Servo tune with analog input (no encoder)

I have a PXI-7340 motion controller and MID-7654/7652 Drive connected to a servo motor. As position information I use an analog signal, no encoder (it has to work in a radioactive zone and an encoder wouldn't resist). Can someone tell me how to find the PID coefficients in MAX and also where I can see the position information in MAX ? I use Servo Tune manually but no results .. the red line is always flat and the motor doesn't move;
thanks for any help,
otilia
otilia

Hello,
Have you taken a look at the following link?
http://digital.ni.com/public.nsf/allkb/19668AB2D4997F3D86256E940082F1EF
Message Edited by ThiCop on 04-23-2010 06:55 AM
Kind Regards,
Thierry C - Applications Engineering Specialist Northern European Region - National Instruments
CLD, CTA
If someone helped you, let them know. Mark as solved and/or give a kudo.

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Labview performance suffering with analog input

Hello,
I am using a PCI-6036E and a cDAQ-9172 with LabView 8.0. I have created a VI that systematically writes four different digital outputs, three to the PCI-6036E and one to the cDAQ-9172.
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Before installing the thermocouple, the VI slowed down a bit if left to run continuously (for days at a time). Now, however, the VI slows down a great deal if left to run for more than a few minutes. It is so bad that the "Elapsed Time" display will not properly display the elapsed time.
Because this application will be run for days, even weeks at a time without being stopped, this gradual decrease in performance is a huge problem. The application needs to run very accurately and precisely. I have attached my VI below. Is there any way to fix this issue? Any help is greatly appreciated, as I am new to LabView.
Thanks,
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I didn't look at the code (yet), but do you have a slow analog samplerate?
Look here
And here (a KB aticle)
Ton
Free Code Capture Tool! Version 2.1.3 with comments, web-upload, back-save and snippets!
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LF a home theater with analog inputs to support my creative x-fi 5.1 card. Budget is 225.

My card does not support true surround sound in anything other than movies through SPDIF so I need to get a home theater that has analog inputs. Could someone recommend me a good speakers system for 225 or less. I current have a 1000 watt JVC TH-G30 that uses SPDIF. Thanks for any help
My card is USB is why this is an issue.

'Re: Creative X-Fi 5. Surround Problem. Hi,
As far as I know, you can only get stereo audio from the optical output unless you are playing encoded Dolby or DTS audio. See this link for more info. http://forums.creative.com/creativel...&thread.id=270
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Dv video time stamp with analog input

Hi,
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Daniel,
Does your DV camera have any sort of timing or triggering signals? Without these, it will be virtually impossible to correlate measurements. It is cetainly possible to accurately time an analog input with your DAQ card, but correlating these to the digital video would be extremely difficult. Is this video streaming in real time? Or are you reading it off of an already-recorded tape? If this video is streaming in real time, with an acquisition started in software, I would suggest attempting to start the software DV reading at the same time as your DAQ task. If you do have an external signal that can trigger the video acquisition, then I would suggest using that same signal to start your analog acquisition.
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Product Marketing Engineer
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Measuring PWM duty cycle with Analog Input

Hello folks,
I have a NI 9205 module and was wondering if there was a way to measure the duty cycle of a PWM signal that I am generating with a separate microcontroller? I have found a lot of examples with Digital inputs but not analog.. Is this possible?
Thank you,
Bob

Hi Robert,
I'm not sure what that error is, try searching for it.
If you want to measure a PWM signal you would usually use a counter input. A counter is a dedicated piece of hardware that is used to measure digital signals. Since the NI 9205 is an analogue device and it doesn't have any counters onboard, you will not be able to select counter input.
I would recommend you get the right tools for the job and buy a digital acquisition device with an onboard counter. It will make reading PWM much easier for you. The NI 6008 has a counter onboard and is only £99. It will also offload processing from software to hardware since you don't have to calculate duty cycle.
If you still want to use analogue post back and we can look into why its not working for you. Tips to start you off: Voltage is the correct setting and Look in the manual and make sure you have connected it like you have configured it (differential, RSE, NRSE page 14)
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My question has to do with analog input and triggering? Does anyone have any suggestions on how i can improve the attached vi so it can trigger on a 50kHz ten cycles pulse after the pulse has been sent out on the output?

Could you just look at this vi and tell me if i am doing anything wrong? I get errors that are different each time I change something. here are the inputs I am using
Output Side:
amplitude = 1
freuency = 50kHz
Sampling Frequency = 1MHz
3 of Samples = 200
Input Side:
Input Buffer 4000
trigger type = analog
pretrigger = 5
edge or slope = rising
scan rate = 500kHz
# of scans = 2000
Conditional Retrieval
mode = on
slope = rising
skip count = 0
level = .1
offset = 0
hysteresis = 0
So what we want to do is capture the ten
cycles of the 50k output pulse on the input and need to store that so we can plot it later, do you have any suggestions. we are using the PCI-MIO- 16E board.
Thanks,
Jarrod
Attachments:
InputOutput2.vi ‏88 KB

1) Toss the sequence frames (no flames please).
2) Set you read and have it ready to trigger before oing the output.
3) After the output, go back and read the data that is waiting for you.
4) If you have errors tell us what they are and under what conditions they occured.
End of Ben's suggestions for now.
Ben
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Synchronizing two counter frequency inputs with multiple analog inputs

Hello all,
I'm fairly new to LabVIEW and I'm trying to collect data from multiple sources with synchronized timing on the acquisition but I'm having trouble figuring it out. My problem is that I've got two counter frequency inputs, one optical tachometer reading one pulse per revolution, and a max machinery flow meter with a k factor of 12000. I can't seem to figure out how to sync the timing with my multiple analog inputs. I've been attempting to get the tachometer to sync with the analog inputs first by following the example linked here. (https://decibel.ni.com/content/docs/DOC-10785) So far each time I run it I either get a timeout error on the DAQmx read or a "Multiple sample clock pulses were detected" error (see attached image). It seems if I slow the sampling rate way down to say 10 hz and ensure that the tachometer signal is over 800-1000 RPM (13-17 Hz) before starting the VI then the program will run without errors until the RPM drops below that threshold then the "Multiple sample clock pulses" error occurs. The code is attached below.
Does anyone know of a more effective way of syncing counter frequency inputs with analog inputs? I'd like to have a VI that can show 0 RPM (and eventually 0 flow as well, but I think I need to figure out the timing of one counter before I add another as it seems I can't have two counters in the same task). Any help on this would be greatly appreciated.
LabVIEW version 13.0
cDAQ-9178 Chassis with NI 9401 for the two counter inputs and NI 9205 for the analog inputs.
Thanks!
Richard
Solved!
Go to Solution.
Attachments:
SimpleDAQ.vi ‏44 KB
LV_Error.JPG ‏31 KB

Maybe third times the charm?
So I've finally got a good handle on why the VI is having problems at low RPM though I'm somewhat embarassed how long it took me to do that
Because I have the counter time synced to my Analog input task if it doesn't see at least two pulses between the two clock pulses set by the analog input task I get the -201314 "Multiple sample clock pulses" error. This seems fine at first as it just sets a minimum RPM that I can measure and it's well below the area I'm interested in so no problems there. I tried a simple error handler that would clear the error when it happend assuming the loop would keep iterating until the RPM went above that minimum at which point I would get a signal again. This is not the case, the read function just continues to spit out the -201314 error even after the RPM is back in the readable range. So then I tried adding two case structures so that when the error occured it would stop the task, clear the error, and then start the task again on the next loop iteration (Code Attached). This also doesn't work as the error shows up again on the stop task and then AGAIN on the start task on the next loop iteration. It seems this error is not actually being cleared and once it happens it stays with the task regardless of what the error cluster is carrying.
Anyone have any ideas? The only solution I can think of is to just clear all tasks and recreate them each loop iteration until the RPM is readable again but that strikes me as a horribly clunky solution.
Richard
Attachments:
SimpleDAQ_1_Start Stop.vi ‏48 KB

Measuring frequency with counter or analog input?

I have some frequencies which I need to measure. Some signals are digital and some are analog.
I have a PXI-6040E DAQ which has both counters and analog inputs.
I heard that you can measure higher frequencies with the counters than with analog inputs.
What is the range of frequencies an analog input can determine versus a digital counter?
Where is the cutoff that you must absolutely use a digital counter to determine the frequency?
Is the cutoff different for different DAQ cards? Or is generally the same.

Have you looked at the specs for the device? The max sample rate and the max counter input will be listed there. The max frequency for an analog input is based on nyquist sampling theory. Are you at all familiar with? It states your sampling frequency has to be at least twice the frequency you are measuring.
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I am getting a -50101 error when trying to get analog input from a compact rio

I am just doing the initial setup of my compactRIO system and have been able to successfully add the cRio in Max and then into a new project. I created a very simple VI with analog input that I am trying to read into an indicator, following one of teh tutorials. The module I am reading the input from is a cRio-9201. The input is voltage. I have already added the module to teh project under the FPGA, which is under the RIO in the project tree. Any ideas what I may be missing would be greatly appreciated!
Thanks

The 9201 C Series module needs to be created under the FPGA Target
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How to use counter output pulses to trigger analog input?

Hello all,
I hope the kind people using this forum can help me, a lowly beginner LV programmer! I have been attempting to create a VI that produces a user defined number of TTL pulses, separated by every n seconds. Each TTL would be outputted to a stimulator, which in turn generates its own TTL. Using the stimulator-generated TTL, I would like to trigger finite analog data acquisition (e.g. for every TTL, trigger the collection of a data sweep that contains 4000 samples (collected at 4000 Hz), with 1000 samples collected pre-trigger. I would like to also be able to see each data sweep as it is triggered on a chart. As I understand things (lots of online/book/forum reading), I should be using the counter output to generate my TTL pulses, and syncing each counter produced TTL with analog input, as well as using a reference trigger. Also, the AI part should be started first, so that I don' t miss any counter outputs. If it matters, I also need to use one of the AI channels to acquire the TTL, so I can see my stimulator-induced responses to the stimulator in time.
I am able to generate the TTL pulses from the counter output, but I am having a problem with the AI part. I am unsure how to sync the counter output with AI. Also, since I need to acquire pre-trigger samples, I would be needing to acquire samples continuously, but when I set 'continuous samples' on daqmx timing, the VI doesn't work (hence why's its set to 'finite samples').
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Attachments:
RC001 v_1.vi ‏49 KB

Hello,
Due to the fact that analog tasks themselves are not retriggerable, a
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for analog input. This can be done by creating a finite pulse train set
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===If this fixes your problem, mark as solution!===
Attachments:
RC001 v_1mod.vi ‏25 KB

How to use both digital and analog input modules in the same worksheet - MCC USB1208LS

Dear all,
Hi, I am Imran. I am using MCC USB1208LS. I have created the worksheet using digital input module as below and able to execute (run).
But when i add another analog input module in the same worksheet and executes, An error Message pops-up as in the below image
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is any black box solve? please guide me. I am attaching in images
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Attachments:
present worksheet digital input only.JPG ‏67 KB
with analog input module.JPG ‏81 KB
error menu.JPG ‏77 KB

Hello Imran,
the USB-1208LS is not capable of running concurrent operations such as an analog input scan and ANY digital Ins, Outs, counter reads, or analog outs. In Dasylab, the 1208LS is scanning, and nothing else from that particular device can be requested of it while that is happening.
Yes, using the 1208FS will resolve some of these issues.
Please refer to the ULHELP.CHM file installed on your computer in c:\program files\measurement computing\daq for details on this issue, et al.
also I recommend you send your MCC/DASYLab requests for support to [email protected] as MCC staff (that includes me) does not normally monitor NI's Developer Zone.

MyRIO analog input express Vi (n samples) missing file

Dear Users,
I am trying to read analog data with an express VI in myRIO. This works with Analog input (1 sample), but fails with Analog input (n samples) due a missing file "myRIO v1.1 FPGA Throughput.lvbitx".
I googled it and searched it on ni.com, but nobody seems to have the same isssue (I suppose because of the myRIO is quite new right now)
Thank you!
Solved!
Go to Solution.

I would try doing a repair of your installation. It looks like something didn't get installed properly.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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Interference of analog inputs

Hi,
I have problem with analog input measurement. I am using NI PCIe-6351 for measuring voltage signal from 3 sensors - accelerometer (differential connection to AI4) and 2 pressure sensors (differential connection to AI0 and AI1). If I measure signal from accelerometer and pressure sensors separately using SignalExpress everything seems working. However if I measure these signals together it looks like they influence each other, concretely analog signal of accelerometer increases value of pressures during dynamical measurement. Measuring only pressures looks all right.
Behaviour of signals is shown in the figure below. Upper two figures show separate measurement of signals AI0 and AI4, bottom figure shows signals measured together/simultaneously (signals are noisy but they should be constant).
Thank you so much for your suggestions.
Jaroslav Bušek
Attachments:
ni.png ‏15 KB

Dear Jaroslav!
If I understand your image correctly, the issue is the oppositve of what you described, so the accelerometer (AI4) is being affected (offset by a fairly constant DC value) by the pressure measurement (AI0). What is your measuring frequency?
There are a few suggestions off the top of my head:
1. Check shielding on your sensors to ensure on crosstalk is happening on the measurement itself.
2. Create a dummy task on AI3, measuring a constant 0 to zero out your ADC in between channels.
3. Depending on your application, you could decrease the sample rate on one, or all sensors.
Hope some of this you'll find useful.
Best regards:
Andrew Valko
NI Hungary
Andrew Valko
National Instruments Hungary

TV tuner Card for Mac with Component input

Hey everyone, I was hoping someone could help me find a good TV Tuner card for my MacBook. I found a few potentials, however I've yet to find one with Component input that would allow me to play my XBox 360 at a resolution of 1050p. This is the resolution of my stand-alone monitor, and with S-Video the resolution would drop into the 400's. Does anyone have any suggestions?
Thanks,
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Does this work with a Mac? Looks like from the screenshots this is only compatible with Vista
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Producer consumer with analog and digital inputs and outputs

Hi everyone,
I am working on a control system program for some practical test work. Currently I am working on the data acuisition component of the Labview program. My architecture is produced-consumer loops with a que. My system will have analog inputs, analog outputs, digital inputs and digital outputs. It's not a time critical sytem, but I would like all of the data acquisition to be synchronised. I have attached my program as it is at the moment. I am having trouble getting all of the data into the que since I have two data types. Also, I'm not sure if i've synchronised the four read/write sequences correctly. I would greatly appreciate if somebody could take a look at my program and give me some advice. Thanks in advance.
Solved!
Go to Solution.
Attachments:
control_v2_DAQ loop.vi ‏46 KB

Robert, the specific error that I get is:
Error -200462 occurred at DAQmx Start Task.vi:6
Possible reason(s):
Generation cannot be started because the output buffer is empty.
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This error occurs at the 'DAQmx write.vi' function. I just want to sent one sample per second, for each channel. I would like the producer and consumer loops to each run once every second.
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Attachments:
control_v2_ML_simple.vi ‏83 KB

Servo tune with analog input (no encoder)

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