Virtual channels with 6602 counters

Can I define 6602 counter source and gate inputs as virtual channels with MAX 2.1?

Hello;
You can't do that with MAX at this time yet.
Filipe

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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.

Single virtual channel with multiple digital ports

Hi all,
I have created a program that creates a task to read continuously from 3 digital port lines from the same device (PXI-6133). I am trying to figure out how I can retrieve the data from each port line to put into a waveform graph. Currently, I am using the DAQmx Read instance with "1 Channel N Samples" but I get a waveform with all values at the same time or a waveform graph with all three lines transposed.
I am using Windows XP and LabVIEW 8.6.
Appreciate any help!
Solved!
Go to Solution.

Hi Matt,
Thanks for your reply. Unfortunately thats not quite I am looking for. I am sending the DAQmx task the 3 port lines that I want therefore as I have read it bundles them all into one channel by default. What I want to do is take that one channel and parse out the data of each of the 3 port lines to create 3 new waveforms to work with individually.
After fumbling around a little bit, I was able to sort of get what I wanted. I've attached a screen shot of that portion of the program. The red circle in the bottom right hand corner is how I want to end up. I only did it for one of the pieces of data just to try it out and the conversion to string is just for me to print out what I'm working with. Unfortunately, when I look at the waveform it seems like maybe some extra 0's are being thrown in because its not the same graph that appears from the beginning (when all 3 pieces of data are transposed on each other). Let me know what you think.
Thanks,
julissa
Attachments:
LabVIEW-ss1.JPG ‏57 KB

Duplicate physical channel with virtual channel

I accidently created more than global virtual channel with one physical channel, for example:
physical channel global virtual channel
a0                       vtc00
a0                       vtc01
a0                       vtc02
My questions are:
1-How do I change the virtual channel as the following:
physical channel global virtual channel
a0                       vtc00
a1                       vtc01
a2                       vtc02
2-How do I re-name/delete the global virtual channel, when it's not in the task?
Thanks you for your time, Dylan
Solved!
Go to Solution.

Thanks you Carisa for fast response, but that not the right answer I am looking for.
May be I did not make myself clear. I attached two screenshots for example: On one screenshot, you will see bri00, bri01, bri02, bri03, bri04, bri05, bri06, bri07, bri08, bri50 on the virtual channel tab, however you won't see them display under NI-DAQmx Global Virtual Channel (second screenshot). On the second screenshot, you only see bri00, bri01, bri02, bri03, bri04, the rest of bris do not display on here like they display on the virtual channel tab.
Now I can't create the new global virtual channel under NI-DAQmx Global Virtual Channel with the name bri05, bri06, bri07, bri08, because I will get the conflict name error pop up on the screen. How can I delete those bris in the virtual channel tab?
Thanks again for your time, Dylan
Attachments:
virtual-1.png ‏45 KB
virtual-2.png ‏226 KB

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

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.

DAQmX create virtual channel execution time

Hi,
I am using DAQmX Create Virtual Channel for 70 different Digital Output. It took 35 seconds to execute the DAQmX Create Viryual Channel VI.
What are the steps to make the execution faster.
Valliappan.M

Have you tried creating a global virtual channel with MAX?
André
Regards,
André
Using whatever version of LV the customer requires. (LV5.1-LV2012) (www.carya.nl)

Why is the input mode greyed out when I try to create a virtual channel for my 1102?

I have set up a virtual channel for my SCXI-1102, and the input mode is greyed out with it set to "differential". I have already skimmed this forum for answers, and I have checked to verify that the mode slot under the AI tab for my MIO-E series card is set to nonreferenced single-ended mode. I then created a virtual channel with the device slot under the hardware column set to Dev1_SC1_MD1CXI-1102. At this point, as already stated, the input mode goes grey while set to differential. What's going on?

Hello,
All outputs from the SCXI module are measured in differential mode. You can still mix differential and single ended measurements (if you use the remaining channels of your daq board).
The easiest way to mix modes is with virtual channels. All SCXI analog input channels will be differential, while you can make other virtual channels differential or single ended. If you don't want to use virtual channels, you can use AI Hardware Config in LabVIEW to change the mode.
Hope this helps. Regards,
John N
Applications Engineer
National Instruments

Troubles with virtual channels

I programm my applications on an PC without any NI-Hardware. My problem ist, that I need virtual channels from the Measurement&Automation-Explorer.
My first attempt was, to configure some channels without settings for hardware. Normally when I use an DAQ-Constant in my application, I could select the configured channels. In this case I couldn´t.
My second attempt was, to use two PCI-DIO96 cards. I configured also some channels, but I get the same result. I couldn´t select the configured channels in LabView(6.1)
Did I need the complete extern hardware, or is there another reason for my problem?
Best regards
Robert

Robert;
Virtual Channels only make sense when used in conjunction with a DAQ device. If you don't have a DAQ device, Labview won't recognize that Virtual Channel as a valid one.
Regarding the PCI-DIO96 boards, make sure you installed those properly, before creating the Virtual Channels for it. If they are not installed, you will fall into the same issue as if you don't have a DAQ device on the machine.
Regards
Filipe A.
Applications Engineer
National Instruments

NI 6602 buffered pulse width and buffered period measurement with 2 counters synchronized

I modify the example buffered event counting with 8 counters for use with 2.I obtain error 10600 or 10455 and never the waited values.Can you give me a VI example . Thank you for your help

What changes did you make to the VI? If you attached the altered example I could take a look at it. The example program for using 8 counters performs some configuration that you won't need for just two counters. For instance, if you just want to use counters 0 and 1, you won't need to perform pad synchronization.
I've altered the program to use with two counters and attached it to this response. Hopefully this will work for you.
Regards,
Todd D.
NI Applications Engineer
Attachments:
Buffered_Event_Counting_(2).vi ‏126 KB

Drive Redirection virtual channel hangs when copying a file from server to client over RDP 8.1

Problem Summary:
A UTF-8 without BOM Web RoE XML file output from a line of business application will not drag and drop copy nor copy/paste from a Server 2012 R2 RD Session Host running RD Gateway to a Windows 7 Remote Desktop client over an RDP 8.1 connection and the Drive
Redirection virtual channel hangs. The same issue affects a test client/server with only Remote Desktop enabled on the server.
Other files copy with no issue. See below for more info.
Environment:
Server 2012 R2 Standard v6.3.9600 Build 9600
the production server runs RDS Session Host and RD Gateway roles (on the same server). BUT,
the issue can be reproduced on a test machine running this OS with simply Remote Desktop enabled for Remote Administration
Windows 7 Pro w SP1v6.1.7601 SP1 Build 7601 running updates to support RDP 8.1
More Information:
-the file is a UTF-8 w/o BOM (Byte Order Marker) file containing XML data and has a .BLK extension. It is a Web Record of Employment (RoE) data file exported from the Maestro accounting application.
-the XML file that does not copy does successfully validate against CRA's validation XML Schema for Web RoE files
-Video redirection is NOT AFFECTED and continues to work
-the Drive Redirection virtual channel can be re-established by disconnecting/reconnecting
-when the copy fails, a file is created on the client and is a similar size to the original. However, the contents are incomplete. The file appears blank but CTRL-A shows whitespace
-we can copy the contents into a file created with Notepad and then that file, which used to copy, will then NOT copy
-the issue affects another Server 2012 R2 test installation, not just the production server
-it also affects other client Win7 Pro systems against affected server
-the issue is uni-directional i.e. copy fails server to client but succeeds client to server
-I don't notice any event log entries at the time I attempt to copy the file.
What DOES WORK
-downgrading to RDP 7.1 on the client WORKS
-modifying the file > 2 characters -- either changing existing characters or adding characters (CRLFs) WORKS
-compressing the file WORKS e.g. to a ZIP file
-copying OTHER files of smaller, same, and larger sizes WORKS
What DOES NOT WORK?
-changing the name and/or extension does not work
-copying and pasting affected content into a text file that used to have different content and did copy before, then does not work
-Disabling SMB3 and SMB2 does not work
-modifying TCP auto-tuning does not work
-disabling WinFW on both client and server does not work
As noted above, if I modify the affected file to sanitize it's contents, it will work, so it's not much help. I'm going to try to get a sample file exported that I can upload since I can't give you the original.
Your help is greatly appreciated!
Thanks.
Kevin

Hi Dharmesh,
Thanks for your reply!
The issue does seem to affect multiple users. I'm not fully clear on whether it's multiple users and the same employee's file, but I suspect so.
The issue happens with a specific XML file and I've since determined that it seems to affect the exported RoE XML file for one employee (record?) in the software. Other employees appear to work.
The biggest issue is that there's limited support from the vendor in this scenario. Their app is supported on 2012 R2 RDS.
What I can't quite wrap my head around are
why does it work in RDP 7.1 but not 8.1? What differences between the two for drive redirection would have it work in 7.1 and not 8.1?
when I examine the affected file, it really doesn't appear any different than one that works. I used Notepad++ and it shows the encoding as the same and there doesn't appear to be any invalid characters in the affected file. I wondered
if there was some string of characters that was being misinterpreted by RDP or some other operation and blocked somehow but besides having disabled AV and firewall software on both ends, I'm not sure what else I could change to test that further
Since it seems to affect only the one employee's XML file AND since modifying that file to change details in order to post it online would then make that file able to be copied, it seems I won't be able to post a sample. Too bad.
Kevin

Is it possible to display in a front panel indicator the units name (for instance, N "Newtons" or ºC) from a virtual channel that you previously defined using MAX?

If possible, how can I do it?
Thanks in advance With LabVIEW 6 it is clear that we can display the DAQ channel name of previously defined virtual channels, so it seems to be possible that we would be able to access to other information defined in MAX as channel units name...
Thanks

Yes it is possible.
Locate the LLB:
LV folder\vi.lib\daq\dqchnutl.llb
There you find useful vis to handle virtual channel.
The Get DAQ ChannelNames.vi return also the channel units

Errors in Creating Virtual Channel

I am creating a IVI switch driver. The driver passes the IVI Specific Driver Suite 2.2 and IVI Switch SFP testing. When I try to create the virtual channel the device is found (created IVI Logical Name and other fileds) but the channels displayed are empty on the Channels/Exclusion tab. What calls are made when creating the virtual channel? I want to create a CVI or TestStand program to simulate the sequence that Switch Executive performs.
When validating a configuration, are all possible channels used in SetPath loop? As an example, if three channels are defined (Front, rear, & base) but only the front->base, rear->base, base->front and base->rear are valid configurations. Will the vaildate try a front->rear configuration? Will a disconnect call be placed in between each SetPath call?
Thanks.
Randy

Randy,
Although you cannot step through the NISE engine, you can step through your driver's code and debug its behavior. If you have problems with importing IVI virtual name into switch executive virtual device, then what you need to do is select nimax.exe as the process to debug and run it with the debug version of your driver. If you were using CVI, you can set the external process under Run>>Select External Process. If you're using MSVC, you can choose "open project" and browse to nimax.exe and then add symbols for your driver DLL in the project settings.
The entry points to monitor (for your particular problem) are the ones that deal with getting the number of channels and getting individual channel names and their attributes. Make sure that your driver returns the correct number of channels and that it also returns all these channel names correctly. If you see no error in switch executive (I.e. it just says OK after you import your ivi logical name), then my guess is that your driver returns 0 for the number of channels.
Please be aware that switch executive exercises much more than any of the IVI clients you mentioned. Yet it does not go "through the back door" for anything, it (obviously) uses public entry points in the driver to perform what it needs to do.
So, you can start by setting up debug project in your favourite environment, and check the behavior of the following functions in your driver:
getting the IVISWTCH_ATTR_CHANNEL_COUNT attribute
IviSwtch_GetChannelName (with your prefix, of course)
and see if those work. My guess is that something is not working correctly between these two functions.
Let me know
-Serge
Srdan Zirojevic

How can I get properties of global virtual channels using DAQmx?

I'm using DAQmx with VB6. In my app, I would like to be able to present the user with a list of available predefined channels to select from. I can use DAQmxGetSysGlobalChans to get a list of the channels, but I need a way to sort out which of these channels are defined as inputs, and which are outputs. It would also be nice to be able to query other properties of the virtual channel (for example, the device and physical channel being used). These all seem very simple things, but I haven't found anything like this in the documentation so far.
Thanks.

Try using DAQmxGetChanType(TaskHandle taskHandle, const char channel[ ], int32 *data)DAQmxGetChanType(TaskHandle taskHandle, const char channel[ ], int32 *data). This will return one of the following types:
DAQmx_Val_AI
10100
Analog input channel.
DAQmx_Val_AO
10102
Analog output channel.
DAQmx_Val_DI
10151
Digital input channel.
DAQmx_Val_DO
10153
Digital output channel.
DAQmx_Val_CI
10131
Counter input channel.
DAQmx_Val_CO
10132
Counter output channel.
Let me know if this works.
Regards,
L. Allen

Duplicating a CTR Global Virtual Channel in MAX does not update the CO.Pulse.Term setting

Hi,
Here is the issue description:
MAX version: 4.6.2f1
daqmx: 9.0.2
Hardware: cDAQ-9178 , NI-9474 Digital output.
For this module one has:
crt 0 out <--> PFI3
ctr 1 out <--> PFI7
crt 2 out <--> PFI1
ctr 3 out <--> PFI5
1. In MAX create a Global Virtual Channel as a CTR output on ctr0.
2. use the Duplicate in the menu to create a second counter output. Change its name, and change it ctr output to ctr 1 OUT.
3. In MAX, the Pulse Output Setup pane should reflect the change by showing the ouput terminal pointing to the proper PFIi
4. Export the settings to an INI file, and look at the CO.Pulse.Term settings for both CTR channels: they will both appear with the SAME PFIi !
5. Using LabVIEW Write a vi that generate pulses on these 2 channels , you will get Error -89137 saying a PFIi resource is already used. If you look at the Task property CO.Pulse.Terminal, it returns the same for both tas, which is the same error seen in the ini file.
Can someone at NI check this? Thx.
Laurent
PS: I posted this message in the LabVIEW board as I did not find one for MAX
Solved!
Go to Solution.

Hi Laurent,
I verified this behavior with DAQmx 9.1 and a simulated device. I will file this as a Corrective Action Request (CAR). Creating the channels manually works correctly and produces the correct .ini file. Sorry for any inconvenience this may cause.
Regards,
h_baker
National Instruments
Applications Engineer
Digital Multimeter Resources

Virtual channels with 6602 counters

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