Measuring times of digital events on a NI PCIe 6259

I am trying to figure out how to acquire time stamps every time a digital input (Boolean) changes values relative to the beginning of a AO output. Ideally, I would like to reset the time stamp to 0 each time the AO output occurs (different trials). Both counters on the 6259 are free, however I am already using the ao/SampleClock in my VI. Thank you for any help.

Hello Joes,
Since you have 0-30 events which you want to measure the time of, it would be easiest to calculate the time in post processing. You can use a start trigger to trigger both the analog output and the digital input. Using the start trigger will synchronize the start time. The high to low transitions can be found in the recorded data and the time can be calculated using the position in the data array and the delta time between samples.
Eric
Eric Liauw
AE Specialist - Automated Test | CLD | CTD
National Instruments

Similar Messages

Writing to digital port disrupting counter on PCI-6259? (nidaqmxbase)

Hello,
I've set up my PCI-6259 with an angular encoder counter, as per the C code example at http://zone.ni.com/devzone/cda/epd/p/id/5735
This appears to work great, but I would also like to use my PCI-6259's digital lines to control a TTL switch on the encoder it's measuring (among other things). If I set up a separate task in the same program and install a new DOChan to the task, it works great: I can control the TTL and measure the encoder position at the same time.
However, I would like to be able to control the digital lines, e.g., via a script, while leaving the encoder readout running continuously. I tried running the angular encoder counter example code, and while it was running, I ran the dio/writeDigPort example.
First of all, the writeDigPort took about 3 times longer than usual to run. It wrote to the digital line successfully, but as soon as it had, it corrupted the counter somehow. The angular encoder example began to spit out garbage, rather than the measured angle.
Is this just a limitation of nidaqmxbase, wherein I cannot use the PCI-6259 resource from multiple processes? I can imagine this being the case, since I think the counter setup is using a DMA.
Or is there a workaround? Any advice is much appreciated, thanks!
-Chase

I think what was meant is that DAQmx Base is not multi-thread safe. From the readme:
NI-DAQmx Base is not multi-thread safe. In LabVIEW, use the error cluster to
force execution order. In C, use only one thread to make API calls; especially
for task/channel creation and deletion.
So, if using DAQmx Base, all of your functions should be in the same thread (i.e. don't make parallel calls to the driver).
Having said this, I notice you're using the PCI-6259 which is supported in DAQmx for Linux. You didn't mention what OS you're using, but if you are able to use the full version of DAQmx I would recommend doing this. DAQmx is multi-thread safe, and provides more functionality and better performance than DAQmx Base.
Best Regards,
John Passiak

Measuring time between activation of two boolean

Hello
I want to measure the time elapsed between activation of two boolean variables/indicators. In my code I have DAQ acquiring 2 digital signals which trigger corresponding 2 boolean indicators. Now I am trying to measure time between the event when my first boolean indicator gets the signal and the event when my second boolean gets the signal. I am attaching my code. I checked DAQ and my indicators everything works fine, but just when I try running the code with the 'elapsed time' part, its not running. Any help will be appreciated.
Thank You.
Attachments:
Test Code.vi ‏45 KB

So, feel free to give more detail. I'll just give you a couple thoughts:
1) The primary issue with your code is that it probably doesn't do what you think it does. How this VI will run is that it will get one data from the DAQmx routine, then pretty much stay in the inner while loop since the event structure has an indefinite timeout. Worse, I don't think changing the value of the boolean controls would trigger the value changed event anyways. In the end, you don't even need the Event Structure to do what you want to do, nor do you need the inner while loop. Just check the values for each iteration of the outer while loop instead and do what you need to do with those.
2) You are acquiring only one data point at a time. Which is OK if your events are particularly slow with respect to the effective sampling rate of the of loop (which might be able to pick up signals that change on the order of milliseconds or perhaps a bit less). If your signals are faster, you need to think about reading lots of samples at a time (arrays of booleans) and properly triggering your acquisition close to the event it needs to pick.
3) If your signal is a pulse, make sure that the pulse width of the signal is much longer than than 1 / sampling rate. If it isn't, you could miss the pulse entirely doing this approach.
4) The faster signals (as long as your have a quick enough sampling rate), the best thing is always to use a counters approach. In many of the DAQ cards and peripherals that NI offers, there are counters that can be driven with the sample clock (one of the fastest clocks on the device) or even a faster time base, and then the 'events' can be used to trigger acquisitions of the counters. Meaning you get exactly what you want: data points that correspond to times when events occur.

Best way to measure time?

I have labview 7.0 and SC-2345 with several digital inputs. I have to measure time between digital input(rise or fall)and stop signal comes in my program with compare etc.
I have tried to measure time with 4 sequences and "get date/time in seconds" and i have also tried to use loop with shift register.
It seems not to work or accuracy is not enough. so how to do that?

I am very sorry If you feel I came across unfriendly in any way, my intentions were sincere and I wanted to help you improve your code by pointing out some common mistakes. Believe me, some of my early labVIEW diagrams from 10 years ago are much worse. In the meantime I have accumulated some experience with daily use, but am still learning every day.
By the way, I an not affiliated with National instruments. This is mostly a peer help forum where LabVIEW users from all over the world help each other improve their coding skills. (Only users with blue names are employed by NI!)
Certain things are not obvious looking at your code and once the desired functionality is clear we can help you to a more optimized version that actually works. Whatever you are feeding to the "elapsed time" indicator has nothing to do with elapsed time, but counts the iterations of the middle while loop. It is either 1 or 2, depending on the inputs. There has to be a more interesting output (see my next post!).
For example, let's just look at your inner while loop (see attached image). (1) The number of iterations is known when the loop starts, thus a FOR loop is more appropriate. (2) You are comparing a DBL with an integer using "equal". If by chance the operator would enter a fractional time (e.g. 1000.5), the comparison would never become true and this loop would go on forever. Your program will never finish! Not good!
An alternative, but safe code is shown below in the image. For integer times, it has exactly the same functionality.
Apparently, you want to measure elapsed time, and I am guessing elapsed time used by the code in your middle loop. I will attach a simplified example based on your program in the next message here.
LabVIEW Champion . Do more with less code and in less time .

How can I measure time between transitions at digital input

I am using LabVIEW 6.0 to measure the time duration between 2 transitions in a digital input port. I have a set up including an HP 34970A Data Acquisition unit with the 34907A Multifunction Module plug-in. The LabVIEW program is trying to poll the digital input for level changes and then using the Time function(Tick Count) to check the times at the transitions. However this method doesn't work reliably as I have to measure time periods of 500ms.
Is there any good way of mesuring time period with the above setup. I don't have a module which connects to the internal multimeter in the 34970A. The other stuff I have are a HP 34903A(Actuator Module) and a HP 33120A(Function/Waveform Generator).
Any method for m
ore accurate time measurement with the above setup will be appreciated. If not, what else do I need to make accurate time measurements.

Frankly I doubt that you're going to be able to measure time interval with much accuracy. You're periidically polling a static digital input and how often you poll is going to vary. You could try polling as fast as possible and eliminate as many background tasks as you can. If your tolerance for the measurement is plus or minus 100 msce, then maybe you'll get a decent measurement most of the time. If it's plus or minus 5/10 msec, then it will never happen. The pc's clock is just not that accurate and a software timed loop on Windows is not deterministic enough. Get a counter/timer board for something really accurate or use a scope to capture the waveform.

How to measure RPM using digital I/O

Please tell me how to measure RPM using Digital Input or please give me a code for this.

You probably aren't going to find anyone to just give you code. Especially because you don't specify the hardware you're using. Doing this on FPGA is different than using DAQmx to do it. With FPGA you count pulses over a specified time. Using boolean logic from the digital DI node is a common way but there are others. (if you are using FPGA I can draw up an example, but I believe there is one on NIs website if you search google for it),. Then, if you want, you can run the data through an IIR filter, especially if you have a low resolution or slow moving encoder. Either of these conditions can result in very large difference of RPM even if the actual speed is not varying much (if you need an example why I can provide more detail, but some simple math calculating RPM should explain this. Obviously lower resolution will giv eyou less accurate results).
If you use DAQmx you can set up a frequency task and it will return the number of pulses in a specified time frame; then you can convert this to RPM based on your encoder resolution and take the same steps of running it through a filter to smooth it out if need be.
CLA, LabVIEW Versions 2010-2013

How can I create RT time-triggered events?

We have a RT VI running on a PXI. One of the RT event loops handles turning on and off digital outputs at precise times. Because we want high precision, the loop is running at a high rate (1 KHz) and every iteration, we check to see if it's time to do something. But this seems inefficient to me because the vast majority of the time, we're sitting and spinning. Is there a way to turn this from a polled system to an even-driven system? I'd like to schedule events to occur at given times and use an event handler to process them. But how do I schedule a time-triggered user event?
Thanks,
Keith.

There are other RT timed loops running, but I'm not sure if it counts as "a lot of stuff." As for what controller, I'm not sure (I inherited the system) but MAX says it's a PXI-8187 with a SCXI-1102 and a PXI-1052 (SCXI) SCI with a few cards in it. Is that what you're asking?
How do I find out how much CPU is being used?
The time trigger is like this: The operator hits a "go" button on the host VI. This signals a sequence of on/off timed events that are relative to the time when the button was pressed. The relative timing sequence is fixed before the VI is run and does not change afterwards. It's also a one-shot -- each digital output is turned on once and off once, just at different times.
If the way we're doing it is fine, I'm cool with that. I'm just trying to see if I can simplify things. The previous developer had mentioned doing a lot to optimize, so looking for inefficiencies is fresh in my mind, but I don't know (yet) for sure if there are current problems.
Thanks,
Keith.

How to measure time delayed measurement

Hi All:
I am using TDS3064 scope to measure time delay betwwen two channels (using IVI driver
complience package 2.2 for scope IVI driver). I look through drivers, but not able to find
delayed measurement function. Is there any alternate way to measure time delay betwwen two
channels. If possible please provide me example. I am new to LV programming.
Thanks
DBhagat

You have to understand something about IVI class drivers. To support portability, those functions that are common to a class are what you see in the driver. Some scopes might have the ability to measure time delay between trigger points on different waveforms but many don't. If there is such a function supported by your scope, then you can make a call to the instrument specific driver or a VISA Write/Read. Of course, you then loose the portability feature of IVI which, imho, is about the only reason to use IVI class drivers. What I would recomend is that you do a capture of both traces and then do an analysis of the raw data in LabVIEW. One way to do this is with Trigger Detection for 1 Channel (Analyze>Waveform Monitoring palette). Wire each channels data to the function and obtain the time for each trigger event. The function will return the time for each event that you can use to calculate the difference.

Measuring time in milliseconds

Hi,
I have to measure time in millisecond between two user events in Applet, so I did this:
Date startDate = new Date();
// Users answer some questions
Date endDate = new Date();
int timeElapsed = endDate.getTime() - startDate.getTime();It was all fine, until the users figured out to cheat this system: they changed their computer's clock before answering the final question.
So, is there any way to measure time in milliseconds and its independent from the computers clock?
Thanks!

meikop wrote:
Thanks!
I have a client - server application indeed.
So as I understand, there's no good solution on the client (applet) side only - there's no way I can measure exact time and not be worried about clients computer clock? Any theoretical explenation ?
Otherwise I have to mesure the time on the server side - I had it implemented some time ago:), but the clients started to complain about network latency etc so I decided to measure the time on the client side - not so good idea after all :)?
I'll probably have to calculate each clients average network latency and so on...
One can handle the client side clock being changed by the user by keeping a 'correction' in the client which is the difference between the client clock and the server clock. This way one only needs to update the correction at intervals - I use 1 minute update in my Bridge game. I don't need millisecond accuracy but it would not seem to be too difficult to correct for the network latency in calculating the correction.
P.S. You would do better to use System.currentTimeMillis() rather than construct a Date() object which actually uses currentTimeMillis() behind the scenes.

In setting up my ICal calendar I have specific times (as new events) that I want to be included in the print out. This doesn't happen.

In setting up my ICAL calendar I have specific times (as new events) for each day. When it prints out the time does not show up (rather its a bar). I would like the time for each appointment to print out. How do I do this?

These are two possible approaches that will normally work to move an existing library to a new computer.
Method 1
Backup the library with this User Tip.
Deauthorize the old computer if you no longer want to access protected content on it.
Restore the backup to your new computer using the same tool used to back it up.
Keep your backup up-to-date in future.
Method 2
Connect the two computers to the same network. Share your <User's Music> folder from the old computer and copy the entire iTunes library folder into the <User's Music> folder on the new one. Again, deauthorize the old computer if no longer required.
Both methods should give the new computer a working clone of the library that was on the old one. As far as iTunes is concerned this is still the "home" library for your devices so you shouldn't have any issues with iTunes wanting to erase and reload.
I'd recommend method 1 since it establishes an ongoing backup for your library.
Note if you have failed to move contacts and calendar items across you should create one dummy entry of each in your new profile and iTunes should merge the existing data from the device.
If your media folder has been split out from the main iTunes folder you may need to do some preparatory work to make it easier to move. See make a split library portable.
Should you be in the unfortunate position where you are no longer able to access your original library or a backup then then see Recover your iTunes library from your iPod or iOS device for advice on how to set up your devices with a new library with the maximum preservation of data.
tt2

Can I hide the set time in the event boxes in Week View?

Can I hide the set time in the event boxes in the Week View?

David
No way around this that I can find. That toolbar pops up if you pause the show.
The nearest I could figure is to use the settings button for a long slide - 'Play each slide for 120 seconds' then tapping the arrows will move the slides along without showing the toolbar. And the 120 second slide is almost as good as a pause.
iPhoto menu -> Provide iPhoto Feedback
Regards
TD

Error 1046: Type was not found or was not a compile-time constant: Component Event.

Hi Everyone..
I am getting an Error 1046: Type was not found or was not a compile-time constant: Component Event.
The ComponentEvent class has been imported,and also the event handling code is there. I am not sure what else is wrong, hope somebody can advise me. Thanks. The code is below, the point where the error occurs as indicated by the compiler has been highlighted.
package
import flash.display.Sprite;
import flash.media.Camera;
import flash.media.Microphone;
import flash.media.Video;
import fl.controls.TextArea;
import fl.controls.Button;
import fl.controls.TextInput;
import flash.events.SyncEvent;
import flash.events.MouseEvent;
import flash.events.FocusEvent;
import flash.net.SharedObject;
import flash.net.NetConnection;
import flash.net.NetStream;
import flash.events.NetStatusEvent;
import flash.events.FocusEvent;
import flash.events.ComponentEvent;
public class VideoChat extends Sprite
private var button:Button;
private var text_so:SharedObject;
private var textArea:TextArea;
private var textInput:TextInput;
private var chatName:TextInput;
private var nc:NetConnection;
private var nsOut:NetStream;
private var nsIn:NetStream;
private var rtmpNow:String;
private var msg:Boolean;
private var cam:Camera;
private var mic:Microphone;
private var vid:Video;
public function VideoChat ()
   //Set up UI
   textArea = new TextArea();
   textArea.setSize(500,280);
   textArea.move(20,54);
   addChild(textArea);
   textInput = new TextInput();
   textInput.setSize(500,24);
   textInput.move(20,340);
   textInput.addEventListener(ComponentEvent.ENTER,checkKey);
   addChild(textInput);
   button = new Button();
   button.width=50;
   button.label="Send";
   button.move(20,370);
   button.addEventListener(MouseEvent.CLICK, sendMsg);
   addChild(button);
   chatName = new TextInput;
   chatName.setSize (100,24);
   chatName.move (80,370);
   chatName.text="<Enter Name>";
   chatName.addEventListener (FocusEvent.FOCUS_IN, cleanName);
   addChild(chatName);
   //Connect
   rtmpNow="rtmp:/VideoChat ";
   nc=new NetConnection;
   nc.connect (rtmpNow);
   nc.addEventListener(NetStatusEvent.NET_STATUS,doSO);
   cam = Camera.getCamera();
   mic=Microphone.getMicrophone();
   //Camera Settings
   cam.setKeyFrameInterval(15);
   cam.setMode (240, 180, 15, false);
   cam.setMotionLevel(35,3000);
   cam.setQuality(40000 / 8,0);
   //Microphone Settings
   mic.gain = 85;
   mic.rate=11;
   mic.setSilenceLevel (25,1000);
   mic.setUseEchoSuppression (true);
   //Video Setup
   vid=new Video(cam.width, cam.height);
   addChild (vid);
   vid.x=10, vid.y=20;
   //Attach local video and camera
   vid.attachCamera(cam);
private function doSO(e:NetStatusEvent):void
   good=e.info.code == "NetConnection.Connect.Success";
   if(good)
    //Set up shared object
    text_so=SharedObject.getRemote("test", nc.uri, false);
    text_so.connect (nc);
    text_so.addEventListener(SyncEvent.SYNC, checkSO);
private function checkSO(e:SyncEvent):void
   for (var chung:uint; change<e.changeList.length; chng++)
    switch(e.chageList[chng].code)
     case "clear":
      break;
     case "success":
      break;
     case "change":
      textArea.appendText (text_so.data.msg + "\n");
      break;
private function cleanName(e:FocusEvent): void
   chatName.text="";
private function sendMsg(e:MouseEvent):void
   noName=(chatName.text=="<Enter Name>" || chatName.text=="");
   if (noName)
     textArea.appendText("You must enter your name \n");
   else
    text_so.setProperty("msg", chatName.text +": " + textInput.text);
    textArea.appendText (chatName.text +": "+textInput.text +"\n");
    textInput.text="";
private function checkKey (e:ComponentEvent):void
   noName=(chatName.text=="<Enter Name>" || chatName.text=="");
   if (noName)
     textArea.appendText("You must enter your name \n");
   else
    text_so.setProperty("msg", chatName.text +": " + textInput.text);
    textArea.appendText (chatName.text +": "+textInput.text +"\n");
    textInput.text="";
//Create NetStream instances
private function checkConnect (e:NetStatusEvent):void
   msg=e.info.code == "NetConnection.Connect.Success";
   if(msg)
    nsOut=new NetStream(nc);
    nsIn=new NetStream(nc);
    //NetStream
    nsOut.attachAudio(mic);
    nsOut.attachCamera(cam);
    nsOut.publish("camstream");
    nsIn.play("camstream");

Hi Guys...
I have found out what is wrong. I was importing the wrong package the correct one should have been:
import fl.events.ComponentEvent;
instead of
import flash.events.ComponentEvent;
I hope this is helpful for anyone caught in a simillar situation as me...Thanks..

How to Set A Default Start Time For New Events In Calendar?

How to Set A Default Start Time For New Events In Calendar?

John,
Thanks for that suggestion - could not get it to work. However, I did manage a different approach. I finally determined the sequence of events in terms of how the various events and listeners fire (I think).
Basically, the CalendarActivityListener fires, followed by the listener associated with the Calendar object's Create facet, followed finally by the CalendarEventListener - the final is where the TriggerEvent is available and then finally, control is passed to the popup/dialog in the Create facet. So, my approach of trying to set/get the TriggerDate in the user's HTTP session was doomed to failure because it was being get before it had been set :(
Anyway, I ended up adding a bit of code to the CalendarEvent listener - it grabs the current BindingContext, navigates through the DCBindingContainer to derive an Iterator for the ViewObject which drives the calendar and then grabs the currently active row. I then do a few tests to make sure we're working with a "new" row because I don't want to alter start & end dates associated with an existing calendar entry and then I define the Start and End dates to be the Trigger Date.
Works just fine. Snippet from the listener follows
BindingContext bindingContext = BindingContext.getCurrent();+
*if ( bindingContext != null ) {*+
DCBindingContainer dcBindings = (DCBindingContainer) bindingContext.getCurrentBindingsEntry();+
DCIteratorBinding iterator = dcBindings.findIteratorBinding("EventsView1Iterator");+
Row currentRow = iterator.getCurrentRow();+
if ( currentRow.getAttribute("StartDate") == null)+
currentRow.setAttribute("StartDate", calendarEvent.getTriggerDate());+
if (currentRow.getAttribute("EndDate")==null)+
currentRow.setAttribute("EndDate", calendarEvent.getTriggerDate());+
*}*

How do i get final cut pro x to recognize my time capsule in event library

how do i get final cut pro x to recognize my time capsule in event library?

Yeah I'm getting the same issue. I purchased a new Mac Mini yesterday purely to use the new FCPX, and now on day 1 I'm already running into problems... please don't make me switch to Premiere.
Set up the computer with external yesterday, never set anything to Time Machine. Here's a screenshot of the drive, formatted on Mac OS Extended (Journaled):
And here's a screenshot of FCPX not recognizing the drive:
Apple please respond to this post, would really appreciate some help here troubleshooting.

Setting time critical digital output based on axis position (PCI-7358)

HI,
I need to set a time critical digital output based on encoder position (this will switch fast acting valves). I was planning to try the general purpose DIO but I can't find any examples, I have been through the manuals, searched the site etc. Where can I find help with this, all the examples only seem to deal with digital input triggering or RTSI? I'm thinking of an onboard program that just monitors encoder positions and sets digital outputs.
Some time back I seem to remember reading that general purpose DIO should not be used for time critical operations, is that correct? And if so what are the other options - RTSI going to another DIO board? The DIO really needs to be deterministic, is RTSI the only option?
Any advice appreciated / Martin
Certified LabVIEW Architect

Even with an onboard program you will always get a delay of several milliseconds between your axis has crossed the position and until the digital outputs are set. If this is ok for you then you could choose this approach.
For the case that you only want to toggle one digital line the Breakpoint feature should be the best solution as it toggles the breakpoint output almost immediately when the breakpoint positions are reached.
If you need to change a whole pattern instead of only a single line then the approach you mentioned would be the best solution (RTSI and high-speed DIO like the 653x boards). Combine this approach with the breakpoint feature by routing the breakpoint output to RTSI and using this as a update clock signal for the DIO board.
Best regards,
Jochen Klier
National Instruments Germany

Measuring times of digital events on a NI PCIe 6259

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