quadrature encoder synchronize the sample

Using a USB-6251 housing measure a quadrature encoder, I will determine the angle that external discrete changes state.  I tried to connect the unobtrusive to a DIO of entry and using code CVI PC read the angle of the encoder, when the state change occurs.  The problem is the lag time of the PC code that adds up to 4 degrees (with a variability) to the measured angle.  An ideal solution would be to trigger a measure in a buffer in the USB-6251 housing when the State of the discrete changes, then read the value in the PC at a later date.  Is this possible with the USB-6251 housing?

Thanks Adam,.

I solved my problem by using this idea with the addition of the use of sampling buffered and discreet as a trigger.  Engaging the material task also seems to be a good idea, but may not be required.

The installation code looks like this:

Start a way to encode on the counter 1 to control the angle of the label sensor PNP edges
status = DAQmxCreateTask ("PNP Rising edges", & pnpTaskHandle);

strcpy (chanString, devName);
strcat (chanString, "/ ctr1 ');

status = DAQmxCreateCIAngEncoderChan (pnpTaskHandle, chanString, "", DAQmx_Val_X4, 1, 0, DAQmx_Val_AHighBHigh)

DAQmx_Val_Degrees, 4096, 0,0, "");
sprintf (chanString, "/");
strcat (chanString, devName);
strcat (chanString, "/ PFI1");
status = DAQmxCfgSampClkTiming (pnpTaskHandle, chanString, 1000000, DAQmx_Val_Rising, DAQmx_Val_ContSamps, 10)

(0000);
If (status<>
DAQmxGetErrorString (status, errString, 1000);
DAQmxTaskControl (pnpTaskHandle, DAQmx_Val_Task_Commit);
 
Start the task
status = DAQmxStartTask (pnpTaskHandle);
angleTaskStarted = 1;

Read the value of looks like this:

status = DAQmxReadCounterF64 (npnTaskHandle, DAQmx_Val_Auto, 0, npnEdgeArray, 1000, & npnSampsRead, 0);

Tags: NI Software

Similar Questions

  • VI quadrature encoder does not work after programming of FPGA

    I'm rather new on the MyRIO, and I work on the motor of the MyRIO and read control in a quadrature encoder at the same time. Programmed individually, the two pieces of work at Marvel, but once I have combine them and try programming, control of motors not to not work signals, but the reader encoder does not work. I use the Express VI for the LabVIEW quadrature encoder reader, and I produce four stepper motors signals using FPGA.

    It seems as if the encoder is disabled when I program the FPGA with my code, because if I have two parallel loops, one for the reader encoder and the control of step motors, if I stop the loop of step motors, the encoder works immediately.

    Is there something simple that I'm missing?  Any suggestions would be greatly appreciated!

    Thank you

    Enan

    I realize now that my last answer could have been confused and not useful to someone else who may come across the same problems later.

    Here is how I solved the problem I've had:

    I had to derive Boolean expressions for an encoder quadrature (essentially to create my own) and then used the outputs (UP, DOWN) to increment/decrement a counter using the conditional statements. Then, I stored the value of direction in a flip flop implemented using two conditional statements of T/F in series and connected to a shift on the edge of the loop register.

    It was all able to be implemented in a single cycle timed Loop, and then I managed to place in the same loop that I used to control stepper motor.

    In this way, I could have a VI collected in a Bitfile and could be programmed to the FPGA.

    Hope this is clearer!

    Enan

  • Problems of synchronization of the sample clock with a frequency of a PXI-6229 counter!

    Hi all, I'm having some problems with the synchronization of a frequency meter connected to a liquid flow meter (sensor only have 1 open collector output) with the sample of a PXI-6229 map clock. Someone there willing to give me a little help here would be appreciated?

    The problem is that the reading of the meter in the whole loop blocks until the time-out period.

    Suggestions for an alternative approach would be too good...

    Source code attached.

    BR,

    / Roger

    It sorted another way!

  • Synchronize the pci-6254 and cDAQ-9174

    Dear all,

    I hope you enjoy!

    I intend to synchronize two cDAQ-9174 chassis for an application where I need to acquire data of 8-Thermocouple, voltage 3, 1-Full bridge (strain gauge) and channel 2-meter at the same time. This enforcement action is based encoder (quadrature with 1024 ticks per round) and I need to acquire data very fast and synchronized in all channels!

    I bought the material and I'm going to set up 3-voltage channels in NOR-9221, Thermocouples-4-NOR-9211, 1 strain of NOR-9237 and 2-meter gauge in NOR-9401 first cDAQ-9174 chassis Modules. I will then put remaining Thermocouples-4 in the second cDAQ-9174 chassis.

    The question is whether it will work?

    If Yes! Then, kindly help me on how to have synchronized it data from these two cDAQ-9174 chassis with all such modules as mentioned above?

    I hope someone can help me with that and can guide me to do this task! I'm using Labview 2009 with NOR-DAQmx 2009

    Kind regards!

    Tajim!

    A few comments after looking at your code:

    I don't understand what you're doing with cancel in the task of counter.

    You try to use the encoder as your sample clock?  You can do it for the module 9221 and NI 9211, but it will not work with the NI 9237 as I mentioned above.  You can move the NI 9237 in a separate task and from there, you have a few options depending on how you want to synchronize.

    How many times you expect to get your clock on cDAQ2Mod3/PFI0?

  • Using more 4 for MyRIO quadrature encoder inputs

    Hello

    I am doing a project where I need to drive 6 motors, each with feedback from encoder quadrature to control the position.

    Currently, I use the VI MyRIO encoder, but there is a limit to 4 encoders. What is the best way to read 6 encoders simultaneously with the MyRIO?

    Thank you

    Timothy

    If you must change the FPGA myRIO personality you have a few options.

    The best option is to start with the FPGA myRIO sample project, add and delete components according to the needs and then build your bitfile.  No registry (LV FPGA control / indicators) you do not change will still work with the Advanced IO screws and screw Express.  To use the new bitfile (FPGA personality) you must update the Reference of VI FPGA opened in myRIO Open.vi v1.1 (LabVIEW 2013\vi.lib\myRIO\Common\Instrument Driver Framework\myRIO v1.0\myRIO v1.1 Open.vi).

    After having done all this time, you use an Express VI myRIO or Advanced IO VI it will use your custom bitfile.  All peripheral channels that you left in place will continue to work.  You have deleted all channels will always appear in the screws, but will not work (they will probably throw errors when running) and all new channels that you added appear in the screw .  New channels, you will need to use FPGA read / write nodes for read and write configuration data and register you created in the FPGA personality.  These changes will persist on this computer until you change the Reference of VI open FPGA to the bitfile original.

    Let us know if you have any questions about all of this.

    Thank you!

    -Sam K

    Hacker of LabVIEW

    Join us / follow theGroup of pirates of LabVIEW on google +

  • create a spectrum of the order from scratch (i.e. get a fft-based on the position of the same time deductions in the sample data)

    Hello people,

    THAT THE QUESTION PERTAINS TO:

    I play on 2 parameters of a system based on the sampling time: Rotary position and vibration (accelerometer g increments).  I want to take a fft based on the post to create a spectrum of the amplitude-phase speed order in / s.  To do this, perform the following:

    1 integrate (and scale) g vibration signal in the / s (SVT Integration.vi)

    2 signal sampled vibration resample the same time at an angle similarly charged signal (ma-resample unevenly sampled input (linear interpolation) .vi)

    THE QUESTION:

    Order in which operations should be carried out, integrate then resample or vice versa?  I didn't order would be important, but using the same set of data, the results are radically different.

    OR ORDER ANALYSIS 2.0 TOOLSET:

    I have the NO order Analysis Toolset 2.0, but I could not find a way to get the speed profile generation live to work with signals of position encoder DAQmx (via pxi-6602) quadrature.  In addition, it seems that I have to specify all the commands I'm interested to watch, which I don't really know at this point (I want to see all available commands) so I decided to do my own fft based on the post to get a spectrum of the order.

    Any help is greatly appreciated.

    Chris

    The order is to integrate the time domain of first - creating a speed channel.  You now have a new channel of data.  In general I would put this in the same table of waveform with waves of acceleration time.

    Then re - sample your acceleration and/or your speed signals, and then you can calculate the spectrum of the order.

  • Synchronize book samples IBook?

    I can sync iBooks purchased on all my devices but iBook samples

    does not synchronize. It is built in iBooks property or a mistake on my part.

    Indicators are defined the same as those purchased books.

    The samples are not synchronized between devices

  • reading of the sampling frequency of the NI9862

    Hi all

    I use a DAQ chassis with modules 9205 (analog input) and 9862 (NOR-XNET CAN).

    I have a program to synchronize the modules for acqustion based on the attached example. My question is how to determine the rate at which data comes the 9862?

    It seems to be double the rate of the 9205 when I set the sampling rate for the 9205 to 500 Hz.

    Is there a property node or a method that I can use to find the rate? I looked in the manual, and it gives no information.

    Thank you

    Griff

    griff32,

    Baud rate XNET CAN occur in your database. You can also check using a property node. In the example, in the XNET Session property node, you can develop, select the Interface > baud rate. You can do a right click on it and change it to read and son in an indicator.

    Alternatively, you can write to this property node to replace the transmission speed in the database. Baud rate must be compatible with the speed of your network. It also has a max of 1 mbit/s. If you want both to acquire the same amount of data, I would recommend changes in the rate of the analog input task or samples to read through.

  • Change the sample DAQmx and Terminal configuration mode

    Hello

    I'm studying 'Timing and synchronization features of NOR-DAQmx' from the following link,.

    http://zone.NI.com/DevZone/CDA/tut/p/ID/4322

    Could someone tell me how to Figure 2, Terminal configuration entry in the part "DAQmx virtual channel creat? Shoud I double-click on the icon to change it? Or there is some way that I can show it in the block as the sample mode diagram in the DAQmx part?

    How can another question, in the DAQmx calendar part, I put "Continous Samples" here? It comes from the function palette? Thank you.

    Hi Oly,
    To make the configuration of senior year to enter the channel 'DAQmx create' you will need to create a constant or control over this VI either.  When you hover over a VI, as the VI "DAQmx Create Channel", you will notice that the dots appear around the edge of the square.  "" When you roll your mouse over these points, you mouse pointer will appear a coil of cable/wire how you can right click your mouse and select 'Create' constant ' or 'create' control '.  If you create a control, you have a user control in your front, where as if you create a constant, you will have a drop-down list in your block diagram.
     
    It goes the same for continuous samples, simply hover over the VI, right-click on the corresponding 'point' and select this option to create a constant.
     
    In case my instructions are unclear, that I have attached pictures of how to go about doing this, the first is to show 'points' I speak around the VI and the second picture shows the possibility to choose after you right-click on the point.
     
    Good programming!
    aNIta B
    Technical sales engineer
    National Instruments

  • Synchronize the ctr1 at ctr0 (generate outputs freq) via the signal of export

    I need help to configure the output channels of meter on my card pxi-6723. Here's what I'm trying to do:

    -have the possibility to synchronize the ctr1 exit toward ctr0. Note: ctr1 must begin on edge increase or decrease output ctr0.

    -be able to change idle, freq. etc for each of these outputs

    A sample that I worked on is attached. It works except the ctr1 output is trolling by cycles of 1 to 1.5 (according to a State of rest, edge selections). This delay is due to me having to put the slave (ctr1) task run after the masters. Note: The reason for this was the task of enforcement of crt0 (master) was the origin of the false triggers when exporting the trigger signal.

    Its there a way of software trigger ctr0 OR delay its release until both (ctr0 & ctr1) 'perform tasks"have been launched?

    Hi groz,.

    I have not tried, but I expect the following sequence to prevent false triggers:

    DAQmx control Task (ctr0 task, Commit)

    DAQmx Start (task ctr1)

    DAQmx Start (ctr0 task)

    Principal ctr0 has it on its state of rest.

    Also, I think you can do this trip without using a PXI_Trig line. To Start.DigEdge.Src the ctr1 task, specify "Ctr0InternalOutput". (To make the Terminal Ctr0InternalOutput appear in a Terminal of DAQmx e/s constant, right click on the constant, select "I/o name of filtering...) ("and put a check mark next to"Include the advanced terminals").

    Brad

  • Programming of FPGA for motor control using downloadable IP cores for free for PWM and interfacing Quadrature encoder

    Hello

    I have a cRIO-9014 with a NI9505 DC brushed servo drive module and I would like to program the FPGA to PWM and encoder, quadrature, interfacing using the functions of intellectual property intellectual property mentioned in "CompactRIO Motor Control Basics Tutorial":

    DX of encoder quadrature method (FPGA, using SCTL) .vi

    Pulse Width Modulation (FPGA, using SCTL) .vi

    I did a search at ni.com/ipnet but I could not find them.

    Where can I find free downloadable IP cores for the blocks of PWM and encoder to include them in my interface FPGA program?

    Thanking you in advance,

    Manual

    Found by myself (google search!) to:

    https://lumen.NI.com/nicif/us/codepowelecguide/content.XHTML

  • How to synchronize the start of IT and relaxation the Scan list (DAQmx Switch)

    Hello

    I want to measure samples of N to the AI0 of Council NI PXI 4461. The measurement starts on a rising edge of a digital triggering provided to the PFI0 of the same Board. The measure is configured with samples of N/2 pretrigged. So far, everything is under control...

    Using an NI PXI 2567 Board, the signal applied at the entrance the 4461 (AI0) switches between a V2 and V1 signal. I would like to synchronize the switch between the two signals with the trigger signal applied to the input of the PFI0 Governing Council 4461. In order to obtain samples of N/2 of V1 and V2 samples N/2. Synchronization of 1 to 5 ms would suffice!

    My question is how to synchronize the start of acquisition of AI pretrigged of 4461 with the switch control given by the Council of 2567?

    Thank you in advance for your help...

    PS: the configuration of the system is:

    -LabView 8.5

    -Chassis PXI-1044

    PXI-4461 on slot 2

    Module 4-slot PXI-2567

    Hi Frederic,.

    I came back to this recently and used the following examples to run the desired synchronization.

    PXI-4461: Acq & graph tension-Int Clk - dig Start & Ref .vi

    Samples per channel = 1000

    Rate (Hz) = 10000.00

    Start the trigger Source = / [name of the instrument DAQmx] / PXI_Trig0

    Onboard start = fall

    Reference Source Trigger = DAQmx Device Name] / PXI_Trig0

    Reference edge = fall

    Trigger samples = Variable (100, 500, 900)

    PXI-2567: Switch Scaning-SW Trigger.vi

    Advance the output terminal full = / [name of the instrument DAQmx] / PXI_Trig0

    Scan list = / [name of the instrument DAQmx] / ch0-> com0.

    Scan list = / [name of the instrument DAQmx] / ch1-> com1;

    Hardware configuration:

    The PXI-2567 module controls an external relay that switches between the voltage of 5 V on ch0 and ch1 0 V.

    The PXI-4461 connects to the COM of the external relay and therefore reads 5V when ch0 is connected; 0 v when ch1 is connected.

    Procedure: The above examples are used in the following procedure.

    1. run the PXI-4461 VI.  A start trigger (falling edge) is necessary to start collecting samples before firing.

    2. launch the module, PXI - 2567 VI.  When ch0 is initially (and immediately) on com0, a trigger is sent to PXI_Trig0.  The PXI-4461 will begin to acquire samples before firing.

    3. - click on the "Connect to the next" button on the front of the PXI - 2567 VI module.  This sends a trigger to entry software for the PXI-2567 module and the transitions of the scan for ch1-> com1 list.  Once the PXI-2567 module remains (debounced), advanced complete relaxation is sent on PXI_Trig0 for the PXI-4461.  The PXI-4461 will begin to acquire samples after outbreak.

    Note: Instead of the trigger of the software entry, an external input trigger can be used (e.g. PXI_Trig1).

    Results:

    > Before instant release of samples = 100

    Delay is caused by the time of actuation of external relay.

    > Before instant release of samples = 500

    Delay is caused by the time of actuation of external relay.

    > Before instant release of samples = 900

    Delay is caused by the time of actuation of external relay.

    I hope that the attached screws and the explanation above helps you and/or other customers who have this problem.

    Best regards

    Chad Erickson

    Switch Product Support Engineer

    NOR - USA

  • Buffer the output AO, refresh rate is different from the sample clock frequency

    Hello

    I am an AO output in the buffer using a single channel. I have a stamp with a ripple of 200000 points with a triangular waves of a 1000pts each repeated 200 times. If I want a frequency of 1 Hz, I simply update this waveform 1000pts and if I wanted to 5 Hz, then 5000pts and so on. But there is some frequency that I won't be able to use like the refresh rate (the number of samples that I ask to update) is different from the sample clock frequency, which makes synchronization with the other difficult to trigger (incomplete cycle).  Frequency 3 Hz (update 3000pts), as (update 7000pts) 7, 6 Hz (update 6000pts), 9 (update 9000pts)... 11Hz at 15 Hz and is not valid in the sense that the refresh rate is different from the sample clock frequency. That makes a whole lot of inaccessible CONFIGURED!  Can someone tell me what determines the banned frequency?  Is this something to do with the material?

    concerning

    One thing you can try is to change the number of samples per cycle. This cannot give the precise frequency accurately, but can reduce the average error.

    120 Hz, the error is currently about 400 parts per million (ppm). The accuracy of the time base is 50 ppm, then this error is less than 10 times the inherent error due to the time base.

    Consider this configuration: the closest nominal sampling you rate, you can get is 120048 Hz (1000 samples per cycle at 120 Hz). If your buffer contains 1200 samples per cycle, 100 copies of it would produce 1 second of data to 120,048 Hz. But if the buffer contained an average of 1200,48 useful Samper by cycle, you get the exact frequency.  Of course getting 0.48 of a sample is delicate. But the kind of feasible. If you use 48 cycles in the 1201 samples per cycle and the cycles of 52 to 1,200 samples per cycle, the total number of samples per second = 120048. Average frequency will be exactly what you want. Instantly, the frequency is slightly higher or lower than the exact value.  By an alternation of 1200, 1201, 1200, 1201... 1201, 1200 100 cycles that the Jig is fast.  If you group all 1200s whole and all 1201 s frequency hopping may be more sensitive.  If this kind of jitter is acceptable depends strongly on what you do with the release.

    This technique is used in some systems of frequency synthesizer.

    Lynn

  • Configuration of input DAQmx terminal and choice of the sample mode

    Hello

    I'm studying 'Timing and synchronization features of NOR-DAQmx' from the following link,.

    http://zone.NI.com/DevZone/CDA/tut/p/ID/4322

    Pourrait
    someone tell me how to Figure 2, input terminal in configuration
    the part "DAQmx virtual channel creat? Shoud I double-click
    the icon to change it? Or there is a way I can show in the
    Block diagram as the sample in the DAQmx part mode?

    One
    more question, in the DAQmx calendar part, how can I put continues «»
    "" "Samples" here? It comes from the function palette? Thank you.

    No, you do not double click on the icon to change it. To answer these two questions, just right click on the device and select ' Create > constant "."

    It comes to LabVIEW basics. I would recommend that you study only here before you start experimenting with DAQmx.

  • Synchronize the case structure with enum update

    Hi, I created a control enum initially with the "First" and "Second" values. In the block diagram, I created a node of this enum control property and it is connected to a box structure. The structure of business allows me to manage the condition "First" or "Second" correctly.

    I then modified the items in my enum so there is now a 'third party '. My problem is that structure business conditions still show as 'First' and 'second '; That is to say, I can't handle the "Third" condition My question is how to synchronize my case structure to show the updated enum values?

    VI, attached, the sample created with LabVIEW 2009 version 9.0f3 (32-bit) running on Windows 7.

    Thank you all for your help in advance.

    Michael O'Shea

    First tip: remove the value 'default' first case

    If you have done your VI pauses when you change your enum, which is a good thing.

    Now to synchronize, do a right-click on the border of the structure of the case and select 'add the case for all values', this is the option you are looking for.

    Tone

Maybe you are looking for

  • Add new tab/PIN to the start page. Impossible for the life of me to restore a deleted site/PIN...

    I accidentally deleted a pinned site my page tab (start). (You can remove by clicking on the icon in the upper left corner of the thumbnail, or remove by clicking the icon at the top right of the thumbnail). My question is, how do I ADD (or more prec

  • Why Melodyne appear not in my Garage Band Plug In?

    Hello I am using the 30 day trial of Melodyne to my vocal tracks in Garage Band. But I can not even see in my ins plug in option! Help! I'm going crazy trying to find how to open it in Garage Band! I followed the 1 million pages different tips of whe

  • HP Touchsmart 320-1030 RAM

    Hi, I'd like to update my RAM but I can't find modules that are 200 pins for the computer. I find the SO-DIMM modules with all the specifications corresponding except with a different amount of pine trees. I want to clarify the number of pins and if

  • How to place itself in a bunch of references to a sub - VI?

    In a Subvi, I use references to retrieve the current values of the control and change the properties of these controls in accordance with these values. I'm passing only three references in, but even if I table together to reduce the size of entry, th

  • While the loop helps... I think so

    All, I have a fairly simple VI who catches the units of measure (send an 'A') of a MARK-10 test bench and MARK-10 dynamometer. I am struggling with how, and where, I should place my While loop. I want VI to do this is if the units of measure are not