NI cDAQ-9172- measuring voltage

This is probably simple to do, but was wondering how to measure the voltage of the NI cDAQ-9172 connected to my labtop?

You need to be more precise on what modules you have in the chassis.
What are your LabVIEW version?
Have you tried some of the examples that is following NI-DAQmx ?

Similar Messages

Strain measurement using 9237 and cDAQ 9172

I am trying to measure strain using a 9237 and cDAQ 9172.
The strain gage is connected to 9945 (Red wire to EX+, White to IN+ and Black to QTR terminal also tried connected the white and black to IN+ terminal).
The 9945 is connected to 9237 quarter bridge strain measurement module on a cDAQ 9172. I have two 9237 on the cDAQ 9172.
The device passes the test in MAX.
The problem is I cannot read the strain value.
Can anyone help me please?
Attachments:
Strain measure.vi ‏19 KB

Hi jujare,
In the VI you attached, you don't have the bridge configuration set up. The default is full bridge I, so if you have a quarter or half bridge wired up, that is one reason you could be getting bad data. I'd suggest you take a look at "Cont Acq Strain Samples(With Calibration)-NI 9237.VI" in the Example Finder. It shows the configuration for bridge type and has some handy wiring diagrams. You could also add controls to your vi to set the bridge configuration if you'd prefer.
If your strain gauge only has three wires, it's probably a half or quarter bridge. A full bridge needs at least four wires.
I hope this helps!
Regards,

Measuring voltage and temperature

Hallo,
I've got the problem of measuring voltage and temperature simultaneously, with diferent numbers of samples. I want to use two of the "DAQmx write", but then the error "The ressource is reserved" appears.
Software: Labview 8.2.
Hardware: NI cDAQ - 9172
NI 9211 (Temperaturecard)
NI 9201 (Voltagecard)
How can i fix it?
Attachments:
Fehler.JPG ‏89 KB
Fehlerbeispiel.vi ‏27 KB

Hello LochiMD,
there are sereral things you have to care about.
The best would be, you have a look on the following link:
Synchronize continuous Acquisition of Multiple Analog Input Devices
https://decibel.ni.com/content/docs/DOC-12182 (Have a look on the picture, especially left side)
You should use the VI DAQmx Timing (Sample Clock), samples per chanel and sample mode is necessary.
If you do this, your program should work.
Best Regards,
Nina

NI cDAQ-9172 is not recognizing a NI 9237

I am trying to use a NI 9237 with a NI cDAQ-9172 to measure pressure using a pressure transducer. When I plugged the 9237 into the cDAQ it was not recognized. As I remember with this piece of eqiupment, once a module is plugged in it should be recognized and configured. Any ideas?

Hi Matthew,
I'm wondering, do you have the driver installed? As well, is your chassis recognized in Measurement and Automation Explorer? Does the New Found Hardware issue ever pop up when you connect your device? Thanks!
aNItaB
Applications Engineer
National Instruments
Digital Multimeters

Encoder Speed with NI 9215 module and cDAQ-9172

I've a NI cDAQ-9172 with the NI9215 analog input module, and I want to estimate the speed with an optical encoder (OMRON E6A2-CW3C). My approach was, making a comparison with a point in the midle of the high of the signal, ie 4V, making this way a perfect square signal with 1of high. After that I use the Tone Measurements and the Timing and Transition Measurements modules to calculate the frequency of the wave form, and this way I'm able to calculate the RPM speed.
The problem with this solution, is that even with the engine at a constant speed of 746RPM, measured with a stroboscope, Labview give me a high variable values between 730RPM to 760RPM, and I can't solve this problem because I really need an accurate measurement.
Should I buy for example the NI 9401 module to make this measurement? If so, does any one knows how to build a VI to get the encoder speed?
In attach I send the VI that I'm using to calculate the speed.
Thank you for help.
Attachments:
Encoder Speed.vi ‏112 KB

Hi,
The best way to measure a speed through a quadrature encoder is to use the counters that are inside the cDAQ chassis.
With the 9172 chassis, you need a digital I/O module (9401) in order to access the counters.
With the new generation of chassis (9178), you don't need the 9401 because you can connect your encoder signals to the BNC.
Best regards,
Thomas B. | CLAD
National Instruments France
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How syncronize PCI4472 with cDAQ-9172?

I need syncronize the acquisition of 32 channels from PCI-4472(8 channels) and rack cDAQ-9172(16ch-9233(4modules) + 8ch-9234(2modules)). I tried several arranges but dont get to do work. I have a 9263 auxiliar module if necessary.
Can anyone help me? A second problem when i do the aquisiton without syncronize is get waveforms with differents DTs between devices.
VI in attached. Thx.
Leonardo de S. Cavadas
Maintenance Engineer and Inspection - Bureau Veritas do Brasil
Engineer Metallurgist with emphasis in Advanced Materials
Technologist in Computer Science
Attachments:
ProdCons2Devices.vi ‏61 KB
CH23DT117.PNG ‏46 KB
CH24DT125.PNG ‏46 KB

Hi Leonardo,
to use trigger from cDAQ-9172, you need an additional hardware-timed digital module to access the PFI lines. The hardware-timed digital module must be installed in slot 5 or 6 to access the PFI lines.
Thus, you can use PFI line from PCI-4472 to synchronize your measurements.
I hope I help you.
Regards,
Ricardo Ramos
Engenheiro de Vendas - Sul
National Instruments Brasil

Finding NI cDAQ-9172 chassis

Hello,
I cannot find the NI cDAQ-9172 chassis in measurement and automation..Right now just specified as unidentified. Could anyone help me with this?

Hi lakersrl,
For reassociating a device with DAQmx from Traditional DAQ, read this article here. I would try this first before reading forward.
The cDAQ chassis uses USB to communicate to your PC, so as soon as you plug in the USB cable and have your PC powered on, it will automatically identify the chassis and detect the modules, and display them in MAX. USB is hot swappable, so whether you plug it in with the PC powered down or on, you should see the hardware come up automatically. When you plug in the device, the Add New Hardware Wizard should show up and start associating drivers with their respective devices.
The picture you see is from previous versions of DAQmx. Before v9.0, we had a separate folder listing that housed DAQmx Devices under Devices and Interfaces. Post-9.0, we took that folder away, and now all devices show up under Devices and Interfaces.
When you plug in your hardware, can you see anything show up in your Device Manager on your computer? Any unknown devices or National Instruments devices? If you do see some listing, it would be a system software issue and I would look at trying to repair DAQmx or reinstalling to get the hardware identified correctly in the OS. If you cannot see any listings of the hardware in Device Manager, there is some issue with the hardware, and I would try different USB ports, try getting it to work on a different PC, check the USB cable and connections, make sure the cDAQ chassis is powered on and that connection is good.
If you still cannot get this chassis to identify, has it ever been identified and working on any other system or time? It could possibly be damaged, and may need repair for it to work properly. Testing on a different PC with DAQmx installed would be a helpful troubleshooting step to see if the issue is system specific or hardware specific.
Kyle A.
National Instruments
High Speed Digital I/O Product Support Engineer - R&D

Counter issues with cDAQ-9172 and 9401

I'm trying to do a pulse count with a 9401 module in a cDAQ-9172 system. My problem is that the count always ends up in the 30 kHz range, when it should be in the range of 1 kHz - 5 kHz. Furthermore, the pulse count doesn't change even when the input pulse frequency is changing. I've used a multimeter to verify that the input signal is pulsing at the expected frequency. It seems like the system is counting the wrong thing (maybe defaulting to some sort of internal timing device?), but I can't figure out what it is or how to fix it.
Any advice would be much appreciated.

Thanks for the response. MAX basically confirms what I've been finding.
Some more specifics:
I have two counters set up, only one of which should be getting a signal at a time. When I connect a function generator sending a square wave to one of the counters, that counter reads the correct frequency and the other counter reads zero - exactly what should happen. When I connect the signal I'm trying to measure to an oscilloscope, it shows a square wave with the frequency I'm expecting. However, when I connect the signal to one of the counters, that counter reads the wrong frequency, and the other counter is counting pulses when it shouldn't be receiving anything at all. The only thing I can think of at this point is that somehow my signal is creating some kind of noise that causes incorrect measurements on both counters, but this doesn't make a whole lot of sense to me, as the oscilloscope shows a pretty solid square wave. In fact, the signal doesn't really look appreciably worse than the output of the function generator. Even if there were some noise, it would have to be pretty severe to affect the edge count, I believe.
Essentially, I've been able to convince myself that the incoming signal signal is an acceptable square wave with the expected frequency, and that the DAQ system is capable of counting pulses on a similar square wave when it comes from a function generator. Somehow, when I try to combine the two it doesn't work, so I'm at a loss at this point.

Encoder speed and orientation on NI 9401 in cDAQ-9172

Hello, I've acquired a ni 9401 module for my cDAQ-9172 and it's now installed in slot five to connect a dual channel encoder. Channel A is connected to pin 14 and channel B to pin 17 and the encoder is powered by 5v dc.
I want to mesure the speed and if possible the orientation of rotation.
To do this I started with the VI in attach, that can count the total of pulses in the encoder.
My question is, how can I change the DAQmx Create Channel to Frequency, and the DAQmx Read to Counter Pulse Freq 1 Chan 1 Samp, to calculate the actual encoder speed and orientation?
Solved!
Go to Solution.
Attachments:
encoder.vi ‏63 KB

Hi Eric.
Once again, thank you very much for the help.
I think I finally did it. The Vi is reading the speed witch I think is right, but there's some oscilation.
I've connected only the signal A from encoder to pin 14 on the NI-9401, and the pin 1 to ground. The signal B is not connected right now because I only have one NI-9401 on a cDAQ-9172, so only one counter.
The VI you just send me, is calculating the speed (frequency), witch I divid by 200 because those are the pulses per revolution of the encoder, but I can see a little of oscillation on the speed measured (see picture in attachment).
For now, my question is if is possible to improve the measurement, and how?
Thank you.
André Quintino.
P.S. - Note that in the picture in attachment, the speed is the one measured by the VI you just send me. The encoder was running at 1524RPM witch are 25,4Hz. Since the speed in the graph is multiplied by 200 (the pulses per revolution of the encoder), this result in a measurement of 5080 witch is the average number by the graph.
Attachments:
Screen shot 2011-01-12 at 00.41.13.png ‏16 KB

CDAQ-9172 Calibration Procedure

Is there an official calibration/verification procedure available for the cDAQ-9172 chassis? I haven't been able to find one on the NI website.
Specifically, I want to verify the accuracy of the timing functions provided by the USB-STC2 timing engine in the chassis.
Thanks in advance,
Mark Moss
Electrical Validation Engineer
GHSP

Hello Mark,
Unfortunately, there is no calibration procedure for the cDAQ-9172 chassis. In fact, National Instruments offers no calibration services for the cDAQ-9172 chassis. I'm just guessing here, but I think that the reason is because the only thing that is really in the chassis are analog input and output timing engines, and signal routing lines. I can tell you that the analog input and output timing functions are specified at 50 parts per million of the sampling rate. The base clocks for the counters/timers are also spec'd at 50 ppm. If you want to check to see how accurate the clocks are, you would need to have an oscilloscope and a clock signal of known accuracy, and you would have to route the timing signal to a PFI line or other signal line that was accessible externally. You would then have to trigger the clock signal of known accuracy and the cDAQ-9172 timing signal at the same time, and measure the difference. For more information on calibration of National Instruments products, I recommend that you view the Calibration FAQs on the NI website.
Best wishes,
Wallace F.
National Instruments
Applications Engineer

How do I acquire multiple signals in the NI cDAQ 9172 using 2 analog input modules?

Hi everyone,
Is anyone familiar with using the NI cDAQ 9172? This is my first time using it and I am not sure what exactly I am doing wrong... Alone with a NI 9233 analog input module, it works great. I can grab my 4 signals from each channel and go. However, when I add another analog input module to the mix, it gets an error. It looks like it is reading only one and not the other. It bombs at one of the DAQ start task and read task.
Basically, the block diagram is just a double of the one 9233 working alone. Is there something needed for input to make the 9172 working? Any ideas?
Any help is much appreciated. Thanks!!

Hi Jud,
Both threads are correct. The cDAQ-9172 has a single analog input timing engine, so both of your analog input modules will need to be in a single task. The other VI you referenced shows one analog input task (with channels added from two modules) as well as an analog output task. Analog output has a separate timing engine from analog input, so both of those can run in parallel independent tasks.
The beginning of this thread is a good example; a single DAQmx Create Task followed by a DAQmx Create Virtual Channel for channels from each module. Also, Getting Started with NI-DAQmx will give you the fundamentals for data acquisition, though I don't know how many of their examples use CompactDAQ.
Regards,
Kyle

Programmed vs measured voltage on Keithley 2400 and other things

Hello everyone,
I have two issues with our Keithley 2400, which we control through Labview, and I would be very grateful for some help/advice. The issues are listed below:
1) We use the 2400 for 4-point probe measurements, so we plot graphs of current vs voltage to get the resistance from the slope of the curve. However, when we look up the data generated during a measurement, the voltage sweep values that we program often, but not always, do not match the measured voltage values. For example, what was meant to be 1 V, might actually end up being 1.2 V or maybe 0.8 V, this can be both positive and negative with respect to the programmed values and is not constant. This also leads to the fact that our curves, although straight (so Ohmic conductor), do not go through the (0, 0) point on the graph.
2) Second problem is that we would like to determine what is the time between successive measurements in a voltage sweep. We have tried some example vi files that by default come with the Labview, e.g. Keithley 24XX Read Multiple - SW Trigger or Keithley 24XX Read Multiple. If someone knew how to find the time separation, then we would be grateful. We only have control over the number of invididual readings taken and the timeout, which we guess is the maximum time allowed for the measurement.
Many thanks!

Good Afternoon PiotrW,
1. Could you please provide the code you are using to program the voltage sweeps?
2. You could use the timestamp output of the Keithley 24XX.lvlib:Read (Multiple Points).vi to allow you to find the time difference between successive samples. It should be a simple case of subtracting succesive measurements from each other to find the time difference between data points.
Regards,
Al
Regards,
Al C
National Instruments,
Application Engineer

Can the USB-9211 Thermocouple Input device measure voltages ?

Can the USB-9211 be used to measure voltages ? It is designed for thermocouple measurements and its operating manual states there is a current source between its TC+ and TC- input terminals.
What amount of current is flowing ? Does it depend on the selected thermocouple type ? Can the current level be controlled by sotware ?
One application for me is to measure resistances of 1 ohm or less by measuring the voltage drop across the resistance induced by flowing a current through it. Might the 92111's current source be somehow used for this ?
What is its peak to peak input noise ? Its specs say 1 uV rms.
This is a delta-sigma converter. Is each successive measurement accurate or does some digital filtering have to be account for and thus it takes several readings for a signal change to become accurate ?

The 9211 measures voltages between 0 and 80 mV only. The current source is only use to force a full scale input if an open thermocouple is connected and cannot be controlled by software. The input impedance of each channel between TC- and TC+ is 20M Ohm. However, the current that flows in the amplifier is very small, 50 nA.
The main problem here is the fact that the current source is not controlled by the user. This means that connecting a resistor of 1 Ohm between TC- and TC+ would not just produce a voltage that maybe due to external exitation, but the internal source should also be taken into account. Since the user has control over it, it would be a guess work to try to make sense of any voltage value read in.
its peak to peak input noise is 1 uV rms as indicated in the specs.
So as long as the measurements allow for enough settling time (12S/s), each one is accurate.

Sample rate for digital sampling (cDAQ-9172 & NI 9401)

Hi!
I have a cDAQ-9172 with a NI 9401 C-series module (digital). I would like to sample the digital inputs with a sample rate of e.g. 400 kHz or 200 kHz. My problem is that I can only select a the 100kHzTimebase clock, and therefore only get a 100 kHz sample rate. The 20MHzTimebase clock is too fast, since it gives me a sample rate of 20 MHz). Is it possible to get a user defined sample rate of e.g. 200 kHz, by e.g. dividing down the 20MHzTimebase clock?
Solved!
Go to Solution.

The cDAQ-9172 chassis does not have an internal timing engine for digital input however you can use one of the onboard counters to generate your clock. Set your pulse train generation counter to be one of the internal counters, such as "cDAQ1/_ctr0" and your digital input sample clock source to be /cDAQ1/Ctr0InternalOutput".

Trying to measure voltage through 1 wire connection

Hai ,
I am trying to measure voltage through 1 wire connection using NI hardwares like 1)chasis SCXI-1000 2) DMM PCI- 4060, 3) MUX SCXI-1127 and 4) Terminal Block SCXI-1331. Please see a attached picture of my set up.
I am unable to establish my connection through 1_WIRE_LO_REF .I want to use it as my reference point (GND) through which I can measure the voltage .I think there may be problem in my design or in the labview code.Could u please verify and suggest the appropriate one.
Can I use 1_wire_Lo_ref is so which port to be used, actually i have six ports for this point (or) is there any altenative
I hope u respond soon and in the affirmative
with regards
madhava
Attachments:
Scanning_of_SCXI-1127_48_write.vi ‏144 KB
IM0000041[1].jpg ‏722 KB
IM0000041[1]1.jpg ‏722 KB

Hi Madhava,
Are you unable to get the example program to work? Are you using an Aux cable to connect the switch to the DMM or are you triggering from the connector block of the switch?
One good resource is to open the NI-Switches Help from Start >> Programs >> National Instruments >> NI-Switch >> Documentation >> NI-Switches Help. Go to the Search tab and search for Single Module Scanning - Handshaking. There are sections for SCXI or PXI depending on which form factor you are using. This will explain which triggers to use and how to connect the DMM and Switch together.
In the same help file, if you search for Scan Lists, this will show you the proper syntax for the scan lists. The scan list can all be listed in one text box and does not have to be an array of strings.
I think the best way to proceed is to take the example that I showed you save it as a new program so you can go back to the original if you need, make it work and then modify it to do what you need. Add the write to file for example. If you have any questions about specific issues, I can help you with those.
Thank You,
Nick F.
Applications Engineer

NI cDAQ-9172- measuring voltage

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