Negative analog trigger voltage

Hello,
I am currently working on a program in Labview 6.1 with two E-series devices acquiring data simultaneously. I am currently using a analog channel to trigger the acquisition. My application uses a signal that has both positive and negative voltage sources. Right now, when I set a voltage, the devices wait until the voltage level is reached before acquiring data. Well, if I am relying on a voltage that is always going to be negative, that value will never be reached. I guess I need to take the absolute value of the voltage coming from the trigger channel and then trigger if the absolute value reaches a preset value. Can anyone help me with this?
Thanks a lot,
Taylor

Taylor,
Since you are using an analog trigger, you should be able to set the analog level in the AI Start vi. I have attached a vi with just the AI Start.vi and the needed settings for what you are trying to accomplish. Let me know if this helps. Thanks and have great day!
Regards,
Lon
Attachments:
Trigger Config.vi ‏19 KB

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How can I set up a delayed analog trigger on PCI 6115 DAQ

I have an S-Series PCI 6115 DAQ which I’m running with Labview. I’m using it to measure signals from an acoustic emission sensor and two force transducers. I’d like to set up a delayed analog trigger which will start acquisition on all three channels a period of time after a selected channel’s voltage exceeds a threshold.
Currently I’m using the AI Config VI in line with the AI Start VI and AI Read VI to capture data after a analog hardware trigger occurs. A software trigger probably wouldn't work because I have to sample my data at 10MS/sec. My setup works fine for triggering without any delay or skip counts. However, if I set the delay or skip count in the additional trigger parameter field of the AI start VI, there is no effect, and the device still starts capturing data immediately after the trigger is received. What is the cause of this, and how can I get around it?
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rpursley8 is right about needing to get the counters involved if you want a hardware timed delay in your application.
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Otis
Training and Certification
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How Do I enable multiple trigger voltages on the PCI-6221 using NI-DAQmx?

I am using the PCI-6221 to do some simple data acquisition. The idea is to allow three different analog voltages to trigger the data acquisition state. I currently have the code set up for one voltage trigger but I am not sure what needs to be done to add the two additional trigger voltages. Any ideas?
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Is it possible to do something as simple as this:
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Monitor multiple channels for analog trigger with DAQmx drivers

Hello! I would like to start a data acquisition of multiple analog channels (16) from an analog trigger. I would like trigger to monitor four of the (same) channels, and trigger when any one of them reaches a certain voltage. I found an example that would work with the Traditional DAQ drivers (using occurances), but can't figure out how to do something similar in DAQmx.
Time is also an issue, as I would like to collect the first 80 milliseconds of data after the trigger (at a rate of 500,000 Hz).
I'm using LabView 7.0 and collecting data off of two PXI-6133 cards.
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Hi Denise-
After some research, I have found that it is not possible to use the functionality of DAQ Occurrences in DAQmx. Ironically, the reason that this functionality is available in Traditional and not DAQmx is due to the exploitation of an inherent limitation of Traditional that was upgraded in DAQmx. The multi-thread capability of DAQmx is a major advantage for most applications, but in this case it prevents the use of occurrences as they existed in Traditional DAQ.
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Please let me know if the attached example is helpful for your application. You will see the input channels listed in the format "DevX/ai0:y" where X is the device number and y is the highest channel number of interest.
Regards,
Tom W
National Instruments
Attachments:
Cont Acq&Graph Voltage-Int Clk Analog SW Trigger.vi ‏83 KB

Error 200284-DAQmx Analog trigger

Hi,
I am trying to start data acquisition (e.g. input channels ai6 to ai10) and save it to a file based on an analog input voltage signal change (acquire whenever ai6 >2 Volts) that will work as a trigger.
I also found an example that is pretty similar to this (attached). The trigger source in my case is the first analog input channel. Following the attached example, I am always getting the error code 200284 after running the vi. Basically it gives the error after the specified timeout.
I am using PCI-6289, but the problem is I cannot use any PFI lines for the voltage trigger and have to use ai channels only for trigger.
Can't figure out what is wrong.
Any help is highly appreciated.
Thanks,
Roy
Attachments:
cont_acq_volt_analog_start.vi ‏79 KB
cont_acq_volt_analog_start.vi ‏79 KB

Yes, you must use a digital channel as your trigger source because it has a different clock. Remember, something has to activate your trigger! For instance, let's say you want to use PFI0 as your trigger...when PFI0 goes high, start collecting data.
How do you plan to control when PFI0 goes high?
It can be an external trigger. It can be another, digital, DAQmx task, where the DO line is hard-wired to PFI0. But something has to cause PFI0 to go high, in order to trigger your task.
Since you can only have a single AI task, since there's only one AI clock, you have no way of ever generating a trigger. You won't start acquiring until you receive a specific signal on an AI channel, but you won't receive that signal until you start acquiring. See why it's a no-go?
So you want to acquire for 3 seconds after getting a signal on ai6 that's >2V. So let's think this through, ok?
If we set our task to finite samples, and we set our number of samples to 3000, what will happen?
We'll acquire 3000 samples. Right? Right! If our acquisition rate is set to 1kHz, it will take 3 seconds to acquire those samples.
While we are acquiring those 3000 samples, we may (or may not!) see ai6 go over 2V. Let's say we see ai6 read >2V after 2 seconds -- that is, our second loop iteration. Since we've set our # of samples to acquire at 3000, we've already acquired 2000 samples (assuming a 1kHz sample rate). That leaves us 1000 samples until our task expects to terminate (after which, you'll get an error). That's not 3 seconds worth of data, is it?
What if ai6 never goes >2V within our 3000 sample window? Now you haven't collected anything, and your task will throw an error if you try to collect beyond 3000 samples.
So no, setting our samples to finite and specifying the collection of 3000 samples isn't going to work, is it? Clearly not. That's 3 seconds' worth of data, all right, but it may not be the right 3 seconds' worth of data. Since you don't know when ai6 will be >2V, you need to continuously acquire samples.
Do you suppose we could do something with keeping track of time? Specifically, the time at which >2V was detected? Compared to the current time? And take action based on that? The logic for your case structure will become slightly more complex.
Do you know about shift registers? I'm not trying to be insulting, you said you were new and I'm not 100% sure of how new you are. :-)
You seriously do need to take your Write to File out of your DAQ loop...please look into producer-consumers, or you'll be right back on this forum asking us about buffer overflow errors. :-) Also, beware of the Write to Measurement File Express VI...you don't have a file path wired in the code you showed, so it's going to pop up a dialog box every time it's called, asking for a file path.
If you really want to learn LabVIEW, you will get rid of all Express VIs in your code. At the very least, you need to understand exactly what they do and how they work. Writing code that you don't understand is only going to cause problems later

I use a PCI MIO 16E board with an analog trigger. So I wire chann

el 0 to the PFIO line, and I enter "PFI0"as the triggering channel on the front panel , I put a level,and I declare channel0 and 1. When I do a DAQ it seems that PFI0 detects the signal as I haven't a timeout, but it doesn't trigger off at the good level.

el 0 to the PFIO line, and I enter "PFI0"as the triggering channel on the front panel , I put a level,and I declare channel0 and 1. When I do a DAQ it seems that PFI0 detects the signal as I haven't a timeout, but it doesn't trigger off at the good level.I noticed you posted an earlier question that generated several responses about the valid sources of an analog trigger. Was there a reason you decided to use the PFI0 option over just telling LabVIEW to use Analog channel 0 as the trigger source? At what voltage level are you wanting to trigger?
Also, if you use the Analog Trigger examples in LabVIEW or the DAQ examples for your compiler, do you get better results?

Capturing only one sample after analog trigger on a PXI4461 in Labview SignalExpress

Hi
I capture two waveforms (external excitations) with my PXI446, one on each AI. I use one of them as an analog trigger (rising edge @ some voltage), lets say AI0. I need the value of AI1 at the time (or fixed # of dt's afterwards) when the trigger occurs. I need just that one sample.
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Currently, I use a "subset and resample" step with a very small dt and it seems that it works but I dont like it.
The procedure above is within a conditional loop that collects 100 of these samples (acquire signal triggers 100 times) and produces a statistic of this ensemble (using the Statistics step).
Is there a better way to do this?
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You should post questions about SignalExpress in
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How do I use PFIO as my analog trigger channel?

I'm trying to use PFIO/TRIG1 as a analog trigger signal in a channel scan list. The analog input configuration doesn't seem to recognize this as a analog channel (just 1 to 15. I'm using Labview 6.1, PCI-MIO-16e-4, and the BNC-2090

Voraciousniuser is correct. You set the triggering in the AI_Start VI. We also have some examples on our website:
http://zone.ni.com/devzone/conceptd.nsf/webmain/C7691D8BFAA6881D86256802007B8A9C?opendocument
http://zone.ni.com/devzone/conceptd.nsf/webmain/2AF60E522378449286256815005806D3?opendocument

Start Counter Output on a Analog Trigger in the PCI 6259 Mseries board

Hi,
My question is regarding how to use Analog Triggering to start a counter in the PCI 6259 M-series board.
I have attatched a program here
'Mult_Device_Digital_Analog_Out_on_Analog_Trigger.vi'
and I'll explain my problem regarding this program.
I've tried to include all the details about the program in the documentation for the VI, but what the program
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Problem 1.
I wish to start the whole operation on a analog trigger signal, in the program its the boolean "Line Trigger",
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Thanks.
Shomu
Attachments:
Programs.zip ‏101 KB

Shomu
Admittedly, it might take a little time to find the documentation, but it is there. Also, the error you are getting indicates the proper trigger signals to use. In the help look at the analog Triggering Considerations for E Series, M Series, and S Series.
With that being said the easiest thing to do is to setup an Analog Input task configured to start on an Analog Trigger. Then, setup a digital edge trigger for the Counter task. The signal you are going to want to look for is the Analog Comparison Event. This signal won't show up by default in the list. What you need to do is right click on the trigger source constant or control and select I/O Name Filtering. Then check Include Advanced Terminals. Once you have done this you can select the Analog Comparison Event
StuartG

I'm not able to set Analog Input voltages, etc

ok,
so i have an NI DAQ I/O card (NI PCI 6723, or something to that effect) and i'm trying to configure the channels for Analog Input signals.
when i try to choose any kind of setting for Anolog signal by:
>>drop DAQ Assistant vi onto the block diagram
>>>>choose Analog Input
>>>>>>>Voltage
i get this message "No supported devices found"
i thought since I have the I/O card, i should be able to configure channels for both input/output.
i also have ADAC card (from IOTECH) installed but when i look at MAX, i only see the DAQ card.
i'm really confused at this point. can anyone break things down for me ... what i'm doing wrong?
-r

stuartG,
you were right. so what i'm using for the input is a ADAC 5501MF from IOTECH
following their manual (http://www.iotech.com/productmanuals/adac_lvi.pdf) it says that the ADAC-LVi libraries can be located at "Functions->User Libraries" palette of labview.
does this mean that i have to install the ADAC-LVi driver in LabView->User Libraries directory?
if that's not the case then i don't see why the ADAC-LVi is not showing up in the LabView User Libraries since i've installed the driver correctly (in C\Program File\ADAC )
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Is it possible to start a PCI4472 and a PCI-MIO-16E-1 simultaneously using an analog trigger (with pre-trigger)?

I would like to start several PCI 4472 and a PCI-MIO-16E-1 simultaneously. All boards are connected via a RTSI cable.
My program works fine if I use software trigger, or an analog trigger from a PCI4472 channel. However, the analog trigger works only when I set pre-trigger (or pre-scan) to 0.
Is it possible to start a PCI4472 and a PCI-MIO-16E-1 simultaneously using an analog trigger (with pre-trigger)?
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Hi, Bill
I think it is possible to set more than 38 pre-trigger scans on a single 4472 card. I've done this before. You can verify this by running the Labview example "Acquire N - Multi-Analog Hardware Trig.vi" which comes with LabView.
What I try to do but without success/luck so far is to start data acquisitions of several 4472 cards and a PCI-MIO-16E-1 card using an anlog trigger (with pre-trigger).
Thanks for your help.
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Acquiring 4 channels at 10kHz using PCI-6070E card and Labview 7.0. I need to average a signal that is time-locked to an analog trigger. Is their an available vi to accomplish this?

I am acquiring 4 channels of data, sampling at 10 kHz. I am using a PCI-6070E board. I need to average a biological signal time-locked to an analog trigger that occurs at about 3/second. Is there a vi that will accomplish this?

If you are looking for a way to do a "retriggerable" acquisition, there is a shipping example called Acquire N - Multi-Analog Hardware Trig.vi that accomplishes this. However, please note that this example achieves this effect by reconfiguring the task for each trigger in software. This means there is a delay between reconfigurations. If a trigger signal comes during this reconfiguration, it will be missed. This delay is system dependent on how fast your computer can execute the reconfiguration code. The 6070E does not support hardware retriggerable acquisitions.
However, if you are wanting to acquire continuously and then do some post-acquisition analysis, I couldn't find any examples that accomplish this, but it wouldn't be too hard to build one yourself. Y
ou would probably want to include your trigger signal as an additional input channel. Then once you've acquired all of your data, in software you can scan through the data acquired for the 5th channel and then segment your data according to that signal. I hope this information helps.

Can PCI-6023E support hardware Analog trigger

I try to use the PCI-6023E to do the hardware analog triggering, but it gives me the Error-10403 while I test with the vi example, Aiacquires N Scans Analog Hardware Trig.vi. Is there any way for this board to do the hardware triggering?

Jack,
The PCI-6023E DAQ board only supports digital triggering. You can check all the features of this board in the Data Sheet and Specifications on the Catalog page (see link below)
2002 Catalog - PCI-6023E
http://sine.ni.com/apps/we/nioc.vp?cid=1063〈=US
If you need to perform analog triggering, you have three options:
1) You can simulate it by acquiring continuosly all the signals that you want to monitor including the one that acts as the analog trigger. Compare the value read from this last one with the boundary that is supposed to trigger the acquisition, and when the value read reaches this boundary, you can save or display the data from all your channels.
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You can find detail information on how to set up the digital trigger in Chapter 4>>Timing Connections of the User Manual linked below.
6023E/6024E/6025E User Manual
http://digital.ni.com/manuals.nsf/websearch/0C88F40FFE7F28CD862569AE00574AC1?OpenDocument&node=132100_US
3) Finally, you could get one of our boards that supports analog triggering. The PCI-MIO-16E-4 board has similar specifications that the PCI-6023E, and it has some additional features as well. See link below for more information.
2002 Catalog - PCI-MIO-16E-4
http://sine.ni.com/apps/we/nioc.vp?lang=US&cid=10795
Good luck with your application,
Claudia Lorente
Applications Engineer
National Instruments

Stop trigger, how to specify the analogy trigger channel?

Dear All,
In fact, I am using DAQ2204 cards from ADLINK, which is more or less equivalent to NI E-series muttifuntion board. However, I have some problems with regard to my data acquisition program. Basically, it is about a middle/stop trigger application, which means data acquisition will be starting once the specified analogy channel (for example, channel 0) exceeds a prescribed value.And, data both before and after trigger will be acquired. However, I do not quite understand how to physically make the I/O connection and specify the analog trigger channel and level.
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Hi dragondriver,
I'm providing below links to 2 documents that discuss wiring considerations that are applicable to your device. Hopefully this information is helpful!
E Series User Manual
http://www.ni.com/pdf/manuals/370503k.pdf
Field Wiring and Noise Considerations for Analog Signals
http://www.ni.com/white-paper/3344/en#toc5
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Ex stream to disk analog trigger

Dear NI engineering,
i'm using the example program called "Stream to disk" with a PCI 5112. I was wondering, can i use an analog trigger in place of the software one (like i have done in the vi i have attached here).
This is because i'm trying to synchronize a PCI 5412 and PCI 5112 (by using two different vi).
Moreover i saw also the example from your website called "3784.vi" (i have attached it here), but when i start it, it does not do anything. How come?
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Attachments:
niScope EX Stream to DiskTEST01_analog_trigger.vi ‏49 KB
3784_DOES NOT WORK.vi ‏27 KB

Hi ,
I think that this forum is the same as the SR 7354392 in the mailbox of National Instrument. So I think that I can close this forum and you can follow me in that SR.
Regards,
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Negative analog trigger voltage

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