N Channel independent configuration with DAQmx

For an application, where I need to give the user, the options of configuring 8 analog channels independently, what would be the best way to go ? ( He needs to set the min, max values, samples and acquistion type - SE, Diff etc )
Use 8 sets of "DAQmx CreateChannel( AI_Voltage_Basic)+ DAQmx Start Task + DAQmx Read VIs" or is there a VI which does this configuration as a single sub-VI ? I have searched enough to find one such.
Any ideas that can provide a compact solution would be welcome.
Thanks
Raghunathan
Raghunathan
LV2012 to Automate Hydraulic Test rigs.

Sean C. wrote:
Hello Raghunathan,
...you will have to create a Task with all channels you want to modify, then pass that Task to a Channel Property Node. You can then set the options for each channel independently. ...
See the attached VI for an example of this.
I hope this helps,
Sean C.
Applications Engineer
National Instruments
Dear Sean,
Thanks.
I guess I got your point. Let me repeat the steps - just to make sure:
1. In the example sent by you, create the required properties for all 8 channels using "add element".
2. Give a descriptive name for each channel.
3. Next click on each node and select "Create Control". This will provide the required user control on the panel.
4. Group all properties for each channel ( min, max,type,etc) properly and lay them out neatly.
5. Finally pass the duplicate reference out of this synthesised proprty node to a DAQmx Read VI.
Is that right ?
Now I think I sort of realise the power of DAQmx VIs.
Regards
Raghunathan
Raghunathan
LV2012 to Automate Hydraulic Test rigs.

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Message Edited by Tom W [DE] on 11-16-2007 07:54 AM
Tom W
National Instruments
Attachments:
autoCleanup.JPG ‏17 KB
clearTask.JPG ‏4 KB

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Attachments:
Divider_Config_mw.vi ‏40 KB

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Problem with DAQMX on a 6025E
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Attachments:
Write_Dig_Port.vi ‏48 KB

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CLAD
Attachments:
Build Daq Task Snippet.png ‏58 KB

Nope. That's a delete from array, length 1, index 3.
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CLAD
Attachments:
Build Daq Task Snippet v2.png ‏54 KB

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From my understanding you are using an SCXI 1001 chassis with an SCXI 1102 and 1303 terminal block to perform thermocouple measurements. You are upgrading to LabVIEW 8.2 and DAQmx. I am assuming you were using LabVIEW 6.1 since there isn’t a LabVIEW 6.5. You mentioned that are able to get a correct reading of 0.5 mV with LabVIEW 6.1 but you see a rail of 5V with LabVIEW 8.2 and DAQmx.
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Hello,
I am currently working on a Senior Design Project where I have to measure torque, RPM, pressure and temperature. I am using strain gages, a Hall Effect Sensor, pressure sensor and thermocouples to obtain these readings. A myDAQ collects the RPM and pressure readings while a cDAQ collects the torque and temperature readings with the NI 9237 and NI 9211 modules. I created LabVIEW VIs for each sensor and they work. The problem I am having is when I try create a VI with DAQmx that reads all these sensor values simultaneously. The VI that I have attached randomly displays one of the measurements while all the other measurements remain blank. How should I edit my VI so I can display all my readings at once?
Solved!
Go to Solution.
Attachments:
SD.vi ‏87 KB

You can form all of your cDAQ readings into a single DAQmx task. Do the same for the myDAQ channels. On the read side, you just read multiple channels. You can then use the Array Index to separate your channel data and do whatever calculations you need.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines
Attachments:
Multichannel task.png ‏40 KB

Can I measure pulswidths with daqmx base and NI-USB6501

Can I measure pulswidths with daqmx base 1.4 and NI-USB6501? I can measure edges width this function: DAQmxBaseCreateCICountEdgesChan. But, when using DAQmxBaseCreateCIPulseWidthChan I always get an error message back (DAQmxBase Error: <err>Value passed to the Task/Channels In control is invalid).
I also cannot find any examples about this topic in the software on CD nor on the internet.
I also don't know what values to use for the float64 minVal and float64 maxVal arguments when using the pulse width function of above (see the NI-DAQ™mx Base 1.x C Function Reference Help).
Maybe my device (NI USB6501) cannot measure pulse width's and when it does measure pulse width's, what value will it give back? Seconds or ticks and what is the accuracy?
Ok, enough questions for now. Thank you in avance for answering.
D. Stollman

The USB-6501 counter is capable of falling edge edge counting
measurements only, so the type of measurement you wish to do is not
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http://www.ni.com/pdf/products/us/20054920301101dlr.pdf
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When doing buffered events with DAQmx and PCI-6602 I get error 200141 - Data was overwritten before it could be read by the system.
This error is generated ONLY with random inputs >200/sec.
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DAQmxCreateCIVCountEdges(taskhandle,"Dev1/ctr3"....
DAQmxCG+FGSampClkTiming(taskhandle,"/Dev1/FPI35",...
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i'm getting the same Error-200141, while reading semiperiods. (Meas_Buffered semiperiod continous)
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Attachments:
Counter_1_Meas Buffered Semi-Period-Continuous_main_lv09.vi ‏34 KB
SemiPeriod_Reconnect Counter on Error.vi ‏35 KB

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Greetings,
I'm using a 6602 counter board with DAQmx 7.4, ANSI C API. A strange issue concerning the errors due to faulty attribute values keeps occuring, that being no error is reported when the (faulty) attribute value is set but only when it is read back afterwards. Shouldn't the faulty value be reported by the Set function?
To be specific, I'm creating a period measurement counter input channel with implicit timing, sample mode = finite, then setting the number of samples per channel to 0 (bear with me, I know the 0 value makes no sense here, the point is how the errors are being reported so that they can be handled in a reliable and consistent way). While DAQmxSetSampQuantSampPerChan(taskHandle, 0) does not produce an error, calling DAQmxGetSampQuantSampPerChan(taskHandle, &SampPerChan) for verification on the very next line returns Error -200077 : "Requested value is not a supported value for this property". So, my question is why the error is reported by the Getter instead of the Setter? Is this normal behavior (if so why?) or is something amiss here?
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One, when every attribute is set, NI-DAQmx could verify the value of that attribute in the context of the task (i.e., in the context of all other attributes). This is problematic for at least a couple of reasons. One, validating the task after every attribute is set is time consuming and not efficient. Two, validating the task after every attribute is set requires that customers set attributes in a specific order such that dependent attributes are set after their dependencies. This would dramatically decrease the usability of NI-DAQmx. In fact, if attributes are mutually dependent, this approach is impossible.
The second approach is that NI-DAQmx doesn't verify the task until it is forced to do so. Starting a task forces it to be validated. Querying an attribute also forces the task to be verified since the value of an attribute may be dependent upon the value of another attribute.
As you've noticed, we've taken the second approach with NI-DAQmx. This approach leads to a more efficient execution as well as allow customers to set attributes in an arbitrary order. If you want to force the task to be verified in order to check for errors, you can do so explicitly at the desired time. However, the need to check attributes for errors is most often needed when the application is under development and the NI-DAQmx error reporting features makes it easy to determine which attribute has been set to an invalid value even when that error is not reported immediately.
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Hope this helps clarify the behavior.
geoff
Geoffrey Schmit
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ipt_LOG ipt_limit nipxirmk nidimk nimsdrk nidmxfk nimxdfk nimstsk nimdbgk
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EFLAGS: 00010246   (2.6.13-15-smp)
EIP is at nidsark-unversioned0004550+0x70/0x11e4 [nidsark]
eax: 00000000   ebx: f6be1d68   ecx: 00000000   edx: 00000000
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ds: 007b   es: 007b   ss: 0068
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f95bbf19 f6be1bd0 f6be1d6c f6be1d6c f6be1b98
Assuming that the NULL pointer deference was caused by the preceding failed vmalloc, I attempted to increase the vmalloc size to 512MB (which is certainly overkill). This did nothing to clear the error. One final detail is that this computer dual boots Windows, while the others have only ever run Linux. It shouldn't matter, but I feel it is worth mentioning in the event that DAQmx for Windows somehow mangles the configuration of the card to a point where it no longer functions with DAQmx for Linux. It should be noted that the card works just fine under Windows.
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-Peter Lisherness
Message Edited by PeterLisherness on 07-10-2006 12:36 PM
Attachments:
dmesg.txt ‏5 KB

Peter,
I have a couple of other questions which might help us narrow this down.
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I checked the file as you suggested and i didn't find any tcp_lmtpss-daemon channel so i inserted the following lines:
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N Channel independent configuration with DAQmx

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