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NI 9265 Outputting current to VFD

December 5, 2017, 8:46 am
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We are currently having trouble outputting a current signal to a VFD. The signal must be between 4 mA and 20 mA. An external power supply is connected to NI 9265 and the VFD is connected to one of the analog outputs of NI 9265. 

 

We set the blower capacity at a certain percentage using a sliding scale. That capacity is then divided by 100 to convert it into decimal form. Next, the decimal form is multiplied by 0.016. Finally, to convert this to the 4 mA to 20 mA form, we add 0.004. This number is then fed to the express VI. An on/off switch is used to control the while loop.

 

We believe wiring of the hardware is all correct. Could anyone help with troubleshooting the code? The VI is attached.

 

Thank you in advance!

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Configuring ethernet port without NI MAX

December 5, 2017, 11:36 pm
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I want to connect NI cDAQ 9188 chassis onto a windows 10 device. For that, I have installed NI DAQmx 17.1.1 runtime. While using ethernet, I found that it is already reserved for LAN by corresponding driver. I do not want to install NI MAX from NI DAQmx because of space constraints. So I would like to know if there is a way to detect chassis from device manager settings or command prompt or any other thing like that.

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Analog input recording Issue with USB X series NI USB-6343

December 6, 2017, 9:34 am
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I am having a synchronisation issue when recording analog inputs.  I have replicated this in a few different mediums now but my example from NIMax is below.

I've set up a task recording on 2 analog input channels recording a 500Hz 0.5 duty cycle digital pulse which I set externally and which is fed into both channels.  As you can see from my first attached image 'recordingTimingCorrect.png' this gives the readout you would expect with the two recorded signals perfectly synchronised

However if I add a digital edge trigger then the signals are now offset as seen in 'recordingTimingIncorrect.png'.

I first discovered this from C# and from my tests there I know that there is a single extra sample on the first channel used.  It is also always on the first channel used (in NIMax this is the first channel in the order). This means if I now add a different channel to start of the channel order but keep the two which are there afterwards they are now correctly synchronised even with the trigger.

Is this a known issue?  If so is there a known workaround?  I would really like my inputs to both be externally triggered/timed and synchronised.

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multiple PCI-6024E or one PCI-6071E

December 7, 2017, 2:01 am
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We have in our possession four PCI-6024E and one PCI-6071E and we want to sample at least 60 channels all using the same gain with maximum samples/sec using Labview.

The 6024 does 200ksamples/sec while the 6071 is capable of 1.25msamples/sec.

Can somebody points me to the cons and pros of using 4 (synchronized) 6024's or one 6071?

 

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Low cost control for solenoid valves

December 7, 2017, 3:48 pm
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I need to switch 7-9 24V solenoid valves (between 0.2A and 0.8A draw each) at a short distance from the main PC, so I want to run just USB or just ethernet.

I am already going to use a USB Multifunction DAQ (USB-6008) for analog input to take sensor readings. It would be nice to use the TTL-signals from DIO of that card to switch industrial relays (DIN mountable), but the only products I could find were non-industrial relay boards with built in transistors, intended for Arduino/Raspberry Pi. So the solution I have is adding another USB DAQ with SSR outputs (USB-6525) and using that to drive the coils of industrial relays.

 

Is there a better way to do this? Are their industrial relays that take TTL-level input? Is there an NI card to handle all of this?

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Choix d'un systéme d'acquisition CDaq 9174 et NI-9205

December 8, 2017, 1:19 am
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Bonjour à tous,

 

J'ai besoin de vous pour me donner des informations supplémentaire sur mon projet. Il consiste à récupérer plusieurs tensions de potentiomètres et de capteurs. Le potentiomètre varie de 0 à 10V et cette variation ce fait en fonction d'une distance entre le potentiomètre et un point fixe, plus on est loin plus de ce points fixe plus la tension est élevé. Avec ces deux paramétrés je voudrais ensuite trouver une vitesse et la tracer graphiquement. Les capteurs eux me permettrons d’acquérir une pression lu direct. J'ai au total 8 potentiomètres  et 3 capteurs de pression. Tout les potentiomètres et capteur sont câblés sur deux port D-SUB. C'est pour cela que j'ai décidé de prendre un CompactDAQ 9174 et deux modules NI-9205 qui me semble le plus performant pour l'utilisation que je veux en faire.

 

Je vous demande alors de me conseiller sur les différents appareils mit a ma disposition pour optimisé mon système d'acquisition. Et pourquoi pas me donner quelque idée pour la suite de mon projet.

 

Si vous avez plus de questions pour une meilleur compréhension de mon projet allez-y.

 

Merci d'avance pour votre aide =)

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USB-6343 Error -201295 Upon Self Calibration Plus Unresponsive AO

December 8, 2017, 3:05 am
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Hey All,

Noticed two of the AO channels are giving anomalous outputs (one is at 1V, another at +3V) with no signals being put through them. I have used the MAX test panel to set the output to 0 however this doesn't change the output.

I therefore tried the self-calibration to see if it resets the output voltage and I receive:
The device could not be calibrated.
Status Code: -201295
Device could not complete the calibration operation.

Calibration could fail for the following reasons:

1. The actual reference signal applied for calibration was different from the value you specified. Ensure that the reference signal applied is the same as the values that were input.
2. The reference signal was not stable over the period of time that the hardware was being calibrated. Ensure that the reference signal specified is free of noise and does not drift over the duration of the calibration.
3. The device is not functioning properly.

So far, in attempts to fix this, I have reset config data and restarted controlling PC before attempting a new calibration. After I had done this, the self-calibration date still shows 29/11/17 (when I did the self-cal upon receiving it). I have tried a different USB port (it is running on USB-3) and throughout these attempts I still receive same error code.

I found a previous topic, and I tried using the self calibration VI within labview. when I have run it, it doesn't show an error, but nothing is updated in terms of calibration date and it doesn't change the AO voltages.

I am currently trying to run the DAQ Diagnostics Utility, it can detect device, however upon calibration test the program just hangs and does not progress past "Running Calibration..."

Any ideas anyone, as I am stumped as to how to proceed now?

Regards

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The suitable data acquisition card for an application.

December 10, 2017, 12:07 pm
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I am running a system with five measuring instruments. Two thermocouples, two differential pressure transducers and one flowmeter.

I receive analog signal from all of them. mV from thermocouple, voltage in range between 0 and 10 volt from differential pressure transducers and current in in range between 4 and 20 mA from the flowmeter.

I need to acquire data by 100 samples per second rate, for almost 1 minute. I need to be accurate in my data measurements, especially that recorded from the thermocouples.

 

Could you please recommend me the suitable data acquisition card for that application.

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External sample clock divider

December 11, 2017, 9:17 am
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I have some experience with CompactDAQ systems, but I have now reached a point where I am not sure if (and how) it is possible to do what I wish.

 

I have a cDAQ-9174 with a 9411 (slot 1) and a 9205 (slot 2).

 

I have created an analog (Voltage) task which is externally clocked from an input on the 9411 board.

The issue is that the frequency of the external clock is too high, and I would like to divide the clock 2 or 4 times to reduce it.

Is this possible? I should probably mention that I configure the tasks using NI MAX.

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Modern USB DAQ for CB-68LP 68-pin out?

December 11, 2017, 1:56 pm
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Hi! I have a few applications that utilize a CB-68LP. I'm debating if I should replace them with complete USB DAQ devices or if there was a particular USB DAQ device that might interface with that pin out. We are phasing out the last of our hardware that used PCMCIA DAQ devices (DAQCard 6024E) and I'm trying to figure out the best path in the upgrade. I'm not particularly attached to the CB-68LP, but there is a lot wired to it and that would have to be redone.

 

Thanks!

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Pausing analog output using compactDAQ 9189 and NI9260

December 12, 2017, 4:48 pm
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Hi everyone,

 

I'm using a compactDAQ 9189 chassis with one NI9260 24 bit analog voltage output channel. I'm using the C-library in Python to control the instrument and Windows 7 (I also have Labview installed, both produce identical results). My goal is the following

- Load a periodic waveform with let's say 1000 points per period (=100 ms). Repeat this single period 100 times and stop the task. 

- Have exact control over timing during playback of this waveform. Ideally I would pause between each sample point for a short amount of time and tell it with a trigger when to advance to the next point in the waveform. 

 

I have tried the following two approaches, based on  the cDAQ9189 manual and posts on this forum. After setting up the task and channel, I configured the pause trigger polarity at my PFI0 input of the cDAQ chassis. Then I configured the measurement to run continuously with DAQmxCfgSampClkTiming: sampleMode set to DAQmx_Val_ContSamps, and to allow regeneration using DAQmxSetWriteRegenMode. This then leaves me two options, either have the regeneration happen in the output buffer on the computer, or onboard, thereby bypassing the output buffer. Here I ran into trouble:

  1. For onboard regeneration, I tried to set the AO_UseOnlyOnBrdMem property to True, but the driver returns the error message before the task is even started (error number -200077): 
PyDAQmx.DAQmxFunctions.InvalidAttributeValueError: Requested value is not a supported value for this property. The property value may be invalid because it conflicts with another property.
Property: DAQmx_AO_UseOnlyOnBrdMem
Requested Value: 1
Possible Values: 0

Question: Does this mean that the NI9260 doesn't allow this property to be set? Since that would seem strange, what could be the other property that conflicts with AO_UseOnlyOnBrdMem?

2. If I can't use AO_UseOnlyOnBrdMem, I'm stuck with 127 samples in the FIFO buffer (see NI9260 datasheet) compared to 8192 samples otherwise. In this mode, I can successfully start the task and after receiving the first pause trigger the AO generation starts and ends when the pause trigger goes low (perfect). However, upon receiving the 2nd pause trigger to resume the AO generation the driver throws an exception. 

 

PyDAQmx.DAQmxFunctions.OutputFIFOUnderflow2Error: Onboard device memory underflow. Because of system and/or bus-bandwidth limitations, the driver could not write data to the device fast enough to keep up with the device output rate.

Reduce your sample rate. If your data transfer method is interrupts, try using DMA or USB Bulk. You can also reduce the number of programs your computer is executing concurrently.

 

I understand that 127 samples empty in about 10 ms for my example waveform. It seems the computer can't keep up with replenishing this buffer. I am using the USB Bulk data transfer mechanism, already with a low sample rate of 1.6 kHz and 20 samples in the buffer as a test. 

Question: How can I get either of these two to work so that I can step through the waveform playback using the pause trigger signals. Or maybe there's a secret option number three, and I'm open to that as well.

Another question I have is: once this is working properly, what is the time between receiving the pause trigger and continuing the AO generation?

 

I've attached a picture with the other settings I'm using for the NI9260, maybe one of them clearly conflicts with the onboard memory settings I am trying to set. I've also attached a screenshot of a Labview program that creates the problem in 1. Any help would be appreciated.

 

Best,

 

Gerwin

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Typical accuracy for NI 9207

December 13, 2017, 5:54 am
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Does NI quote anywhere "typical" accuracy values (e.g. 25 +/- deg C) for the NI 9207?

 

The datasheet only has "maximum" values (worst case of 0.19mA), but I can see that the device's accuracy in realistic operating conditions is more than an order of magnitude better than this. Unfortunately, I don't have the traceable equipment to calibrate this myself.

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Building scope with Ni-6229

December 13, 2017, 8:32 am
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Dear Lab-View explorers,

 

I want to build some kind of scope with NI-6229 card. I made some preliminary program but I have a problem with data reading. In the program I've built I want to read analog signal from some device. First I've connected the function generator to the card to check the program but I have a problem. When I deliver low frequencies it is not problem at all.

Here is the picture with Measurement&Automation Explorer: (10Hz as I see in the function generator)

1.jpg

And the program itself:

2.jpg

 

But as I increase the frequency the program shows me some mess unlike the measurement&automation explorer.

 

Can you tell me please where is the problem?

 

Thank you.

 

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Shielding for PCIe extender - NI-6323

December 13, 2017, 11:01 am
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I am looking to use a PCIe extender for the NI-6323 PCIe connection. I am looking to have this be about two foot long ribbon cable. I am wondering if anyone has done something similar and have had any issues? Have you found that the PCIe ribbon absolutely needs to be shielded or not? A cable I am looking to use does not have any shielding.

Thanks,

Jamie

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Determine if a device is primarily a thermocouple device?

December 13, 2017, 1:36 pm
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This should be a simple question and I also wasn't quite sure which forum to put it in but... can anyone tell me a good way to tell if a device is primarily a thermocouple device, like a USB-9211A? A USB-9215 will cheerfully report that it can do thermocouple measurements but I want to identify devices that are intended for it.

 

I can just simply try to start a task using the built in CJC and if it errors, consider it not a TC device, but I don't love this approach; I can also just check against a list of device types, but that's not very future proof. Any thoughts on this greatly appreciated!

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Sinewave "noise" within RMS Measurements of each cycle (6225 & 6255)

December 14, 2017, 8:55 am
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I have 2 signals of 3200Hz signal which I acquired with both the PXI-6225 and PXI-6255, and in both cases I get a noisy sinewave within the RMS of each cycle.

 

Function GeneratorFunction Generator

Quick description of the above chart:

I have AI67 and AI70 (setup as differential with AI75 and AI78 on the common), both reading a 3200Hz generated by a function generator at 449200 Samples/s for 1 second.

Each point on the chart represents the RMS of 1 sine cycle (156 points).

This also includes "ghosting filters" of 100K&47uF on the following AI channels: 68,76,71,66.

The PXI-6255 is directly connected to the Function generator through a SCB-68.

 

What can cause this ripple in the sinewave RMS?

 

When I use the Frequency calculator of the Measurement pallet I get 3195Hz with the PXI-6255 and 3190Hz with the PXI-6225.

Frequency.png

 

I monitored the Tick Count before and after the DAQmx Read and it is exaclty 1000ms. The waveform data has an accurate dt and number of samples. How can 5Hz (6255) & 10Hz (6225) disapear if all the timing seem accurate?

Both a DMM and oscilloscope confirm the 3200Hz signals of the Function Generator and the FPGA generated signals.

The FPGA originally generated 6 sine signals, which I stopped to only have 1 in order to avoid cross-talk.

 

The original signal source is an FPGA which I have more data than the Function Generator.

PXI-6255 (499200 Samples/s for 1s for each channel) (156 samples per cycle) where I monitor 2 signals at the same time:

image.png

 

PXI-6225 (243200 Samples/s for 1 second) (76 samples per cycle) where I only monitor each signal separately:
image.png

 

Setting the AI at 5V or 10V range makes no difference.

 

Lowering the sampling rate at 124800 just made the RMS more noisy:

image.pngimage.png

The cause doesn't seem to be ghosting. I grounded the second signal with the function generator (same effect with the FGPA generated signal):

image.pngimage.png

 

Sample of 1 cycle (FPGA generated signals with PXI-6255):

image.png

Shouldn't the "Timing Resolution" and "Timing Accuracy" be constant and not distort the measurements?

 

Attachments are a sample of signals from the function generator and FPGA. PXI-6255 is used for both at 499200 samples/second per channel.

The sampling rate is automatically calculated using the maximum rate (SampClk.MaxRate):

image.png

Files are too large to be attachments.

Thanks

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NI 6211 - running 2 AO channels simultaneously

December 14, 2017, 9:10 am
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Hello,

 

I'm trying to use NI USB-6211 DAQ's 2 AO channels to run simultaneous sawtooth waves. AO0 to run continuous sawtooth at 40000 Hz, with 1024 sample. AO1 to run one cycle of sawtooth at 40Hz, with 512 sample. I use sample clock as a trigger pulse to camera which has to sync with AO0's sample rate.

When I run my code, AO0 works fine (sawtooth, static move, all works) but AO1 doesn't work. Can anyone suggest what I'm doing wrong?

 

Thank you.

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How to receive 500 KSPS analog data with Advantech PCI 1716U?

December 14, 2017, 4:37 pm
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Hello everybody.

 

I have some trouble to get 500 KSPS data via PCI 1716U. my program is attached to this post. It works properly with the sample rate under 200.

 

Could anyone help me to solve this?
I will thank you find mistakes in the program.

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How to receive 500 KSPS analog data with Advantech PCI 1716U?

December 14, 2017, 4:37 pm
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Hello everybody.

 

I have some trouble to get 500 KSPS data via PCI 1716U. my program is attached to this post. It works properly with the sample rate under 200.

 

Could anyone help me to solve this?
I will thank you to find mistakes in my program.

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NI9237 and TEDS - Which calibration templates are supported?

December 15, 2017, 1:50 am
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Hi

 

I want to use TEDS with the NI9237 in a CompactDAQ system. Is calibration template 40 (calibration table) supported by this device?

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