1. on page 2-4 of the manual (http://www.ni.com/pdf/manuals/375865a.pdf):
here is a sketch or a picture helpful to understand the text.
It is easier to understand page 2-4 with a small picture how to connect the AI SENSE for exapmle.
2. a terminal diagramm in the manual for each card (PXI, PCI) is also very helpful.
Alternatively a paper with the terminal diagramm to send with the devices.
Every time I have to work with a NI daq device the first thing i need to know is what pins can or cant do something.
Currently this involves looking through something like 7 diffrent documents to find little bits of information and bringing them back to your applicaiton.
A block diagram could easily be a refrence point for the rest of the documentation (you want to know about pin IO for your device look at this document)
Plus a good block diagram can tell you what you need to know quickly, and clearly. A picture is worth 1000 words?
Some might find the current documentation adiquite, but personally i would really like to have a block diagram that represents the internals and capiblities of the pins and device in general. Most Microcontrollers have this and it is an extremly useful tool. So why not have one for the Daq devices as well?
Hi Everyone. I have an old Kistler type 7001 pressure sensor and type 5007 charge amplifier and I'm going to use NI USB 6009 DAQ board to measure in-cylinder pressures of a single cylinder diesel engine.I'm very much new to Lab view and using all these sensors.Can some one kindly tell me how to start and I would be very grateful if someone could post a program (block diagram) to collect,convert the voltage to pressure and write the final output to a text file.Thanks alot in advance.
I use Daqmx a lot for writing .NET based measurement software.
Whereas the API itself is quite decent, the docs are horrible. Accessing them is convoluted at best, requiring the VS help viewer. Almost nothing is available online and decent examples are quite scarce, which will definitely be an issue for absolute beginners...
This definitely deserves some attention!
Including me, there are couple of other LabVIEW users, those wish to have this feature available, wherein we could be able to create Virtual channels (or even Global tasks) for an internal channel of a DAQ or SCXI.
This feature implementation should also include, allow to configure and use internal channels while using DAQ Assistant (though I personally don't prefer using DAQ Assistant).
Check this post here. This feature wish is around the same line.
Occasionally, I need to create global virtual channels that are used to acquire AC voltage signals. Currently, I just acquire the instantaneous values and take the RMS average in LabVIEW. However, this does not let you calibrate the global virtual channel in MAX (because the acquisition is the instantaneous DC voltage).
It would be nice to have the custom scales allow user customizable LabVIEW programming plug-ins, such as RMS average point by point, so that I can calibrate an AC voltage channel in MAX.
We use often the NI CompactDAQ 9234 for sound measurements.
Our standard microphones with iepe amplifier have a noise level of about 16 dB(A) and sensitivity of 40...50 mV/Pa.
The noise of the 9234 is about 50μV rms, corresponding to a sound level about 32 dB(A). So we can use this microphones only for measurement above 35 dB(A).
A better version of a card 9234 with 2 ranges 5V and 0.5 V would be very useful. The noise in the lower range should of course not exceed the range of 5...10 μV (12..18 dB(A)).
And many monitoring systems have only one Microphone, so we use only one channel of the 9234.
For this cases would be a lower priced one channel card OK.
A two channel card would be perfect: two channel measurement of one microphone signal in both ranges. The sound level program can measure from 20 dB(A) ... 136 dB peak without range switching.
I want to buy a small standalone controller based NI Data Acquisition system which would have the following features,
By standalone i mean that the DAQ system should be such that, it does'nt require a permanent PC connection (i.e. just program once). And it sends the acquired signals to a remote location via ethernet interface.
Please suggest me a DAQ system with the above mentioned features.
By default, DAQmx terminal constants/controls only show a subset of what is really available. To see everything, you have to right-click the terminal and select "I/O Name Filtering", then check "Include Advanced Terminals":
I guess this is intended to prevent new users from being overwhelmed. However, what is really does is create a hurdle that prevents them from configuring their device in a more "advanced" manner since they have no idea that the name filtering box exists.
I am putting "advanced" in quotes because I find the distinction very much arbitrary.
As a more experienced DAQmx user, I change the I/O name filtering literally every time I put down a terminal without thinking about it (who can keep track of which subset of DAQmx applications are considered "advanced"). The worst part about this is trying to explain how to do something to newer users and having to tell them to change the I/O name filtering every single time (or if you don't, you'll almost certainly get a response back like this).
Why not make the so-called "advanced" terminals show in the drop-down list by default?
With NI 9234 board you can use 4 IEPE sensors but you don' have IEPE open/short detection capability.
NI 9232 board has IEPE open/short detection capability but has only 3 channels.
I think that a board with 4 channels (as 9234) and an IEPE open/short detection capability would be great!
Currently we are using LabWindows/CVI with a 96 bit DIO card (PXI-6509).
What we have found and NI support confirmed is that with the following the software needs to be aware of the bit offset during a write to one or more lines on a port.
Virtual Channel Physical Channel
dataEnable dev1/port0/line 2
Our assumption was that writing to 'dataEnable' a value of 1 using DAQmxWriteDigitalU8() would write to the virtual channel 'dataEnable'. What we found is that is not the case. We need to write a value of 0x04. But that the bits that are set to zero in this value written to 'dataEnable' have no affect on other lines on the port that are already set. This gives us the impression that the driver has knowledge of what bit position we are trying to write too.
So based on this why is it not possible that when I call from LabWindows/CVI to do a write to a virtual channel I cannot just do something like this:
Virtual Channel Physical Channel
Line 2 = dataEnable
Line 3 = dataClk
write( dataEnable_Clk, 1) // to set enable line high
write( dataEnable_Clk, 3) // to keep enable line high and raise clk line
write( dataEnable_Clk, 1) // keep enable line high and lower clk line
write( dataEnable_Clk, 0) // lower enable line
** assumption is that seperate lines on another port are used to present the data to the external hardware and are not shown here. The data would have bee setup before the sequence above and then change data and repeat sequence as needed.
Here I don't have to keep in mind that Enable is on line 2 and Clk is on line 3 or have to setup values of 0x04 for hte Enable and 0x08 for the Clk. If I have to do this I would rather have direct access to each port to just write the values directly. i know there is the register level I can use but doing this at a higher level is better.
In our code when a internal function is called to write data we would like to just write a value out to the virtual channel and not have to figure out the bit alignment to shift over the value to use one of the current functions.
Let me know your thoughts.
I need to acquire signals from an incremental encoder and I have a board NI USB6259 to do this.
It seems that this hardware has special inputs for position acquisition from incremental encoders.
Looking at USB6259 datasheet I could make the data acquisition using inputs Counter/Timer.
If that is right I should send the square waves TTL generated from the encoder to these inputs but my encoder has sinusoidal outputs with a certain phase between two signals.
If I need to send TTL signal to my USB6259 I should convert sinusoidal signals with additional hardware.
Is everything right? Did anyone acquire encoder signals before? Suggestions?
Thanks in advance
Texas Instruments makes a superb line of 16-bit Sigma-Delta ADCs with sampling rates up to 10MHz: ADS 1610, ADS 1602, etc.
They sell for about $25 each in modest quantities.
Using these converters would provide much better fidelity than any available products as there is no need for external analog antialiasing filters.
I'll place my order now. I personally need 1,2,4,8 AIs and 1,2 AOs with same sampling frequencies from same clock. I don't need all those digital I/Os and quadrature decoders.
Just give me analog I/O with sigma-delta converters. When can I place an order?
We use our acquisition software with a variety of hardware configurations. We validate our configurations using simulated hardware, but every time we need to check out a different configuration, we have to delete and create simulated devices. It would be nice to have a better method for switching between different simulated configurations.
I bought a NI USB-6251 BNC but the support explained me that it would have no Linux support out of the box. I will have to find out how to use it on Linux systems myself now (perhaps with help of the forum). It would be a nice feature, if it would ship with Linux support.
Measurement and Automation Explorer MAX's Test Panel's Analog Input provides a quick method to examine a signal and vary acquisition parameters. It would be useful to be able to zoom the time axis and have a cursor display so that for example noise level or rise time could be looked at in more detail. The time axis limits can currently be manually overwritten as a way to zoom but that is cumbersome. Assuming the graph being used in this test panel is built from a standard NI graph, it should have zoom and cursor capability already part of it and thus easily added.
NI should make sure that the measurement uncertainty specifications for its DAQ hardware are aligned with uncertainty analyses that are performed according the ISO "Guide to the expression of Uncertainty in Measurement" (GUM). See http://www.bipm.org/en/publications/guides/gum.htm
Absolute encoders have been around for some time, but NI's motion hardware still supports only incremental encoders. I would like to see support for absolute encoders in NI Motion or NI Soft Motion.