Insert a DAQ assistant in producer consumer vi

Hi,
I am using a DAQ assistant to receive the measurements in the 10 digital ports.
Hence I use the DAQ assistant icon in the vi s to get these data in to labview.
Now I require it to convert these digital values from DAQ assistant into analog( this i have done )..
Thse analog values are to be taken one at a time for further processing.
I am trying to use this produces consumer loop for it..http://decibel.ni.com/content/docs/DOC-2431
however i dont know where to fit in the daq assistant .
Do i still need the DAQ create channel , sample clock etc?
or do i simply place my daq assistant in the place of the create channelDAQ icon?
thanks for any help..
iam completely confused as to what to do with it!!...
Regards,
ruser

Hi,
Thank you for the suggestions..
i am sending one vi here..
this is my basic vi which gets the data from the DAQ and converts it into data ( angular info) we require ie angular position data of lower and upper encoders. This is a continuous real time prcess, which will stop when we press stop in the vi.
Now i want to take the a set of data (input and output) each, send it to a vi which will receive this set of data; process it and repeat this for the second set of data etc..
I am also attaching the lvm file . which is the data we are saving now.
The first attachment is the vi where i am getting the data.
The second attachment is the lvm data file.
Thanks.. I would appreciate any help here...
ruser.
Attachments:
absolute encoder.vi ‏805 KB
LabVIEW Measurement file.docx ‏17 KB

Similar Messages

Producer Consumer Start Trigger

Short Explanation: I'm using a 3rd party device to send a TTL signal to use as my start trigger in my VI. My cDAQ and modules appear to have the ability to send a start trigger independantly but I have been unable to hunt down how to do this in a producer/consumer system. I do have an idea at the bottom of the long explanation.
Long Explanation:
I'm running a test system that monitors the pressure wave from a hydrogen/oxygen ignition. Components are a cDAQ-9188 with modules 9222 (x3 high speed AI), 9481 (x2 relay), 9402 (x1 I/O Module), 9221 ("Low" Speed AI).
Based upon recommendations in this forum I've placed my DAQ in a producer/consumer architecture.
At this point the system mostly works, I still have a few more things to add for all the information I want to collect. However, it records at high speed and the 9221 and the 9222 modules are synchronized. It has successfully collected good data as of this writing.
When the system starts it will monitor, but not record. I need to fill the test structure with gas to a specific concentration before I ignite/record. When I press the record button I send a TTL signal from the 9402 to my high speed camera and I close a relay on a 9481 which engages a spark system. The spark system takes a variable amount of time to charge and fire so I have a timer that leaves the TTL and the relay active for a half second.
My problem, and it's a small one, comes in with the monitoring system and the synchronization. In order to get the system to synchronize properly I had to generate an external pulse into PFI0 to use as a trigger. I attempted to assign the various clocks available as a start trigger but I ended up with unsynchronized data.
Is there a way to generate a pulse on my 9402 to use as a trigger? It feels silly to me to use an external device when I have something that can generate the signal I need.
In thinking about this post I might have solved my problem, at least in my head. I'm thinking I can move the TTL output VI (which I will eventually change to DAQmx) into the producer loop and move my true/false statements to the consumer loop as a 1D array within my queue to start the record. Probably more to it than that but I can only learn by experimentation right?
Thoughts? Recommendations?
VI attached.
Solved!
Go to Solution.
Attachments:
HUCTA Controls.vi ‏186 KB

You can't generate a pulse with the 9402 itself. The pulse would actually be generated by the 9188. You should create a Counter Output task to generate a pulse train. Try the attached example as a start point to experiment with the counter.
This Vi is for LabVIEW 2013, if you have an older version let me know and I will try to convert it.
Camilo V.
Applications Engineer
National Instruments
www.ni.com/support
Attachments:
Pulse Train Generator.vi ‏18 KB

Producer/consumer question

Hi everyone
I am stucked with a problem using the producer/consumer VI.
My VI continuously acquires data from the DAQ using a producer/consumer VI.
In the maintime, I would like to introduce and save some notes that can help me to identify the acquired data in a separate file without stopping the acquisition.... but I don't know how to do it or modify the producer/consumer scheme.
Any suggestion?
Thanks for the reply
matomato
Solved!
Go to Solution.
Attachments:
ProducerConsumerData_time_Y_Sim_Start_13.vi ‏70 KB

matomato wrote:
Hi Smercurio_fc
The purpose of the code with the Write to Spreadsheet File on the left is to save some comments without stopping the acquisition.
The problem with it is that it only runs once at the beginning of the program.
...The new one should be be to introduce and save his details without stopping the acquisition.
Save where? In this secondary file, or in the measurement file as a comment?
Technically, I don't know how to modify the producer/consumer scheme to introduce the new loop with the case structure maintaining the data acquisition as the main loop.
Hope to have answered your question, if not let me know.
I'm not sure I understand what you are asking. Are you saying you don't know how to add another loop to the code? Or are you saying you don't know how to use the event structure?

DAQ Assist Reading Wrong Voltage

Hello,
I'm using the DAQ Assistant VI to read an analog input voltage from a National Instruments PCI-6221 card. I'm reading the voltage from pin AI0. I supply a voltage directly to this pin from a DC power supply, but the voltage measurement obtained from the DAQ Assistant is incorrect - it seems to be scaled by a factor of about 1/3. For example, if I supply 4 Volts to pin AI0, the DAQ Assist reads 1.43 Volts. I used a multimeter to confirm that the voltage at pin AI0 is in fact 4 Volts, and so I know the problem is with my LabVIEW program and not my power supply.
Here are the steps that lead to my problem:
1. In the block diagram, I insert a DAQ Assistant block.
2. In the Properies of the DAQ Assistant, I select Analog Input->Voltage
3. I select channel ai0
4. I click "test" in order to test the channel
5. The voltage is shown to be 1.43 Volts, even though 4 Volts is being supplied to the pin (this is confirmed with a multimeter).
6. To ensureI click OK to finish configuring the DAQ Assistant. I run the program and plot the voltage. The plot also shows 1.43 Volts.
Does anyone have an idea why this may be occuring. I've spent a good 4 hours trying to diagnose this and haven't found anything.
Thanks,
Abed Alnaif
Solved!
Go to Solution.

Thanks so much for your help. I used MAX, and found out that the issue
is that I had specified differential voltage, but I should have
specified RSE voltage.
However, now I have a different issue: When I apply a voltage to one pin, MAX also shows a voltage on other pins.
For example:
1. I apply a DC voltage of 4V to analog input pin ai0.
2. In MAX->Text Panels..., I select Channel Name = Dev1/ai0 and Input Configuration = RSE
3. I click Start, and the chart shows the correct voltage (4V)
4. I change the Channel Name to Dev1/ai1and Input Configuration = RSE
5. The chart shows a noisy voltage reading between 1.45 and 1.5 V, even though no voltage is applied to pin ai1
6. When I change the voltage on pin ai0 to 2V, the voltage reading on pin ai1 changes to 0.63V
7. Using my multimeter, I confirm that there is in fact 2V on pin ai0 and 0V on pin ai1
Does anyone know why applying a voltage to pin ai0 causes a voltage reading on pin ai1?

Producer Consumer Subpanels, User events and DAQ

Hello All,
I am working on a Producer Consumer application and have beed looking at subpanels for user navigation. The application needs to be capable of responding to user generated events but also manage data received from attached data acquisition and control hardware. This is a 2 part question.
I need to implement about 15 screens in this application and have started integrating subpanels. I need to be able to navigate from one subpanel vi to another using subvi buttons but dont understand how to build this functionality. Can I build functionlaity so that when I click on a subpanel loaded vi's button it will load the vi referenced by that button and the original dissappears.
I have a 3 loop producer event template consisting of (1)data acquisition producer, (2) user event producer and (3) consumer loop but theres not much detail, are there any reasonable templates out there? I have seen the data- consumer and user-consumer but no mix of all 3.
Advice appreciated
Chris

I use subpanels to host my display vi's and control them dynamically. I would have a loop or vi process that manages your subpanel. You could use user events, queues or notifiers to send messages to this subpanel manager to perform the basic functions such as loading a vi into a subpanel, removing a vi from subpanel (you can remove and stop the vi or keep the vi running in the background or even make it a floating vi.) A subpanel button can create a local event which in turn could trigger a user event or message to the subpanel manager. I have attached my subpanel manager to give you some ideas...
Attachments:
Subpanel Manager.vi ‏39 KB

Instr. and DAQ Assistants - Time to take off the training wheels?

Hi everyone,
I have written a control system program using a producer/consumer with state machine architecture - textbook LabVIEW beginner intermediate.
In the producer, I have 6 different DAQ assistants taking AI and DI data from PXI mounted data acquisiton cards and two Instr. Assistants taking data from PXI serial ports. In the consumer, I have a similar situation. There are 7 DAQ assistants sending digital and analog requests to 3 different PXI chassis and one Instr. asssistant sending requests to a PXI serial port.
Is this frowned upon? Would any of you pros call this a finished job if it is still bound with Assistants? I have looked at the code involved in making these assistants into LabVIEW code (writing them out, so to speak), but it is complex and I haven't been able to put in the time to learn all of the different DAQmx and VISA functions and subVI's.
However, I have some difficulties that arise when, for instance, a component that is monitored/written to by a serial port is turned to manual control and the assistant times out. It times out the entire control system, which is not desirable. Is the fix in error handling, or getting rid of the assistants altogether?
Any responses are appreciated - even if you are the bearer of bad news!
Brad

Hi Brad,
Using DAQ assistants in a loop does come with some overhead. However if you are acquiring at relatively low speeds and do not want to use the DAQmx VIs, it shouldn't be a problem. Though programming using DAQmx VIs might look somewhat intimidating it follows a general priciple common to most I/O in LabVIEW. You open/create a channel, configure it, read or write and then close it. Generally, only the read or write VIs will be in the loop. So doing the creation and configuration every iteration of the loop is the overhead.
I am not entirely sure what is timing out and what you are doing to cause a time out. There are two ways to generally fix time out errors. One, as you pointed out, is to handle the error. You can do this by unbundling the cluster to look at the error code, if it is a time out error, you can reset the error cluster.
The other solution is to increase the timeout for the DAQ assistant. (Wire the time (in seconds) you want it to wait, to the timeout input of the DAQ Assistant).
Cheers
Malay Duggar
NI

What is ment by 'producer/consumer approach'?

What is ment by 'producer/consumer approach'?How would I implement into the program shown in the screenshot below?
Cheers
Sam
Attachments:
wind5.png ‏91 KB

In your program the DAQ and IO assistances would be the producers, and the filewriting would be the consumer.
Look here for more info.

DAQ Assist Continuos High Speed Display

I am using the DAQ Assist to read in voltage data and display it as a scrolling chart. When I set it to take "N Samples" it works well, but wont display that data until the N samples have been collected. When I switch it to a continuos mode and set it to take 1 sample buffer at the same rate (20kHz) it actually samples much slower. Any suggestions about how to get a continuous chart that still shows the the data at full speed?
Thanks

The DAQ assistant, while it is great for getting a quick and dirty DAQ task up and running, isn't really designed for high speed data acquisition with precise control. You will likely need to use the lower level DAQmx functions. Start a task, acquire chunks of data in a loop, end the task. You may need to pass the data off to a parallel loop for data processing, display, or logging using a producer/consumer design architecture. Take a look at the DAQmx examples in the example finder.
If you right click on your DAQ assistant and select Open Front Panel, it will turn the Express VI into a subVI that you can open and see how the underlying DAQmx code works.
It may even be a matter of selecting continuous samples in your DAQ assistant, a small number of samples to read, have it in a loop that iterates enough times until you have collected your larger number of samples.

Setting the interchannel delay via DAQ assistant

I have explored all the options provided as I double clicked on the DAQ assistant. But there seems nowhere to set the interchannel delay. I wonder if the interchannel delay can still be set even when I'm using the DAQ assistant?

Hi hlseck,
In DAQmx, the interchannel delay is also known as the Convert Clock. You cannot set the Convert Clock within the DAQ Assistant. The best solution is to set up your DAQ Assistant, right-click the DAQ Assistant and select Generate NI-DAQmx Code. Then, insert a DAQmx Timing Property Node before your DAQmx Start Task to set the Convert Clock rate.
If you are using NI-DAQmx 7.4 or later, you can be assured that the readings are set to
scan between channels as quickly as the hardware can physically produce
accurate readings. If you would like to slow down this behavior (i.e.
increase the interchannel delay) you can set the Convert Clock rate
manually in a the DAQmx Timing Property Node using the Convert Rate
property:
For more information on how the DAQmx driver handles the Convert Clock, or interchannel delay, please see this KnowledgeBase.
Regards,
Erik

How can I programmatically change the voltage range settings in a DAQ Assistant

Hi,
First post here.
I need to be able to change the voltage range properties of a daqmx DAQ Assistant based on user input. My hardware, an SCXI-1102C does not allow changing this property on a running task, so I'd like to either set the analog input voltage range before the DAQ Assistant activates, or pause the DAQ Assistant immediately after it starts, set the values and then resume.
I don't know how to edit the task ahead of time because the DAQ assistant creates the task when it runs, and there is no task before that.
In the attached picture, I have a conditional section, set to run only if the while loop iteration is 0. I take the task from the Daq assistant, send it to a stop task vi, set the property, and then send the task on to the start task vi. I can watch it run with the debug light on, and everything seems to work correctly, but on the second (and all the other) iteration of the loop, I read out AI.Max and it seems like the DAQ Assistant has re set it back to 5V. Can anyone see what is going wrong here?
BTW, this is continuous acquisition and the code does not produce error messages when it runs.
I did come across a similar question that someone posted here back in 2006, but his question was specifically aimed at a Labview API (VB, I think), and not an actual G solution.
Attached are the actual vi in question and a png image of the block diagram.
Thanks!
Ruby K
Solved!
Go to Solution.
Attachments:
Labview_question.PNG ‏14 KB
Sample_AIV.vi ‏91 KB

First, if you want to start getting beyond the basics with DAQ, you are going to have to stop using the DAQ assistant and do it with lower level DAQmx VI's. There are hundreds of examples in the example finder. You can even right click on the DAQ assistant and select open front panel. That will create a subVI that you can open and see what is going on behind the scenes. Do it. I think you'll find the DAQ task is being recreated on each (though I'm not 100% of how the settings are established or maintained in each section of that subVI).
The second problem is you have a bit of a race condition on iteration 0. Those two DAQ property nodes are running at the same time. So when you read the AI.Max, it may be happening before or after the AI.Max is set in your case structure.
Third, make sure you wire up your error wires.

Producer consumer error 200279

Hello,
So I’m about to go crazy and hoping someone can help me here. I’m writing a program that controls a motor and using a producer/consumer method to write the data at 10,000 intervals a second. I’ve read through multiple examples and I don’t see what I’m missing. I’m trying to record 18 different readings from a DAQ 9178, 3 readings for voltage module NI 9205, 1 reading for current module Ni 9203, 2 readings for accelerometer module Ni 9234 and 12 readings for temperature module 9213. Every time I run the program I keep getting the error message 200279 and it states that it’s trying to read samples that no longer exist. It advised me to increase the buffer rate. So I did as it suggested in multiple ways and the error messages keeps showing up. I’ve also shut down the computer, exited and restarted Labview several times and none of this worked. I have included the a picture file below. Where the problem is, is in the producer loop and the error is shown coming out of the DAQ error indicator. One idea I had but I’m unsure how to approach it is to somehow mean the data coming out of the DAQ to reduce what’s getting to the buffer. If anyone knows how to fix this problem please explain it in detail (I mean talk to me like I’m stupid) cause I’ve been stuck on this problem for almost two weeks now. Thank you in advance to anyone who can help.
SteelTiki
Solved!
Go to Solution.

The DAQ error isn't related to your choice of architecture, although your implementation of it might be hurting you. It's almost impossible to follow what's going on in your diagram because you have wires running in many directions (try to keep data flowing from left to right), there are local variables all over the place (almost definitely not needed), and there's a lot of code that's not in the image or is hidden in another frame of the sequence. Normally one would not have the event structure as the consumer loop (as you've done), and it's generally not a good idea to have multiple event structure in the same VI (with rare exceptions usually involving user events). It might not solve your problem but it would be worth taking the time to clean up your diagram. Eliminate sequence structures and local variables as much as possible, move some code into subVIs, and straighten out your wires.
As for the DAQ error: the DAQ board is reading data into a circular buffer, and you're not reading it fast enough, so samples are being overwritten. The reason you're not reading it fast enough is because you only read a single sample at a time (the DAQmx Read is configured for 1 sample on multiple channels) but you say you're acquiring 10,000 samples/second. Since your loop won't run 10,000 times per second, you're not reading all the data, which causes the error. Try configuring the DAQmx Read for multiple samples.

Producer/Consumer Design Pattern + DAQmx + Event Structure

Dear community users,
at the moment I try to implement the Producer/Consumer Design Pattern into my current project. For this purpose I am trying to make a "minimal-example" in which I use the Producer/Consumer Design Pattern for the data acquisition and analysis (display in GraphXY, calculation etc..) process. In the Producer Loop I perform the data readings via DAQmxRead.VI and in the Consumer Loop, in this example only, I display the data in a GraphXY. At the same time I want to control the data acquisition via an Event Structure, for example Start Measurement/Stop Measurement Buttons. To configure the measurement time, for example if the user only wants to measure 150 sec, I use the Time Out Event of the Event Structure. This is a technique which is often used, when data acquisition and Event Structures are used at the same time (Excuse me if this is wrong!). Due to understand the Producer/Consumer Design Pattern I looked up in the Template\Framework of LabVIEW.
In the attachment you will find my "minimal-example", which -sadly-, not working. What should I do ?
Thank you.
Best regards,
tugrul öztürk
Attachments:
daqEngine_PCP.vi ‏35 KB

Your VI will never stop due to the Ok Button that stops the producer loop is read OUTSIDE of the loop. Add an event case for it.
Move the Start and the Ok Button inside of their respective event cases. This will allow the latch to reset when they are read.
Change the Ok Button to a stop button.
Use a Greater Or Equal instead of Equal for the measurement time comparison. What if somebody randomly changes it to 0 on you? Again, you will never stop.
Is the DAQ only supposed to read for "Measurement Time". Right now, it constantly reads. So if you don't use the DAQmx Read, you will get a buffer overflow error. You need to put the DAQmx Start Task inside of the Start event case and then the Stop DAQmx Task inside of the Timeout event case when the measurement time is exceeded. You should also perform the read regardless inside of the Timeout event case.
I HATE telling the consumer loop to stop by destroying the queue. You can look data that way. Instead, send something an empty array. In the consumer, check for an empty array. If it is empty, stop. Destroy the queue only AFTER BOTH LOOPS HAVE COMPLETED.
You should also report your errors in some way. Simple Error Handler at the minimum.
Since you are using Continous Samples, don't limit the buffer. Leave the Samples per Channel unwired on the DAQmx Timing VI.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Timed structure for output in producer consumer data acquisition

Hello LabVIEW community,
I have a bit of a problem. I am writing a program that is primarily for data aquisition but has a few control features as well. I need the program to aquire and write several channels of data at a relitively high speed. The program does this fine ( in the top 3 loops fo the program). I need the program to also send a seires of two output signals in response to a particular condition. When a certain channel registers a value of above a specified number, I need an output channel to write an anologue signal for 225 seconds and then a signal of a differnt value to the same channel untill the condition occurs again (not for several hours).
I put this action in a timed structure inside of a case structure. The case structure and timed structure are inside of a second consumer loop. I have no idea if this is ligitimate. This event takes much longer than any of the other loops which run at 1 or 2 seconds. When I exicute the program with "highlight exexutuion" this longer (case/ timed ) loop never executes. I asssume this has to do with the mismatch in time scales of this loop and the other loops in the program. I also didn't really understand the help information on timed structures, so its possible that I just need better/ different inputs to the timed stuctures.
If anyone can see any obvious problem in the code or suggest a better way to do the output function I would really appreciate the help. My code is attached.
Thanks,
Jo

I can't figure out how to fix your code, but I can point out the things I see wrong with it.
1. You are dequeueing elements from the same queue in the same loop. In one you are not taking the element, and in parallel, you are taking an element. I see that in your bottom two loops. Why? That code won't execute until the queue gets two elements in it. And which dequeue gets it first and which gets it second is an arbitrary race condition. So there is no certainly of order (first 4 vs. last 4 currents in the one loop), or which gets kept and which gets discarded (in the other loop.)
2. You are creating and/or clearing DAQ tasks in every loop iteration. Tasks should be created before a loop, used inside the loop (read or write), then cleared once the loop is done. Anything else is wasteful, time consuming, and could lead you to run out of resources.
3. You are using the STOP function which is pretty much like hitting the abort button on the toolbar. No program should ever stop that way. All loops should exit gracefully.
4. You have a data dependncy between your bottom two loops because of the boolean wire running from one to the other. That bottom loop will only run once (if the value is True), or run forever (if the value is false).
5. Use of the dynamic datatype. You are taking waveforms, converting them to a blue wire, then coercing them into another datatype such as just displaying a scalar in an indicator. A lot of unnecessary conversions there.
6. Your thermometer indicators have a digital display you can make visible. Then you won't need the separate numeric indicator to display the value.
7. For loop that runs only 1 time because of the constant wired to the N terminal. Get rid of the For Loop.
8. Check your spelling. The word "Temperatures" on the graph, and one instance of "distillate" is missing an "l".
Until all of these problems are fixed, it is not worth talking about timing of timed structures. Some of these problems were discussed in your other thread. http://forums.ni.com/t5/LabVIEW/producer-consumer-missing-channels/m-p/3159757#M911255 But now it seems like you've made things even more complicated without fixing the basic problems.

State machine VS producer consumer architecture - Time Analysis

After learning various methods to program efficiently and learn how to use SM and Producer consumer. I built a program to control stepper motor in both these techniques.
Here is the RESULT. As we can see a simple state machine without any complicated producer consumer technique performs faster than the second one.
I am not sure which is still the best based on performance and optimization. Please advise which one should I keep and why.
Abhilash S Nair
Research Assistant @ Photonic Devices and Systems lab
[ LabView professional Development System - Version 11.0 - 32-bit ]
LabView Gear:
1. NI PXI-7951R & NI 5761
2. The Imaging Source USB 3.0 monochrome camera with trigger : DMK 23UM021
OPERATING SYSTEM - [ MS windows 7 Home Premium 64-bit SP-1 ]
CPU - [Intel Core i7-2600 CPU @ 3.40Ghz ]
MEMORY - [ 16.0 GB RAM ]
GPU - [ NVIDIA GeForce GT 530 ]

This is with state machine alone
Abhilash S Nair
Research Assistant @ Photonic Devices and Systems lab
[ LabView professional Development System - Version 11.0 - 32-bit ]
LabView Gear:
1. NI PXI-7951R & NI 5761
2. The Imaging Source USB 3.0 monochrome camera with trigger : DMK 23UM021
OPERATING SYSTEM - [ MS windows 7 Home Premium 64-bit SP-1 ]
CPU - [Intel Core i7-2600 CPU @ 3.40Ghz ]
MEMORY - [ 16.0 GB RAM ]
GPU - [ NVIDIA GeForce GT 530 ]
Attachments:
Control 1.ctl ‏6 KB
Control 2.ctl ‏6 KB
Motor-UNI_Directiona Dev 3-TIME_ANALYSIS-2.vi ‏54 KB

Installation of Lab view 8.20, DAQ Assistant has disappeared & Instrument I/O Assistant cant be used

After upgrading to Lab view 8.20 and on a 8.20 new install I
notes’ that
DAQ Assistant has disappeared from the tool pallet completely.
Also that Instrument I/O Assistant cant be used or
configured and produces an error
“NI Measurement & Automation Explorer or the Instrument
I/O Assistant is not correctly installed. Please install these from the Driver
CD”
I have checked both of these and all parts are fully installed
and I cant fined what part of the Full version of Labview would course this
problem.
Would a completely new installation with default settings
clear the problem, what has coursed these tools to be not avalible.

Hi Trevor
You need to load on the Drivers for DAQmx, if you have a CD you can load them on from there otherwise the link to download NIDAQmx 8.3 is:
http://digital.ni.com/softlib.nsf/websearch/7feaee6a4b4aa836862571c00064e6ca
There is a order in which you must load things on for everything to work correctly,
LabVIEW --->> Modules & Toolkits --->> Drivers
This should solve your issue
YatinM
NIUK

Insert a DAQ assistant in producer consumer vi

Similar Messages

Maybe you are looking for