RSE mode measuring voltage

To whom it may concern:
I would like to post this question here so that it is easy to understand.
I would like to ask how 6250 measure the voltage using AI+ and AIGND. One of your collegue told me there is no current flowing to Rin if AIGND = Vs(0). I am trying to measure 100ohm resistor using AI+ and AIGND. I used DMM to measure from the top the resistor to AI+, the current was 0A and measure the current from the bottom of the resistor to AIGND. The current is 0A.
In fact, how 6250 measure voltage . If you put DMM instead of 6250, there is current going through DMM and you can show voltage. How about 6250. Could you please tell me?
I have attached a picture to let you understand what I mean. and where I got the information.
Here is the link
http://zone.ni.com/devzone/conceptd.nsf/webmain/D59654FA44D2F9FA86256F4A006064F3
Attachments:
First%20Picture.jpg ‏33 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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Hello,
For troubleshooting bad readings, probably the first thing to do would be to check the board's configuration.
Is it configured in differential mode? Differential mode is the most recommended mode for thermocouple readings. When using differential mode, just make sure to connect the positive lead of the thermocouple to ACH0 (for example), and the negative to ACH8.
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Hallo,
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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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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.
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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.
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Regards,
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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.
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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
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madhava
Attachments:
Scanning_of_SCXI-1127_48_write.vi ‏144 KB
IM0000041[1].jpg ‏722 KB
IM0000041[1]1.jpg ‏722 KB

Hi Madhava,
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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.
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Thank You,
Nick F.
Applications Engineer

How can i synchronize analog output and analog input timings to generate and measure voltage at the same time.

how can i synchronize analog output and analog input timings to generate and measure voltage at the same time.

Read this Tutorial
http://zone.ni.com/devzone/cda/tut/p/id/3615#toc3
And also refer to this link where You have repeated this question.
PS: Please stick to one thread. That way, its easier to keep track of your query and answers

How to measure voltage?

Equipment used:
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What am I trying to do:
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What I have done:
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- In VI Logger, I have created virtual channel that is reading Voltage (max 50V, min -50V).
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but it doesn't. It is always 5V that is not true. I have tested the device in the test panel and Vout (ch0.) is always 5V exact.
How
to solve this problem? What and how should I check, have I connected everything properly?
Thank you.
Regards Slav.

I had a similar problem. I changed the input from differential to single ended and it works. You need to connect your V- to Agnd. Unless there is a reason you need to read differential...thermocouples that I set up work fine in differential but there is no common ground to a voltage source.
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Tim
daemon wrote:
> I am using a NI AT-GPIB/TNT PnP board !! I am trying to use it to measure
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Shall I use NRSE or RSE mode for reading the output voltage of my sensor?

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Hi David,
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For more documentation see:
http://digital.ni.com/public.nsf/websearch/D509679FFAE2764386256297005D0C9D
http://zone.ni.com/devzone/conceptd.nsf/webmain/177A8B29FEDC0F5886256FA90083C0F8
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How to measure voltage changes using a NI-9219 with strain gauges and use the data in labview

I am updating an old LabView/Data Acquisition system that uses strain gauges to measure two forces (normal and axial) as well as two moments (Pitch and Roll). I am having trouble reading the voltage changes over my strain gauges using my NI-9219 as well as filtering the data with both a lowpass and smoothing filter. The program attached has the project and should have all the sub-vi's used in the program. This program was written on LabView version 8.5 and is being updated to a 2013 version of LabView. Also, the hardware previously used was a combination of a NI SCB-68 and NI USB-6251. If anyone could help me it would be greatly appreciated!
Attachments:
New SSWT.zip ‏751 KB

Hi Coffeyfj,
Did you ever had this set up working? The first thing that I would do as I mentioned in the previous comment would be to use one of the LabVIEW examples. I recommended to you using the (strain - Continuous Input.vi). If you can read any voltage changes with the example vi, then we will know the problem we are having is in your code. If you cannot read any voltage changes using the example I mentioned, we can start trouble shooting the hardware connections. Are you connecting the excitation voltage? If yes, Are you making the right connections. Please refer to page 19 of the following document (half and full bridge modes)
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http://digital.ni.com/manuals.nsf/websearch/4197ED4BD126E0B486257546005851CA
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How to use NIDAQmx to measure voltage, resistance and thermocouples

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Attachments:
675977 - Multiple AI Tasks.JPG ‏21 KB

Measure voltage on telephone line without adding noise?

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Any help is greatly appreciated.

Hmmm, are you making a phone tap?
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Trying to measure voltage through SCXI-1127/1331 1-wire connection

We have NI hardwares like: 1) Chasis SCXI-1000, 2) DMM PCI- 4060, 3) MUX SCXI-1127 and 4) Terminal Block SCXI-1331
We have a system with two large glass plates standing vertically and placed parallel to each other each having 24 electrodes on them. Distance between them is 4-5 inches. The plates are places in such a way that the electrodes are on the outer side and accessible to the user. We are trying to flow different liquids of different density through the channel in between. Please find attached a picture of it.
So a total of 48 electrodes and hence, wires are connected, 24 on both sides. On each side there are 3 rows with 8 electrodes/row, making a total of 24 wires. Wire#1-24 are on side A (say) and wire# 25-48 are on side B (the other side). The medium between the two sides will be salted water (say for now).
We want to measure potential/voltage in such a manner so that we can calculate the voltage difference between all possible electrode combinations between side A and side B. Like V1-25, V1-26, V1-27,...,V1-48,V2-25,V2-26,........,V24-48, all 24 X 24 possible combinations. We are connecting two end of a power source to side A and side B so that there is some current flowing in the water.
I have connected wire# 1-48 to 1-48 in SCXI 1331 (left out the zero to avoid confusion). Now that I'm measuring values through the program attached ("Scanning_....vi"), I can see that the first 16 values are showing some values of standards E-2. But from 17-48 are showing values of standard 5E-3 and I guess they are not taking any values at all. Can you tell me why this might be happenning?
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Another thing, in one of my previous contact with NI someone mentioned connecting 1_WIRE_LO_REF. Is it needed in this case? If yes, then if I connect one end to 1_WIRE_LO_REF, where should I put the other end?
In case the program is wrong or more than 16 values can not be taken please let me know alternate path or show me how to make changes in the program. I would appreciate your help in this issue. Thank you.
Message Edited by ERT_LSU on 09-17-2007 12:16 PM
Attachments:
Scanning_of_SCXI-1127_48_write.vi ‏144 KB
IM0000021.jpg ‏767 KB
IM0000041.jpg ‏722 KB

I connected the COM of my power source to the 1_WIRE_LO_REF. There are 4-5 points to connect. I choose the middle slot. Is there any significance of assigning so many slots to 1_WIRE_LO_REF?
No change in result. Can you please test run the program I attached and see whether it's correct or not. You'll see 48 segments getting the output. First 16 of them are showing some seemingly proper values. rset are either too small or as big as 5 V.
I'm providing 5Vs from the power source. You might have seen the old analog ones. I'm using one of them. there are different Voltgae option. I'm using the 5V and so I've connected a wire from the 5V connection to one of the electrodes on B side (28th electrode) and the COM ports goes to the A side (4th electrode) and also to 1_WIRE_LO_REF.
Now I'm thinking if the program if not working. Because it seems that we are getting (seemingly) proper values for the first sixteen and something's messing up the values for the the rest of the electrodes.
Do I have to use two 24X1 MUXs i.e, use physically different boards and also two different programs to measure them? Or I can just use 1-24 as 24X1 and 25-48 as another 24X1 in the same board and measure them through the same program? Thanks in advance.
Message Edited by ERT_LSU on 09-17-2007 04:00 PM

RSE mode measuring voltage

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