Crosstalk among Analog channels

The setup is this :
1. Card is PCMCIA 6024E.
2. Software is LV 7.1 and all reads are with DAQMx functions.
3. 6 analog channels configured in differential mode ( AIN_0 to AIN_5)
4. Connected to the card via BNC2110 connector.
If I connect only one channel to a signal, it is reflected in all the other 5 channels at different levels.
I do know that I can solve this problem by two means :
A. Ground the unused channels to AIGND.
B. Use alternate channels with one grounded channel in between two active channels.
In my case since I need all 6 channels at times, so option B does'nt exist.
Question is, can something be done in the software without resorting to option A.
I have attached the snap shot of my problem. The straightline plot is the channel that has a signal on it and the other "followers" are free channels. At 15:49:43 I made the active channel zero and you can see all of them dropping to zero. Then I started another channel and all of them pick up !
Kindly help solve this.
Raghunathan
LV2012 to Automate Hydraulic Test rigs.
Attachments:
FuelPump_06-04-05 _PM 03-50-08.jpg ‏86 KB

SE_Hoard wrote:
I would be interested in any solutions to your problem also. ... When I input a signal on CH0 it also appears on the other 7 channels. ....
I was searching the tutorials and application notes on the NI site. Located this PDF which discusses the aspect of amplifier settling times in a multiplexed front end of a multi channel DAQ setup. Just read through the recommendations and see if they can help to reduce crosstalk in your case :
http://zone.ni.com/devzone%5Cconceptd.nsf/webmain/B9B5D37A04C772B58625686500695C20/$File/AN045.pdf
Raghunathan
Raghunathan
LV2012 to Automate Hydraulic Test rigs.

Similar Messages

How can I detect an error on a single FP analog channel?

Hello! I am new to the world of LabVIEW, maybe someone can help me. I need to detect if ONE of the analog channels in FP-AI-100 is in error state, such as reading out of range. I have no access to working FP modules and have no way of testing my code. Could someone tell me if what I am trying to do is possible? I modified an example Analog Input.vi and wondering if it will work. I changed the input to Read block to read only one channel, not the whole module and examining the error status bit. Will this status bit display error only for selected channel or for the whole module? I need to ignore all other channels.
Thanks! Ellen.
Attachments:
Analog_Input_Error_Test.zip ‏12 KB

Hi Ellen,
I do not have LV 7.1 loaded so I can not look at your VI. Please post an image if you want me to look.
In theory, checking the boolean should work in finding error cluster that have the boolean set.
THe complication is this.
I have seen that some of the error codes returned by FP reads will either have or not have their booleans set depending on which version of the FP code you are using.
I saw in LV 6.1 that an "open RTD" (if memory serves me correctly) would return a true boolean if LV 6.1 was the latest version of LV loaded. After another engineer used LV 6.1 after he had loaded LV 7.0 the error boolean was no longer set!
THe definition of boolean set or not set from one version to the next!
So...
I must advise that you test each
type of error you want to support in your code with whatever version of code you plan to use to ensure the boolean will be set.
Trying to help,
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Ben Rayner
I am currently active on.. MainStream Preppers
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Best structure to measure voltage across 8 resistors in parallel via 8 separate analog channels

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What would the best structure be to run this test? I am thinking a Sequence structure, but it seems like people tend to avoid using that. Or would a case/while loop be better?
From my understanding, the data will not pass out of a sequence structure until it is finished. this doesnt seem to be that big of a problem for me, as I only want the data at the end....
thanks for the help!

Use a for loop. Put your code inside the loop, but delete the analog channel number. Make an array constant and poplulate the array with each analog channel number. If you wire the array to the loop (left side), you will see the terminal is a hollow box. This means indexing. The loop will operate on the first array element, then repeat with the second array element, and so on until all array elements have been processed. Wire the hollow box to the point in your code where the analog channel number was deleted. Now the loop will execute the same code using a different channel each time. If you wire the output to the right edge of the for loop, you will again see the hollow box. All of your measurements will be contained in an array at that hollow box. Process the outputs as you like, maybe display the entire array, or index the array to get the individual elements, whatever. The advantage of the for loop is that you have to write your code only once. Everything is seen on one screen making it easier to read. Sequence structures are not good programming practice because a lot of the code is hidden, and you have to go to different sequence frames to see the hidden code. Also, why duplicate the code in each frame when the loop will do it all. Good luck.
- tbob
Inventor of the WORM Global

Re: DAQ write+read analog channels

Thank you Dan,
The device used is NI_USB 6211 and the tests will be done by another person.
So from your email I understood that is not recommended to use Hardware Timed Single Point.
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Do you think this USB device will work at 5 KHz rate?
Anyway it seems it must be used sometime even at 10 KHz.
So I still waiting for a guaranted solution!

unintentional dup post. see here for discussion
Jeff

DAQ write+read analog channels

Hi,
I need some urgent help to solve a simple problem:
My job is to write an analog channel to a DAQ device and then to read two analog channels from the same device.
These should be done at the 5 KHz rate.
For smaller rates I can do it using normal loops (or timed loops). But I don't know how to do it using DAQ features.
Please give me an example.
I have found something but I am not sure if it can be used in this way (see the attachment)
Thank you!
Solved!
Go to Solution.
Attachments:
DAQ Test write analog+read analog.vi ‏49 KB

Mcdan wrote:
Quick correction to my last post... I did not notice that your original VI called DAQmx Start. In this case I think it is preferred to call start before your loop rather than calling commit, since start will put the tasks in running state outside of the while loop. In Jeff's proposed change, the tasks would need to transition from committed to running and then back to committed each iteration of the loop. As originally written, the tasks will be in the running state before the while loop and remain there until they are cleared.
Dan
Dan- You missed the Autostart(T)- and, ALL tasks go from committed to run and back to committed,( unless abnormally terminated by a explicit abort while running starting from a state other than committed,) the commit state is the least overhead for any task that is not continuous or regenerating. The original post started the task from Verify state- and required DAQmx to reserve and commit the DAQ resources for each read or write and then (since it Started from verify) implictilly uncommit and un reserve the resouce after "running" in each loop iteration. Sean N "Popped-the-hood" and gave difinitive advice on the DAQmx task state handeler in this post (warning ----wrap head with duct tape before reading)
Sorry to derail the thread but, accuracy counts too. I can't let a user stay stuck behind an "8-ball" with misconceptions (nice avatar by the way)
Jeff

Noise problem on analog channels

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I get the best result using an capacitor between the positive and negative terminals on the daq board.
PLEASE HELP!
/Anders

Hi Anders,
Quite unlikely that card is inducing some internal noise.
By selecting the range btw 0 to 1 V, you are only changing the ADC gain settings.
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Check this for both the ranges you talk about with suitable inputs.
Now, if you do not get noise, then connect sensor in a suitable single ended mode and see if this gives you a better reading.
If you are still getting noise, then i would suspect for improper chassis grounding
do tell if this solves your problem
Regards
Dev

Data aquisition from spectrophotometer in two analog channels, X-Y plot

Dear colleagues!
I am new to LabView and I am only starting to learn the system (I have never been a programmer, I'm a chemist to be precise).
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Thanks a lot, johnsold!
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C. Finally, is it possible to automatically stop the While loop when the number generated by shift register becomes equal to 190?
Here are attached a new code and a sample of data.
Attachments:
Tracor970A-v1.0.vi ‏53 KB
UV-test-01.txt ‏15 KB

Acquiring data from all the analog channels of NI-3202 NODE using a single sensor

Hi all,
I would like to know that can i be able to get the data from all the four analog channels of NI-WSN node 3202(analog input node) connecting only single sensor on the analog input and connecting all the remaining analog inputs using wires and also shorting the ground pins corresponding to each analog input pin.
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Thanks

Stefan,
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SCC Tutorial Series: SCC-SG0x
SCC Example Series: SCC-SG0x
Using the SCC-SG11 Shunt Calibration Module
Thanks,
Gio L.
Digital Support - Product Manager
National Instruments

I want to use two analog channels and one digital simultaneously

Hello and thanks in advance for reading this!
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I have already created a VI which activates a digital line and while I was trying to add with the NI-DAQmx Assistant the first digital output, I discovered that it c
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Log an analog channel and counter period channel to hard disk simultaneously

We are in a rush, and need to log one analog channel and one counter period measurement to disk simultaneoulsy using card controlled timing and set # of samples. Should be easy, but can't figure it out. Labview 6.1 we have & DAQ 6013E we just bought.

Greetings,
With regards to logging analog input data to file, I would suggest that you examine the examples available in the following location:
Examples >> Hardware Input and Output >> DAQ >> Analog Input >> Stream to Disk
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Need quick help, please!!! How do I scan the counter and analog channel in parallel, synchronized?

Hi,
I'm using LabView6.1 and a PCI6014 DAQ card.
I have to scan simultaneously an analog channel and the counter on the card. My project requires me to measure in parallel a force (a voltage on an analog channel) in correspondence to a distance (measured with a counter) and I have to display a force-distance graph.
So, can someone please tell me how can I program the counter and an analog channel to take 1000 measurements in parallel, and then, by reading the buffers to have two sets of corresponding measurements?
I've tried some things and I've got only an error message, that says that there is no free DMA channel available (the error comes from configuring
the analog channel). I attached one of these programs that gives this error, maybe somebody can tell me what I do wrong.
If somebody could send me an example (in LabView6, I have no 7 :-( ), I would be grateful.
Thank you,
pixooxiq
Attachments:
Scan_Test_4.vi ‏177 KB

Hi pixooxiq,
unfortunately, your Card has only one DMA-Channel.
If you want to use two Channels simutaneously, you have to tell one of them to use an Interrupt instead.
This option can be set with the "Set DAQ Device Information.VI"
Just see the Bitmap, I've attached.
Perhaps, you now get Performance-problems, cause the IRQ does not directly write the Data but involves the CPU. In this case the only possibillity is to use an other card with more than 1 DMA-Channel...
Regards
Peter Weber
NI Germany
Attachments:
Interrupt2.bmp ‏159 KB

Analog channel inserts with Logic

I continue to struggle with Logic Pro to get an efficient work flow when I use analog channel inserts during mixing. If I insert an analog compressor on a single channel we all know that there will be a delay in that channel with respect to the other channels. My solution is to nudge that channel to the left in anticipation of the delay. Supposedly, Nuendo and ProTools HD automatically compensate for that delay when an analog insert is used. I have hard time keeping track of which tracks are nudged to the left and which aren't as I am trying out various inserts.
I must be missing something. There has go to be an easier way. I vaguely recall someone mentioning something on a forum about a third party plugin that has the ability to correct for track latency.
I would appreciate comments from anybody using Logic with analog inserts. I am getting frustrated to the point that I am strongly considering picking up PTHD or Nuendo for this very purpose.

midnightsun wrote:
I continue to struggle with Logic Pro to get an efficient work flow when I use analog channel inserts during mixing. If I insert an analog compressor on a single channel we all know that there will be a delay in that channel with respect to the other channels. My solution is to nudge that channel to the left in anticipation of the delay. Supposedly, Nuendo and ProTools HD automatically compensate for that delay when an analog insert is used. I have hard time keeping track of which tracks are nudged to the left and which aren't as I am trying out various inserts.
This is NOT true. I have used both whilst using external compressors / reverbs / et al, and you still have to manually move the processed track afterwards. What I do, is process the track into a new recording, and then line it up. then use the compressor for something else, or remove it from the signal chain.
I must be missing something. There has go to be an easier way. I vaguely recall someone mentioning something on a forum about a third party plugin that has the ability to correct for track latency.
There is, you can use Logic's built in sample delay plug-in on all the OTHER tracks, the ones that are not going to the external device. Do a test where you find out the IO latency for the compressor or device, and set the sample delay accordingly. If your workflow demands it, that's the way to go.
I would appreciate comments from anybody using Logic with analog inserts. I am getting frustrated to the point that I am strongly considering picking up PTHD or Nuendo for this very purpose.
I do use them all the time, I have a bunch of outboard, which I use for tracking and mixing. I also have used PT HD and Nuendo in these very types of situations.
Again, you would be wasting your money. NO DAW can give you automatic delay compensation for UNKNOWN external devices. This cannot be, and this is why:
1. Once a signal has travelled to the physical output of the computer, there is NO WAY the computer can know where it goes, how long it takes to go there and come back. This is analogous to you throwing a rock around a corner, and knowing that it will go all around the building, WITHOUT LOOKING. And also, when a rock comes all the way around the building, it hits you, and you KNOW that's the same rock. This Physically Impossible. If you are skeptical, try it for yourself.
2. Likewise, a computer cannot possibly know that an incoming signal is the one you sent out previously. This is, because a computer cannot THINK. A computer COMPUTES. It does math for us, so we don't have to. We still have to tell the computer what we are inputting, and we also have to know what to do with what it outputs. One day, many years from now, we might have some AI in our computers. Yechhh. I like thinking for myself.
Cheers
Message was spellchecked by: comatose priests on a mission to get caffeine

DYNEX TV doesn't get all analog channels

I'm connected to cable, have indicated thru setup that I am so connected. When I run Autoscan, I do not get all the analog channels, only get thru channel 52. There is no Cable box -

I was just about to suggest what the last person posted, so I'll expand on the solution.
- Isolate the TV, if possible. Take the lead you have going into the splitter(s) and plug it directly into the TV so that it is the only TV on the line.
If you still cannot get channels, contact Geek Squad immediately and notify them of your problem so that you stay within your warrenty or return period.
I am a Bestbuy employee who volunteers on these boards on my own time. I am not paid for posting here, and you should understand that my opinions are exactly that - opinions. I do not represent Bestbuy in any way.
: Open Mailbox

Can digital and analog channels be simultaneously accessed

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Is it possible to simultaneously access digital and analog channels on
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threads using LabWindows/CVI (5.5.1)?
John.

Hi JAH,
I have no experiance with this product, so can not give you a definative answer.
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Also what version of the driver are you using, I have checked the
download page and version 2.1 only works for CVI 6 or higher and LV 7
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Regards
JamesC
NIUK AE

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My method is rather simple and bruteforce. If you have any suggestions for another way to go about this, I'd appreciate this. We want pretty much all of the timing to take place on the hardward, which is why these delays are in the FPGA program.
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Attachments:
biphasic.JPG ‏259 KB

Disregard the timing question, I've figured that out. If anyone has a suggestion for a more efficient way to generate this type of biphasic wave on the 8 channels, I'd still be open to getting that feedback!

Crosstalk among Analog channels

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