Set value of virtual channel

Pardon the seemingly trivial question, but how do you set a DC value of a virtual channel. The way I have it set up right now, the channel's value is unpredictable and constantly changing

Hi Justin:
If the analog input channels do not receive voltage, they will float and give unpredictable values. To get around this, you should ground the unused channels to make them read constant 0V when scanned.
For analog output channels, reset the device using the reset device VI and that will make the channels output 0V.
Penny

Similar Messages

  • 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

  • Which are the setting values for the Virtual CTI Driver? (Siebel Communica)

    hi everybody,
    the application I'm using is Siebel Communications 8.1.
    I am learning about integration processes with the Siebel Communications Server Administration Guide. One of the points or topics there is the use of the Virtual CTI to integrate your Siebel Business Applications with Oracle Contact Center Anywhere (as in the bookshelf described).
    I've read, with this driver agents can access communications functionality using the communications toolbar.
    The Virtual CTI is a driver provided by Oracle. You can't see it listed on the Administration -> Communications ----> Communications Drivers and Profiles. So I guess it is important to add this driver to the list.
    I have questions about that:
    1. Should I add this driver to the list? or when can I do that?
    2. Which are the setting values for the mentioned driver?
    - Communications Channel?
    - Inbound Yes
    - Outbound Yes
    - Interactive
    - Channel string
    - Library name
    Could anybody help me? I would appreciate that.
    Regards

    Thanks for the reply KT.
    I am not sure how to set a new custom style, but will look it up. If you have a url that points to the topic I would appreciate it.
    Thanks,
    Rhek

  • Set values for the Lock-In Amplifier's Digital Analog Converter Channel?

    If I let my user have the freedom to select whatever values they want to select in order for it to show up as the output value for the Digital Analog Channel then I cannot understand why use ibwrt(...) and ibrd(...). Because ibwrt is going to write a specific voltage at the specified channel since the manual for the Amplifier states you must input the string for writing output voltage as DAC2 3000 (the 2 signifying the channel and 3000 - the millivolts). If this hard coding occurs by using ibwrt then how can I write my code so that the user has the capability to change the voltage value and the channel to the one they want? Thanks in advance.

    Do I need a Fmt and ibwrt for both DOutput and VOutput? Because DOutput is indicative of the channels 1, 2, 3, 4 in the Lock in Amplifier and the VOutput is for the amount of volts the user can set (i.e. write to the instrument). Also I found this on the following NI website regarding filling in the value of the write buffer: Write Buffer Value. This website signifies that one must use \002 and end with 003\ which I am not sure I even need for this instance of initializing the writeBuffer[8]. Also I used [7] for the writeBuffer because I thought arrays went 0, 1, 2, 3...so on therefore writeBuffer[7] will give me space for 8 bytes? Is that an incorrect assumption? Lastly, here is my modified code according to the changes you mentioned and it still is giving me Non-Fatal Run Time Errors and not communicating. Is there anything else I am missing out on which I can't find. Seemed like I may be making this code much harder than it needs to be. Thank you for your time.
    Sincerly,
    Attachments:
    SETDAC.c ‏2 KB
    setdacwin.h ‏2 KB
    setdacwin.uir ‏3 KB

  • 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

  • Do I really need to create virtual channels in data neighborhood in order to access my pci 6034E?

    Hello all,
    This may sound a little weird, but I would like to know how to configure my 6034E without having to create virtual channels in data neighborhood. Reason being, the data is often lost when users update or search for new instruments in Measurement and Automation.
    I have tried using the AI CONFIG.VI, which gives me all the attributes I need...set channel name, device name, device channel, input mode, sensor/actuator type ect..  When I connect the AI READ.VI the value read back is incorrect. Matter of fact as an exapmle, the power supply could be off and I still read 10 Volts. But when I have created a virtual channel in data neighborhood, the data read back is correct.
    Is there another way to read back data but not have a virtual channel in the data neighborhood?
    Thanking you in advance,
    Demo

    Duplicate post

  • How do I save the virtual channel list of a task to a tab-delimi​ted text file

    I have created my data acquisition application which will save the analog inputs of the channels into columns of a text file.  Now I would like to save the names of the virtual channels in the header of the file so that couple months down the road I will have no problem of knowing which column is which.  How do I do it?
    The way I set my application up is that the task is set up in the Measurement and Automation Explorer.  In the LabVIEW program, there is an control I can pick the task I want to use, and the rest of the program will pull the necessary information based on the task chosen.
    Thanks in advance.

    Hi
    You can use a Task node located in Measurement I/O -> NiDAQmx -> Task config-->> Task node to get the devive name of the virtual channel. You can a for loop to get each individual device name and build the array of device name and analog input into one array and then write this to a text file.
    Regards,
    Nitin

  • 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

  • Why does labview forget the connections to the virtual channels in MAX?

    I create a bunch of virtual channels in MAX - some with double assignment to a single AI port.
    Context - a digital output controls a MUX to switch the inputs into the AI ports of my USB-6361(BNC) DAQmx; thereby allowing me to double up on the number of AI ports I can access (switching every 5ms).
    I can run the code without any troubles. I have now completed my hardware set up and and am now testing the integration with the code. This is where things become a little unstuck.
    Problem: some ports, over time, start displaying erroneous data that is not correct. It is not until I delete the virtual channel and re-create it in MAX, does everything settle and work. This 'bad' data is seen in the MAX test panels tab and virtual channels tab.
    What is going on - should I bite the bullet and program all port assignments (channels) within my code?
    Am i mistakenly killing a link between MAX and the DAQmx?

    natashw already told you that it's expected behaviour when you leave the analog input open. There are two aspects to this:
    1) The analog input amplifier is a high impedance operation amplifier. It's minimal stray capacitance is high enough that it gets charged through very small leakage currents in the amplifier input stage, but the high input impedance doesn't allow those capacitance to discharge quick enough to stay at a defined voltage. So your input is usually very slowly floating to one of the power supply rails depending what transistor side has a slightly higher leakage.
    2) You only have one analog to digital converter. To get multiple channels there is a multiplexer than connects the different input channels to this single ADC. When the multiplexer switches between from a connected signal to an unconnected signal those stray capacitance at the ADC amplifier input has been charged to a certain voltage from the connected channel. With only the internal impedance of the amplifier to discharge this capacitance after the multiplexer switched to an unconnected input, the ADC will simply see the voltage that the stray capacitance has been charged to.
    Having a low impedance amplifier input would solve that problem but create many more problems that would affect the measurement accuracy significantly.
    Rolf Kalbermatter
    CIT Engineering Netherlands
    a division of Test & Measurement Solutions

  • 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 Table (Logic Channel Number) in DCM9900

    Hello everybody,
    I would like to configure the DCM9900 (v. 10.0.02) in order to arrange the position where every channel will be tuned in our STB customers. I've read the manual and it seems that VCT (or LCN in some networks / literature) is not compatible under the DVB standard.
    Is there any way to configure VCT / LCN in DCM9900? Why is it compatible/configurable under ATSC and not in DVB networks?
    (Cable)VCT is very useful for TV network operators as we can configure the position of every TV channel tuned in the customer Set Top Box.
    Could someone gime me some help ? Maybe it's necessary to have ROSA system installed to configure DCM (don't have it).
    Best regards,
    Inaki
    Virtual Channel Table (VCT)
    The CVCT (Cable VCT) and TVCT (Terrestrial VCT) provide information for all virtual channels in a transport stream like: major and minor channel numbers, short channel name, and information for navigation and tuning.

    You don't need to call this function, but your specific driver does. That function is a utility function provided by the IVI engine that allows the specific driver to register all of it's channels with the engine. The engine can then use this information to track per-channel attributes, etc. All of this should happen behind the scenes. You only need to be concerned with it unless you are actually developing a specific driver yourself.
    This is different from the virtual channel name mapping in MAX. That mapping allows you to create aliased names for pre-existing channels. In your case, the IVI engine doesn't think that you have any channels (because apparently none were registered).
    You might try using a different specific driver temporarily just to ma
    ke sure that everything else is working as you'd expect.

  • Calling A Single Value From A Channel To Output To A Table Need Help

    I have populated a table that contains every value in every channel of my data set. I am now attempting to do channel calculations in order to come up with weighted averages and an overall average for the days worth of test. This data will be outputted to a new table called 'Total Table'. This Total Table is to only have one value per channel.
    The issue I am running into is 2-fold. When doing channel arithmetic, primarily Channel Sums using 'ChnSum' DIAdem does not truncate the entire data set into a new data set. It retains all the values and appends the last block with the sum of the entire channel set. I need to either be able to pull that last value dynamically (as not all my data sets are of equal length) or I need to generate a new channel that only has the sum value. Is there a way to do this?
    Here is what I have been attempting to do but to little avail. Attached is a screenshot of what the table output looks like after this code is processed.
    'Populate Total Table With Values From Above Calculations
    For j = 1 to selectData.MultiSelection.Count
    Counter = Counter + 1
    length = ChnPropValGet("[" & selectData.MultiSelection(j).Index & "]/Cumulative Fuel Used", "Length")
        If Counter = 2 Then
       [ A Bunch Of Channel Calculations That Output New Channels ]
       Call View.Sheets("Total Table").Areas("Area : " & Counter).DisplayObj.Columns.Add(ChnFind("Ch("& selectData.MultiSelection(j).Index &") > 0 " , length - 1))
      End If
    Next
    Any help would be much appreciated.
    Thanks,
    ~Nate
    Solved!
    Go to Solution.
    Attachments:
    TotalTable.JPG ‏212 KB

    This is my latest version of the code and it sort of works but its referencing my "Fan Speed" channel for some reason rather than my "Cumulative Fuel Used" channel. Im a little stumped
    For j = 1 to selectData.MultiSelection.Count
    Counter = Counter + 1
    length = ChnPropValGet("[" & selectData.MultiSelection(j).Index & "]/**bleep** Fuel Used", "length")
    If Counter = 2 Then
    Call View.Sheets("Total Table").Areas("Area : " & Counter).DisplayObj.Columns.Add(Data.Root.ChannelGroups("[" & selectData.MultiSelection(j).Index & "]").Channels("**bleep** Fuel Used").Values(length))
    End If
    Thanks,
    ~Nate

  • Daqmx Create Virtual channel timeout

    Why almost a minute and a half to get an error message from daqMX Create Virtual channel VI.
    I need to find a way to have my executable bleep immediately if the underlying drivers are not installed.
    For example, I have LV at home and supposedly have the drivers installed too but no hardware connected.
    Sometimes I run a that uses daq, however when it encounter Creat Virtual Channel VI it appears to hang for a minute and a half before finally giving an error.
    Anyone else been there, done that?
    Thanks

    Thanks for replying D-cubed.
    Actually Im calling create virtual channel in a state machine to set up the data acquisition.
    When using on a machine that has a daq device installed its a piece of cake.  no sweat.
    However, when I am at home I have LabVIEW but possibly either no daq drivers or no daq hardware.
    I believe it may be the second case since I can place a task on the BD so, I will assume the drivers are installed correctly.
    There is just no daq hardware in the system.
    WHen the create virtual channels Vi is called the PC appear to hang because that VI is executing internally (looking for a device I presume).
    The timeout takes 1.5 mins and if not for me waiting the PC would appear to be hung up.
    Finally some 'Mig error' message appear contact Ni about and so on.
    WHat I am trying to do is have my program error out immediately instead of 1.5 mins later that there is no Daq device in the system.
    Thanks again

  • What does DAQmx Create Virtual Channel (TEDS AI Accelerometer) actually do?

    Hi all,
    I have a basic vibration logging application for which I'm using TEDS enabled accelerometers.  I'm configuring a task using the Create Virtual Channel (TEDS AI Accelerometer) to add the correct channels, but none of the data from the TEDS table appears to be getting pulled into my channels. 
    Does this VI pull scaling information from the TEDS such that the values I read out are scaled to the appropriate unit?  Is there a way to force it to drag all the data from the TEDS through so that when I save a waveform to a tdms file they end up as channel properties?
    I've included a screenshot of the VI that creates the task for reference.  Thanks!
    CLAD
    Solved!
    Go to Solution.
    Attachments:
    Create TEDS channel.jpg ‏100 KB

    They are TEDS 1 accelerometers.  I can actually see the entire TEDS table both in MAX and in my code (I read out the bitstream for my own amusement). 
    To collect the data I'm using a DAQmx Read N Chan N Samp - 1D Waveform.  The output waveform array is wired directly to a TDMS write VI.  The properties on the channel end up as shown in the attached image; note that no scaling information is carried thorugh.
    CLAD
    Attachments:
    AccChannel Properties.png ‏37 KB

  • DAQmx Create Virtual Channel AI Temp TC Deg F Bug

    Found a bug in DAQmx Create Virtual Channel AI Temp TC Deg F when using a cDaq-9174 with a NI 9213 Analog Inpout module.  When I change from Deg C to Deg F I do not get the correct temperature.  In Deg C I read ambient temp of 21.84 Deg C Vs. when I select Deg F I read 18.33 Deg F.   When I use the DaqMX Assistant the asssitant returns the correct values.  Is this a know bug on the 9213 driver?  What is the fix?
    Solved!
    Go to Solution.
    Attachments:
    Read one AI Temp Channel in C or F.vi ‏13 KB

    Thank You - Found it here too

Maybe you are looking for