How to calibrate Quadrature Encoder signal

I have PCI-6601 and CB68-LP connector. How can I use these to interpret quadrature signals coming off an optical encoder (to sense the angular position of an-observatory dome). The encoder is 16-bit(don't know what this means in terms of PPR). I want to have a display in Labview that will show me the position of the dome in a fraction of 360 degrees with some reference(true north?), the dome rotation controlled by a three way switch(clockwise-off-anti-clockwise). I don't have much experience with labview and any help will be appreciated.

If the encoder is 16 bit then it would seem that: -
360/65536 = 0.0054931640625° or there abouts.
You can break the project down into two halves nicely.
1) Hardware interfacing.
2) Software read out.
The hardware interfacing means two basic things:
1.1 What is the encoding technique
1.2 How are the signals conditioned for output to an external device.
The software is classic:
2.1 Input
2.2 Process
2.3 Output
The optical encoder could be one of a few types and you need to understand both the signalling / interface and the coding technique to progress further. A good start will be the manufacturers data sheet for the product. Contact the manufacturer.
Once you understand the coding technique you will then know if the unit is absolute or relati
ve. This will then allow you to determine how you can point to true north (easily with an absolute encoder, it always tells you exactly where it is).
If it is a classic quadrature encoder then the relative phase of the reference and movement signals gives you direction. Counting transitions gives you realtive movement. But if the power went off on the PC. you don't know where you are unless you go to a home position! That could be 359° round !!!
Good Luck

Similar Messages

How to route Quadrature Encoder signal to CC1 using PCIe 1429 + IO extension card

Hi there,
i am currently trying to interface the Basler L304kc to the NI PCIe 1429 + Cameralink IO extension board
I want to operate the camera in Ex-SYNC level controlled mode. I would like to route external Quadrature Encoder signals (connected to the IO extension board) to the CC1 cameralink control of the camera
Currently, I cannot find this option either in MAX or the Camera File Generator.The L304kc camera file only provides pre-defined pulses, or MAX only offers "External","ISO","RSTI" options for the CC1 sources.
Is it possible to route the encoder signal from the IO extension board directly to the CC1 of the camera? Or is there a work-around?
Thanks!
Derek Chan
Application Engineer
Basler Asia Pte Ltd

Hi Alex,
I posted the following (similar) text to the support center but I think it is of common interest:
A) CL-card with ext. board. One can use the ISO, ext. and RS422 encoder inputs and also output cannels ISO and external.
There is also a SMB connector corresponding to the ext. channel 0.
B) with MAX one can define what kind of signals should be routed to CC1 to CC4. As I learned from
this side one cannot use MAX or the Camera File generator but has to do this manually in order to use RS422 encoder triggering!!!
C) on the other side there exists function to route and control signals explicitely, for example
* imgSessionLineTrigSource2 -> what is this good for then? All your manuals are saying that this is done in MAX or the camera file by defining what signal drives the correspondung CC ine?? On the other side there is an example in CVI that does not work ("Trigger Each Line From Encoder") (at least it does not work with the PCIe1430).
D) Can one implement the CC routing from MAX or the camera file manually with the following functions
* imgSessionLineTrigSource2
* imgPulseCreate2
* imgSessionTriggerDrive2
or does MAX use hidden functions ore mechanism to control the CL Cards?
E) I can use one single line to setup scaled encoder triggering
* imgSessionLineTrigSource2(iLS_ZK1_SessionID, IMG_SIGNAL_SCALED_ENCODER, 0, IMG_TRIG_POLAR_ACTIVEH, 0);
but this only starts to work if I reset the encoder position to zero by sending this to the CL card, i.e.
* imgEncoderResetPosition(SessionID);
AND only in positive counting direction!
If I just run though the zero position without a position reset I do not get ExSync on CC1????
Is the information where to route the Scaled encoder to coming from the camera file? Why cannot I simply and explicitely route the scaled encoder
signal to a certain CC line? Why using all those different approaches?
F) now if in addition to E) i use
* imgSessionTriggerDrive2(iLS_ZK1_SessionID, IMG_SIGNAL_EXTERNAL, 0, IMG_TRIG_POLAR_ACTIVEH, IMG_TRIG_DRIVE_SCALED_ENCODER);
to drive ext. 0 (SMB connector) I can see exactly this behavior on the scope. No signal until I reset the encoder counter. Then I get signals as long as the image sequence is running. After the recording the signal disappears.
kind regards, Holger h.baur(at)ivisso.com

Measuring distance using quadrature encoder

I am currently doing a project that requires the positioning and characterization of TV signals. As such, the position of the TV receiver is one important variable that i have to measure. I am required to automate the measurements and data logging using a PC/notebook. I have purchased a 2-channel HEDS-9000 quadrature encoder with 2000 CPR & the HEDS6120 codewheel - both from Avago Tech, to be interfaced with the notebook/PC. My idea is to get a TTL-to-RS232-to-USB converter to interface with the PC, so that i can feed the output from the encoder to the PC. However, i dun have much idea on how I can use LabView to interface the encoder and the PC. Can anyone offer some valuable advice?
Btw, the encoder module consists of 5 pins - Vcc, GND, CH.A, CH.B, with one pin not used.
Thanks !!

Hi,
I think one of the best and reliable options that should meet your needs is a bus-powered USB-M-Series device like the USB-6210.
The USB-6210 is a multifunction data acquisition device with 16 analog inputs, 4 digital inputs, 4 digital outputs and 2 counters. Each of the counters can interface directly to the quadrature encoder signals of your HEDS-9000.
It's very easy to use this device with the NI-DAQmx API for position measurements in LabVIEW. In fact there are some shipping examples that you can use for getting started.
I hope this helps,
Jochen Klier
National Instruments Germany
Message Edited by Jochen on 02-09-2007 09:18 AM

Does Stop task reset a quadrature encoder counter?

I am using an M-Series PCI-6280 board, with one of its onboard counters wired as a quadrature encoder.
1)I start the counter task, take a set of measurements with the counter, and then stop the task.
2) The encoder which the encoder counter is monitoring continues to output quadrature encoder signals into the PCI board's counter.
3) I start the task again, and perform another set of measurements.
Which of the following occurs?
Upon starting the task again, the counter's previous value was wiped and the measurements taken in (3) start at 0 counts.
The counter keeps the value it had before it was stopped and subsequently started, and the measurements in (3) cumulate on top of the measurements taken in (1).
The counter keeps the value it had before it was stopped, continues to increment/decrement position in (2) even after the task is stopped, and when the task is started in (3) the counter value is cumulative with the quadrature encoder pulses in (1) and (2).
Thanks in advance for the help.
Solved!
Go to Solution.

Hello acmap,
In this case The behavior will be the following:
Upon starting the task again, the counter's previous value was wiped and the measurements taken in (3) start at 0 counts.
However, you can specify the initial count value of the counter on the Initial Count terminal of the DAQmx Start Task VI, so it doesn't have to start at zero, and you can implement the behavior described in your second option.
Daniel

Do I need extra logic circuit for quadrature encoder using M-series DAQ PCI-6221?

Hi,
I understand that extra logic circuit, say quadrature clock converter LS7083/7084, is needed to enchance the reliability or integrity of the data for E-series board DAQ in accordance to application note: AN084.
This is due to the vibration/jitter of the motor during running.
Currently, I'm using M-series PCI-6221.
Is it this new model itself can eliminate to construct this extra circuit?
Coz I observed error is accumulating after motor rotating certain period of time. It defintely affect the control performance.
Other than using hardware, can we use software to eliminate/mitigate the error?
Please enlighten me. Thanks.
Best regards,
IANES

Hello,
The ap note you are referring to discusses circuitry that conditions the quadrature encoder signals before they get to the DAQ device to eliminate 'false' signals being sent to the DAQ device. The same system would apply to an M Series Device. I am not aware of any way to achieve this functionality in software. FYI, there is some good documentation for counters and counter applications for M Series. Take a look at the attached M Series help file. Hope this helps some.
-Alan A.
Attachments:
M_Series_Help.zip ‏1145 KB

How can analog signals are measured every several counters from Quadrature Encoder using USB-6221

how can I sample analog signals every counters from quadrature encoder using usb-6621?

There is a well documented example of what you are trying to do at :
http://zone.ni.com/devzone/explprog.nsf/webmain/DD85F07A7CA99F8F862568690062DE54?opendocument
Don't be afraid because of the BNC-2120. It is just used in this example to simulate the pulses from a device. So it is not needed in your case. Obviously, you will need to change the number of increments/rev according to your encoder to get correct RPM values.

How do I use a quadrature encoder as an external clock (PCI 6229)

Hello, ( a similar post has been placed on DAQ forum apologies as I did not know best place)
I have a PCI 6229 M Series data acquisition card. I want to use a quadrature encoder to be the external clock driving the acquisition of a number of signals. I have set up reading 24 signals each time a clock pulse is received using the DAQ assistant and set my external clock to pin pfi8 (I think) this is then connected to an encoder output. This works well enough until the encoder is run too fast when it appears I am either missing pulses or getting bounce.
How can I set up to clock using a quadrature encoder? I have seen a number of questions on this forum regarding quadrature encoders and reverse counting but not on using them as an external clock.
Basically I want to have the stability and "bounceless" nature of using two outputs from a quadrature encoder whilst still using an external clock. Is this just a case of configuring controls to certain pfi's? If so how is it done?
Any help or pointers would be helpful. So far I have managed very nicely by simply using the DAQ assistant and the interface it has would suggest that if configured for a certain pfi pin I could actually still use it.
Thanks in advance.
Kevin

Hi,
Well I've had alook into this for you and I'm not quite sure I understand what you are looking for.
Is it possible for you to phone back in to support?
The reason you are seeing bounce at high speeds, or indeed loss of points, is due to the sampling rate that you have set up.
What you will find is that the trigger will start an aquisition of a number of points at a certain rate. If your sampling rate is too low then you will not finish that sample batch before the next set of samples is recorded.
It is possible to use an external clock into a trigger or digital line, however this will limit the number of samples you can take to the speed of your encoder.
If you increase your sampling rates, and then configure a start trigger from a single input from the encoder you will be able to record a number of samples after a rising/falling edge. (Set the clock as an internal clock)
Hope this helps
AdamB
Applications Engineering Team Leader | National Instruments | UK & Ireland

Can I use the 'Export Signal Property Node' on a quadrature encoder?

Hi,
So I don't know which counter board I'd be using yet for this (it's used in conjunction with a PCI-6280--the PCI-6280's counter inputs are all taken and so I need another board), but assuming this is possible at all in DAQmx I wouldn't mind knowing whether, say, the PCI-6601 (or any other timer board for that matter) could do this. I'm programming this in LabVIEW 2010 by the way.
I want to have a counter which counts the number of pulses on one channel (I'll call this the 'clock' channel) between when another channel goes from low to high (which I'll call the trigger). It's basically a pulse width measurement, but I only care if there are more than n clock pulses between triggers. I need to have a hardware-timed digital signal which goes from low to high if there are ever more than n pulses between trigger changing state from low to high.
What I am planning to do is this:
Wire 'trigger' to the z-input of the quadrature encoder, and set the z-input value to some arbitrary large value such that, at the quadrature encoder counter task's settings, the counter reaches terminal count in n pulses.
Configure the quadrature encoder counter using DAQmx Export Signal Property Node (tutorial I was looking at is here: http://zone.ni.com/devzone/cda/tut/p/id/5387 ) to toggle a digital channel ('counter event output') from low to high if the counter reaches terminal count (ie, if the encoder reads n pulses).
If the encoder ever reads n pulses on 'clock' between two rising pulses on 'trigger', it sets counter event output high.
Is this possible? Reading through the manual of M series PCI-62xx devices, the index pulse loads the counter with a particular value so it seems like you could conceivably set the counter to the terminal count if you wanted. My only real problem is whether DAQmx Export Signal Property Node works on all counter tasks or just on edge counting tasks.
Thanks in advance for your help. If this isn't possible, I can reply with more details on the problem this is supposed to solve so that you can help me figure out an alternate method.
Solved!
Go to Solution.

There is probably a way to do it, but it it may be easier to use an X-series board for the job. They support a new counter capability for count reset on a digital edge without needing to be configured in encoder position mode. I am not sure exactly how that feature's been implemented however, so maybe it won't make things easier after all.
The plan based on the hoped-for behavior:
1. Configure an X-series counter for pulse generation based on "ticks" of your clock channel.
2. Set both initial delay and low time to the critical # of ticks.
3. Configure for count reset on a digital edge (if possible in pulse generation mode)
4. Configure the count reset value to be the critical # (or possibly 1 less, if possible in pulse generation mode)
5. If you want the output to remain high indefinitely, configure the counter task to use its own output as a
pause trigger, and pause while high.
The way pulse generation works is to preload a # of "low time" ticks into the count register. Then every source edge will decrement the count. When the count reaches terminal count (0), the counter's output is toggled (or can be configured to pulse). The register is then loaded with the # of "high time" ticks and the process continues.
You would be perpetually interrupting the count-down process as long as you got your triggers in time. The count would keep getting reset to the # of low counts, keep decrementing toward 0 without reaching it, and so on. If ever you did reach 0, the output state would toggle high, then the high state would prevent subsequent clock signals from decrementing the count.
You can conceivably do a similar thing with a 6601, but I'm pretty sure you'd need 2 counters working together to get it working.
-Kevin P

Recording quadrature encoder and AI signals simultaneously and generating output TTL signals in one VI

I want to record simultaneously encoder, pressure and other AI signals and output a TTL signal for every other pressure signal. I have two VIs: One is to record all signals and the other is to generate TTL signals.
1. Since I'm new to Labview, I would like to double check with experts that if my VI (attachment 1) did what I expect. I would like to have DAQ box read and write encoder signals and pressure signals at the same time so I can plot PV diagram.
2. During acquisition, some data points are usually missed, shown in attachment 2. Is there any way to solve it?
3. I tried to combine two VIs but it never work (attachment 3). Can anyone give me any suggestions?
PS. Labview 9.0 and NI USB-6216 are used.
Dummy signals are 30Hz sine waves for pressure and 2 TTL signals for encoder A and B at 5kHz.
Thank you!

Thank you for your help, Peter!
I attached the wrong file for attachment 1. The initial code for measurement is attached here.
The sampling rate is 20000 and the sample mode is continuous.
For missing data points, it improved when I add "wait until next ms multiple" in while loop.
Follow the example you gave me, I'm able to generate TTL signals in one vi, attachment 2. Could you please check if it's correct?
It looked fine with simulated signals and hope it will go well with real engine tests.
I have two more questions:
1. Does the input number for wait until next ms multiple should always be the same as "samples per channel" in sample clock?
2. How will the value of "samples per channel" in sample clock affect data acquisition? I tried 1000 and 10 but didn't see any difference between these two.
Thanks a lot.
Attachments:
recording VI.png ‏332 KB
AI+CI+CO.png ‏72 KB

NI 6602 measure quadrature encoder with two signal edge sepearation

Is it possible to improve the position measurement for X4 encoders,
that the measurement starts at start trigger and stops at the stop
trigger signal like the normal two signal edge seperation measurments.
Everything I tried don't works. Does anyone have an idea. Thank You
for Your trouble.

Hello Yong,
You have no wait time within your for loop. This means that the loop will execute as fast as possible, but not at a constant rate. To acheive a more constane rate, try inserting a Wait Time of 1 ms. This will get you a loop with a 1 kHz rate.
How fast is your PWM Signal? It may be that you are missing some two edge measurements while waiting for the loop to iterate.
I suggest merging your error clusters out of the DAQmx Read.vis. Right now, you are just clearing out any errors. Let me know if you start returning any errors once you have done this.
Regards,
Sean C.

Speeding up quadrature encoder read out

Hi,
I`m using a quadrature encoder together with a 6259 DAQ Card and BNC2110 Terminal Block.
I managed to have it working with the DAQ-Assistent at 80Mhz using the Counters and reading one value at a time. Before the DAQ-Assistent I used a DAQmx command to connect PFI10 and PFI9 as the BNC2110 Terminal only outputs PFI0-9. This works but it is really slow, the distance between each measurement point is around 6 us. The VI is in the attachement (AquadB_one_value.vi)
So I thought I might use the n-values version with the DAQ-Assistent but this does not work and I dont see any reason why, it is complaining about that connection between PFI10 and PFI9 which it didnt do before in the one-value-version. The VI is also in the attachement (AquadB_n_values.vi)
I also tried another method using a VI I was given some time ago and modified it but here the distance between each measurement point is also around 6us. This VI is also in the attachement (Counter - Read Encoder.vi)
Or am I missunderstanding something? The minimum achievable time distance between measurement points should be 1/80.000.000 s where of course the value can only differ 1/0/-1 because it has only calculated one new change in the A and B Signals right? I thought with using the n-values it is storing all the calculated values in the memory and I am transferring them afterwards for doing all the "post-processing"?
If I am wrong, how can I spped up the read-out of the calculated values any other way?
Best regards
Attachments:
AquadB_n_values.vi ‏56 KB
AquadB_one_value.vi ‏49 KB
Counter - Read Encoder.vi ‏98 KB

Hi Dani_munich,
I just realized that you asked the same question in our Service request. In the service request, I was missing out more information which I found them here by chance . I will further assist you in the SRQ you have created. I also sent you an email.
Regard
Anoj
Anoj Mubarak
National Instruments

Programming quadrature encoder

I'm trying to program a incremental optical encoder with nidaqmx 7.4, with C#, using the PCI-6071e card. I want to measure position, velocity, and acceleration.
As per the "How Do I Use a Quadrature Encoder with My Data Acquisition Board?" document, channel A of the encoder is connected to ctr0_source, channel B is connected to DIO6, and index is connected to ctr1_source.
I'm trying to run the the MeasAngularPositionBuffered_Cont_ExtClk example. However, an exception is thrown when calling myTask.CIChannels.CreateAngularEncoderChannel.
The messagebox says "Selected physical channel does not support the measurement type required by the virtual channel you are creating. Create a channel of measurement type that is supported by the physical channel, or select a physical channel that supports the measurement type"
Also, there is an option in the example program to enable the Z index. How does that program know which channel to read the index pulse?
I'm new at data acqusition, so any other hints regarding optical encoders are appreciated.
Thanks,
Gerry

You also may be able to measure position using the "Count Edges" measurement with an external direction control. This may be enough for your purposes. Just bear in mind that quadrature encoders typically give off noisy signals, so you might have to build an external circuit to clean up the input signals. Let me know if you need more information on doing this with your E Series device.
gus....

Troulbe in measurement quadrature encoder with 6601

Hi,
Thanks for Ross's help.But I cannot differ 6601's x4 mode from other counter/timer counting mode. In measurement position, what difference between them. And I just want to know whether my application viable.
We are trying to measure position with 6601. The frequency of quadrature encoder is from 100Hz to 8MHz. Now, we connet the A,B and Z channel directly to counter . Using the example in CVI, we change the filter to 100ns and use x4 mode. It works perfect at low frequency.
The problem is when the frequency of encoder is higher than 2MHz, the accuracy decreases greatly. I'd like to know about following:
1.Can 6601 do the previous task enough? Or I must change to use 6602.
2.If
6601 is available, is there any way to increase measurement accuracy ?(in software or wire connection )

>jimmyjimmy2000
"Hi,
Thanks for Ross's help.But I cannot differ 6601's x4 mode from other counter/timer counting mode. In measurement position, what difference between them. And I just want to know whether my application viable.
>>mross>The application is viable. However, the use may be difficult.
>jimmyjimmy2000
We are trying to measure position with 6601. The frequency of quadrature encoder is from 100Hz to 8MHz. Now, we connet the A,B and Z channel directly to counter . Using the example in CVI, we change the filter to 100ns and use x4 mode. It works perfect at low frequency.
The problem is when the frequency of encoder is higher than 2MHz, the accuracy decreases greatly. I'd like to know about following:
1.Can 6601 do the previous task enough? Or I must change to use 6602.
>>mross>The 6601 is just as good as the 6602 at 2MHz. Therefore, a 6602 will have the same problem of inaccuracy.
>jimmyjimmy2000
2.If 6601 is available, is there any way to increase measurement accuracy ?(in software or wire connection )"
>>mross>Yes, in the wire connection you can make improvements.
6601 can count as fast as 20MHz (60MHz with prescaling). The signal is noisy (containing addtional, incorrect information).
You must use an oscillosope to look at the signal. Look at it when 6601 is counting correctly, and look at it when 6601 is "malfunctioning".
The counter will increment whenever the signal is high for more than 5 nanoseconds. The conditions for "High" and "Low" signals must be strictly met. If the signal is greater than 0.8V, the counter may increment. The signal must then drop below 2 Volts for a "Low" to be seen.
This sounds wrong, but is true. The counter is expecting TTL signal conditions (Transistor -Transistor Logic). This specification is very broad.
A "High" will absolutely be recognised if the signal is greater than 2.0V.
A "Low" will absolutely be recognised if the signal is less than 0.8 V.
However, the range from 0.8V to 2.0V is "undefined." This means the counter could increment at 0.8V. It has been my experience that National Instruments TTL will always see 0.8V as a "High." If your noise exceeds 0.8V you will never be able to count accurately.
The problem will be solved when your encoder signal is read cleanly by the 6601. This is why I gave you the URL for US Digital in the previous answer. The circuits they sell can help to clean up the counter signals. You will have to see what works best, since I don't exactly understnad you application. If the noise is very bad, you may wish to use the Encoder to Binary Number circuit. There will be no noise in the reading of a binary number. Since your encoder may run as fast as 8MHz, you must be sure the circuit you choose is also this fast.
The other solution is to eliminate the noise which is causing the counter to trigger falsely. THis can be a very interesting problem to solve. Please look a this NI link:
Field Wiring and Noise Considerations for Analog Signalsv
http://zone.ni.com/devzone/conceptd.nsf/webmain/01F147E156A1BE15862568650057DF15?opendocument
Follow these instructions very carefully.
Also, this book is helpful to explain noise and how one may reduce it.
From Amazon.com you can get Grounding and Shielding Techniques, by Ralph Morrison.
http://www.amazon.com/exec/obidos/ASIN/ 0471245186/104-3492923-2811911
Be very careful how you wire the circuits. Try to use only one ground point.
The worst source of noise can be the motor and drive that spins the encoder. Be particularly careful in wiring this apparatus. A simple solution can be to use an air powered motor insted of an electric motor.
Good luck,
Mike Ross

RPM Measurement using Quadrature Encoder and PXI 6602 counter

Hi,
I am on a project at work where I need to verify the speed (in RPM) of an unloaded motor which can operate up to 1400 rpm. After doing some research, i determined that a quadrature encoder could be used to make the measurement. I am looking at this encoder http://sine.ni.com/nips/cds/view/p/lang/en/nid/205321.
I have a PXI 6602 counter/timer module in which I would like to interface to the quadrature encoder. I would like to create a VI that allows me to calculate the speed using the encoder. Can someone provide me with details of what needs to be in the VI or an example which can do this? At the most basic level, i want to calculate the speed on demand. After doing this, i would like to figure out how to quickly calculate the speed so that i can determine response time of the speed changing within sub-millisecond resolution (1 ms resolution max).
Further, i created a VI that allows me to change the pulse width of a 100 Hz pulse train at run-time which tells the motor controller the desired speed. I would like to be able to use this VI to change the speed of the motor and the first VI (that I am seeking help about) to calculate the response time (time between the initial speed and settling at the new setpoint).
I am familiar with the NI example finder, but have not been able to find an example that I can use.
Thanks,
Gary

Hey Gary,
I think for you setup, you should try using the Meas Dig Frequency - Low Freq 1 ctr. You can find it by searching example finder with 'low freq'. This vi tells you the frequency of a digital signal by sampling between two pulses and inverting the time between pulses. If you hook up your encoder to a counter and have that counter specified in the vi, it will be able to give you on demand readings of frequency (you can do some multiplication to get the rpm value, freq*60/pulses per revolution of encoder). A simple way to take continuous readings is to put a while loop around the daqmx read and the data output of the read. You can also replace the numeric indicator to a waveform chart to graphically display the change of frequency or rpm readings over time.
You should be able to integrate this as two separate tasks with the pulse train vi you created earlier.
Hope this helps
Luke W

Read RPM from Quadrature Encoder

Hi Everyone,
I wish to measure the RPM of a shaft using a quadrature encoder and a PCI-6259 card. I've seen a few examples on reading position, which i have managed to get working, but Im not sure on how to get RPM. Any tips or code examples would be greatly appreciated.
Thanks,
David

Hi All-
Thanks for the suggestion DJ, but your VI will not work as it is written using the Traditional (Legacy) NI-DAQ driver and David's M Series card is only compatible with the NI-DAQmx driver.
To answer David's question, it is not possible to directly measure position and count edges at the same time. What you can do is count edges with external Up/Down control (basically the same as a X1 encoder) and then use the edge counting to calculate both frequency and displacement in ticks/degrees/RPM/etc. I have attached an example I did recently that shows how to use an edge count with external Up/Down control (i.e. PFI10 or PFI11 for M Series ctr0 or ctr1, respectively) provided by the 'B' phase signal and the 'A' phase provided to the counter source.
Hopefully this helps-
Tom W
National Instruments
Attachments:
32bit_Cnt_Edges_to_Quad.vi ‏73 KB

How to calibrate Quadrature Encoder signal

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