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
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Attachments:
nireport.txt 2 KB -
"I am doing a data acquisition project using a 16 channel N.I. series 6020E card where I want to capture respective current and voltage sinusoidal signals. I am planning on capturing four pairs of matching current and voltage signals. I planned on taking one reading across the channels every fifteen minutes. This reading will need to be 60 data points per period or 3600 readings per second per channel in order for me to recreate the sine signal to determine the phase angle difference between the voltage and current. I was able to get one channel to capture a signal but could not get more than one working at a time. I am also trying to sycronize the data collection so all samples are with respect to each other. Thanks for any help."
-posted by cappy on 2/11/2002
John N on 2/12/2002 answered:
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Could you post this question to the Hardware > Counter/Timer or Hardware > Multifunction I/O forums? I think you will get more responses there. Here is a link.
The hardware is usually a better differentiation since software can support such a huge range of functionality.
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If you have more questions, please post this to the other forum and copy all of our discussion to let everyone know what we have talked about already.
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I am using the USB connection. If anyone can help with or has a similar VI for this, it owuld be appreciated so I can work on the larger aspect of the total project.The easiest VI to use for this acquisition is AI Acquire Waveforms in the data acquisition palette in LabVIEW. This VI allows you to perform a finite acquisition from multiple channels on your DAQ board. As John mentioned the acquisition from individual channels will not be truly simultaneous. There will be a slight time shift from one channel to the next on the order of the maximum acquisition speed of the card, 100kHz or 10 microseconds in your case. By accounting for this 10 microsecond delay between consecutive channels you can properly calculate the phase shift between voltage and current.
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Christian Loew, CLA
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Please tip your answer providers with kudos.
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What amount of current is flowing ? Does it depend on the selected thermocouple type ? Can the current level be controlled by sotware ?
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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. -
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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
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with regards
madhava
Attachments:
Scanning_of_SCXI-1127_48_write.vi 144 KB
IM0000041[1].jpg 722 KB
IM0000041[1]1.jpg 722 KBHi 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.
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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,
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