get channel information using RDA

I'm attempting to build my VIs in such a way that I have the user only supply the channel names while trying to get the device number using "Get Channel Information.vi". I found the "Virtual Channel Configurator.vi" on this site, which is fairly close to what I wanted.
However there is one problem, I can't get Get Channel Information to work using RDA channels (error -10003). Is there a reason, or better, a solution for this?

Dear Justin,
I am having a similar problem as in this thread, I am sending a screen
shot of the program I am using. I am using LabView 8, NI
DAQmx 8, PXI-6259 Meries card. It is a real time remote system and not
connected to my computer on which I am making the programs.
I want the pulses to appear on the output terminal that I choose, but
when I browse in the counter1(s), the global virtual channels that I
made in the remote system icon in Max do not appear?
how can I make them appear so I can send the pulse signal to that output termainal?
thanx.
Attachments:
mypic.jpg ‏2305 KB
mypic1.jpg ‏2305 KB

Can you use Virtual Channels in a Borland C++ program using the NiDAQ library? It would make configuration of my application much easier.

I have no idea which category this fits under.
Could you please CC any replies to [email protected]

This would be a question for the Multifunction DAQ section of Developer's Exchange. The answer is no, the NI-DAQ C library does not support virtual channels yet.
Best Regards,
Chris Matthews
Measurement Studio Support Manager

Computer crashes when using virtual channel custom scales.

I am using a PXI-1045, which is connected to my computer via a MXI-3, to hold 3 PXI-6115 cards as well as several other cards. I have been using virtual channels for the nine input channels I am looking at. When I added custom scaling to one of the virtual channels my LabView application crashed the next time I ran it. If I remove the scaling it goes back to working fine, but when I add it back in it crashes again. The crash causes the computer to automatically restart, but on one of the runs I got a "Fatal Internal Error: 'memory.cpp', line 593" message before the computer restarted. I've tried reinstalling MAX and updating some drivers, but nothing seems to help.
Thank you.

Still having the same problem. Ever the optimist, I submit the following info.
Error window screenshot can be found here: https://dl.dropboxusercontent.com/u/22465174/safari/safari_fail_01.JPG
Enent log entry can be found here: https://dl.dropboxusercontent.com/u/22465174/safari/safari_fail_02.txt
Version info can be found here: https://dl.dropboxusercontent.com/u/22465174/safari/safari_fail_03.JPG

Is there an easy way to document a DAQ configuration using DAQmx?

I'm looking for an equivalent to the "Virtual_Channel_Info_Grabber.vi" that was available for traditional NI-DAQ. I want to be able to create a text/XML file with all of the configuration information for a task or virtual channel. Specifically signal conditioning settings.

Mike,
Currently an example does not exist that does this in NI-DAQmx. However, you could certainly build a VI that does something very similar to the Virtual_Channel_Info_Grabber.vi in NI-DAQmx using the DAQmx System Property Node and the DAQmx Channel Property Node.
Ames
Applications Engineering
National Instruments

Scale Type of DAQ virtual channels configured using MAX

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