Arm start trigger

I got two NI 6221 DAQ cards (M-series), each of which has two counters. I want to take the readings from three counters and sychronize them.
Here, I attached the vi that I am using. The problem is that how I can get the arm start trigger? It is stated that the arm start trigger would be better used to sychronize three signals. Could I use vi to generate start trigger sources? Comments are greatly appreciated! Could I use functino generator to simulate the trigger source? Thank you very much in advanced!
Attachments:
sz.vi ‏180 KB

Hi Mayasong,
In this example, the arm start trigger is setup to check for a rising or falling edge on a specified I/O line - labelled trigger source. This will synchronize the counters, and they will start counting when the start trigger condition is met.
What event exactly do you want to start the counter acquisition on? Something from within software, or a hardware event?
If you'd like to synchronize from with a VI, you could write code (eg a function generator) to generate this pulse on an output line, then loop that back into the input you select to arm the trigger. Alternatively, you can do this with a RTSI cable connected between the two cards inside your PC.
This link (below) may help you with synchronization:
http://zone.ni.com/devzone/conceptd.nsf/webmain/6DC991028566309886256F990080A720
Hope this helps!
Mark
Applications Engineer
National Instruments

Similar Messages

About arm start trigger

Hello all,
can anybody post an article explaining the "arm start trigger", its relationship with "start trigger", and how to use it under different scienarios, such as for different counter tasks, encoder and edge counting etc?
I just found it's hard to get enough example from labview shipped package.
thanks
feilong

Hi feilong,
What device are you using? If we know that it will be easier to help you better. If you are using one of our digitizers, the NI Digitizers Help file is very useful for this case. Have a nice day,
Ana P
National Instruments
Applications Engineer

Why is Start Trigger Delay not applicable?

Hardware: PCI 6602
Driver: DAQmx 7.4
Programming Environment: ANSI C
Hello All,
I'm setting up a counter output pulse generation task which is to have a start trigger. To be specific, it is a digital edge start trigger (not an arm start trigger) which I plan to use in retriggerable mode so as to get a single output pulse of specified width for every trigger edge. Currently I'm baffled as to why the Start Trigger Delay and Start Trigger Delay Units properties do not seem to apply - whenever I try to access them I get an error message saying they're not applicable to the task. The other properties of interest - Source Terminal, Active Edge, and Retriggerable - can be accessed and modified without any problems. I don't actually need the delay but am curious to know why it doesn't apply in this case. Thanks in advance.
Jeff

Hey Jeff-
You will need to make sure that you don't stop the task at any point after the first generation. Most of the examples use DAQmxWaitUntilTaskDone() to wait for a single iteration, but in your case you want to run through several iterations of the task. So, you will want to enter a loop after starting to ensure that the task continues to run in the background on the hardware. I modified the single pulse DAQmx shipping example to include digital retriggerable start triggering. The empty loop spinning is obviously not ideal, so I'll leave you the choice to implement that as necessary.
Since you're working with retriggerable single pulses, you may also want to be aware of the information in this KB.
Hopefully this helps-
Tom W
National Instruments
Attachments:
DigPulse.c ‏4 KB

Start trigger 6608

Program works in CVI 8.0
I use several 6225 for analog acquisition and one 6608 for time metering.
For simultaneous start of all devices start trigger must be set up.
DAQmxCfgDigEdgeStartTrig function allows me to connect ai\StatrTrigger of "master" 6225 with PXI_Trig0 and to connect ai\StartTrigger of other 6225 with DevN\PXI_Trig0.
So, one of 6225 defines strarting others devices 6225. For complete syncronization I must tune up start of 6608. This mean, that I shall connect PXI_Trig0 with DevN\Ctr0StartArmTrigger, where DevN - name of device 6608 in system.
What function must be applied for it? Maybe I need fundamentally other method of syncronization?
Best regards, Alexander

Hi Alexander,
To define the source terminal of the Arm Start Trigger in LabVIEW, use the DAQmx Trigger Property Node (see attached image). The C function for the same operation would be DAQmxSetDigEdgeArmStartTrigSrc(). Is this what you're trying to configure?
Regards,
Andrew W
National Instruments
Attachments:
trigpropnode.JPG ‏25 KB

Data acquisition from analog start trigger to analog stop trigger

Hi,
I'm trying to start and to stop a data aquisition by using an analog input trigger. I'm using NI-USB-6251. At input channel ai0 is a sin-signal connected. At input channel apfi0 is an analog trigger signal connected. I can start the trigger signal by pushing a button on my frequency generator. Here's a part of my code:
Hi,
ich versuche eine Messung mit einem analogen Eingangssignal zu starten und zu beenden. Ich benutze die Messkarte NI-USB-6251. An Eingang ai0 ist ein Sinus-Signal angeschlossen. An Eingang apfi0 ist der Triggereingang angeschlossen. Das Triggersignal löse ich immer per Tastendruck auf dem Funktionsgenerator aus. Hier ist ein Teil des Quellcodes:
TaskHandle taskHandle = 0;
int32 read;
float64 *data;
float64 sampleRate = 1000; //Samples per Channel per Second
uInt64 sampsPerChan = 4000; //Samples per Channel to read
int sumOfChan = 1;
double triggerLevel = 2.0;
double min = -0.2;
double max = 0.2;
double timeOutReadAnalog = 10.0;
void calculate()
DAQmxCreateTask("", &taskHandle);
DAQmxCreateAIVoltageChan(taskHandle, "/dev1/ai0", "", DAQmx_Val_Cfg_Default, min, max, DAQmx_Val_Volts, NULL);
DAQmxCfgSampClkTiming(taskHandle, "", sampleRate, DAQmx_Val_Rising, DAQmx_Val_FiniteSamps, sampsPerChan);
DAQmxCfgAnlgEdgeStartTrig (taskHandle, "/dev1/apfi0", DAQmx_Val_RisingSlope, triggerLevel);
DAQmxCfgAnlgEdgeRefTrig (taskHandle, "/dev1/apfi0", DAQmx_Val_RisingSlope, triggerLevel, 3000);
DAQmxStartTask(taskHandle);
if( (data=malloc(sampsPerChan*sumOfChan*sizeof(float64)))==NULL )
MessagePopup("Error","Not enough memory");
//set start and stop trigger
//set breakpoint here
DAQmxReadAnalogF64 (taskHandle, -1, timeOutReadAnalog, DAQmx_Val_GroupByChannel, data, (sampsPerChan * sumOfChan), &read, NULL);
I've choosen the sample rate (1000/s) and the samples per channel (4000), that the aquisition needs 4 seconds to be complete. I can start the aquisition by Start-Trigger, but I think I have a problem with the function DAQmxCfgAnlgEdgeRefTrig. Actually the array will always be filled with 4000 values. I thought I can start the aquisition by triggering once and e.g. after two seconds triggering again for stopping aquisition with result of 2000 values in the array. I hope you can help me with this problem.
Ich habe die Sample Rate (1000/s) und die Samples pro Kanal (4000) so gewählt, dass die Aufzeichnung 4 Sekunden dauert. Ich schaffe es auch die Aufzeichnung über den Trigger zu starten, jedoch funktioniert das Stoppen mit der Funktion DAQmxCfgAnlgEdgeRefTrig nicht. Aktuell ist es so, dass das Array immer mit 4000 Werten gefüllt wird.
Ich hatte mir erhofft, dass ich durch einmalige Triggerung die Messung starten kann und beispielsweise nach zwei Sekunden erneut triggere und die Messung damit stoppe und dann nur 2000 Werte eingelesen habe.
Ich hoffe, ihr könnt mir dabei helfen.

Hi Martin,
I looked over your code and noticed that you called the function without checking the returnvalue.
Try to change the line to the following:
First: define a new int32 value and call it for example: errorcode
Second: The function returns a status code, wich if it fails, includes an error code so save this code in the new generated value
errorcode = DAQmxCfgAnlgEdgeRefTrig (taskHandle, "/dev1/apfi0", DAQmx_Val_RisingSlope, triggerLevel, 3000);
and try to run the programm and read out this value.
If you got this value, please post it here and I will try to help you if I can.
Regards
Philipp

With DAQmx, how to use AO start trigger for AO/AI synchronization with finite AI sampling

I am a new user to DAQmx and I am trying to synchronize AI (finite samples) with AO in LabVIEW 7.1 using a PCI 6229 card. I want to generate a finite waveform (AO) and, subsequently, collect a finite number of voltage samples (AI). I would like to repeat the AO-AI cycles in a while loop.
Alternatively, I could use an infinite AO generation and collect finite number of voltage samples on AI but always exactly at the same spot of the AO buffer.
Using traditional DAQ and a 6024E card, I used a counter triggered by AO start trigger signal (example attached). I have problems with translating this example into DAQmx.
Please help!
Ruber
Attachments:
AIAODelay_traditional_Eseries.vi ‏155 KB

Lesley,
Thank you very much for your suggestion. Late last night I actually tried a to use AI start trigger instead of AO start trigger and it worked (since I tried the AI & AO to start simultaneously, it does not matter what triggers what), even in the loop. The devil is in details, as I had to carefully wire the number of data points and what to place inside/outside the loop.
The problem with shared clock is that I need to sample the AI and AO at different rates but using AO and AI clock separately did not seem to affect the performance.
I still want to try to use the AO start trigger (as you suggest) because I would like to delay the AI by a few ms from the AO. Is there a simple way to to that?
I suppose, switching from traditional DAQ to DAQmx requires your brain to be rewired - after playing with it for a couple of days and nights I developed a "feeling" for it. One of the differences was that, in order to use this example in the loop, one has to use 'stop task' inside and 'clear task' outside the loop.
Thanks again!
Radek Uberna

Using a Counter as a start trigger to one or more tasks

I am using the NI USB-6251. I want to configure a counter (e.g. Dev1/ctr0) at a user-specified frequency and the rising edge on this counter should act as a start trigger for an analog input task and a digital output task.
I've tried to do this by creating a task for the counter:
integStartTriggerTask.COChannels.CreatePulseChannelFrequency(
"Dev1/ctr0",
"Integration Start Trigger",
COPulseFrequencyUnits.Hertz,
COPulseIdleState.Low,
0,
integFreqHz,
0.5);
and then connecting this to the StartTrigger for the analog input task:
analogReadTask.Triggers.StartTrigger.ConfigureDigitalEdgeTrigger("Dev1/ctr0", DigitalEdgeStartTriggerEdge.Rising);
However running this gives the error:
Source terminal to be routed could not be found on the device.
Make sure the terminal name is valid for the specified device. Refer to Measurement & Automation Explorer for valid terminal names.
Property: NationalInstruments.DAQmx.DigitalEdgeStartTrigger.Source
Property: NationalInstruments.DAQmx.DigitalEdgeStartTrigger.Edge
Source Device: Dev1
Source Terminal: Dev1/ctr0
Task Name: analogReadTask
I have also tried "Dev1/ctr0/StartTrigger" instead of "Dev1/ctr0". What am I doing incorrectly? Thanks.

Hi zkhan.cimtec,
To use a digital trigger for your start task you need to use a PFI line to read a signal that is coming in. You are setting up a task that outputs a start trigger on your counter line, but you can't read off that same line to start the task since that line is already configured for output. An example of how to setup a start trigger coming into a PFI line can be found in the examples here:
<National Instruments Public>\NI-DAQ\Examples\DAQmx ANSI C\Analog In\Measure Voltage\Cont Acq-Ext Clk-Dig Start
Hope this helps,
Kevin

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

Analog start trigger for x series card gives an error?

Hi everyone,
I am having some trouble setting up an analog start trigger for DAQ using an x series PCIe card (6351)... Attached is my configuration... After reading the manual (http://digital.ni.com/manuals.nsf/websearch/08B4B2E1B5373B94862579BA006E6BAB), my understanding is that AFPI0 is a compatable analog trigger for the device; however, the vi will not run and I get an error... Although if I change the soruce to "Force" (which is ai0) it works..
Also, the device document says (pg 11-8):
"To improve trigger accuracy, do the following:
• Use an AI channel (with a small input range) instead of APFI <0,1> as your trigger source. The DAQ device does not amplify the APFI <0, 1> signals. When using an AI channel, the NI-PGIA amplifies the AI channel signal before driving the analog trigger circuitry. If you configure the AI channel to have a small input range,"
To me, this implies that I probably should use "Force" as the trigger soruce anyway (note that the instrunment is used to acquire data load cell data generated from human muscle contractions; so slew rates are relatively low compared to signals acquired from industrial tests).
Could someone please comment on these issues for me?
Regards,
Jack
LV2010
Attachments:
Untitled 1.vi ‏22 KB

Ok... I think I have answered by own question... APFI0 needs a low impedence signal to drive the terminal... I mistakenly thought this was an internal terminal or trigger...
So I should stick with using the first analog signal acquired in my DAQ device (e.g. ai0) as the trigger source?
Regards,
Jack
LV2010

Using DAQ occurrence to wait for start trigger

Hi,
I'm trying to use digital triggers to start and stop datalogging. Every time start trigger appears, new file is created and data is acquired to file until stop trigger occurs. Now I'm using set DAQ occurrence and wait for occurrence functions to wait for start trigger before creating a new file. The problem is that after first stop trigger this occurrence method doesn't work. I believe it's because AI is not cleared and configured before calling DAQ occurrence again. Number of scans acquired is not zero, if I don't clear and configure AI again? Am I right?
Do I have to clear and init AI everytime before occurrence config or is there a better way to make program wait for start trigger?
Thanks in advance,
Jakke

Hi Matt99eo,
Have you configured your device for triggering? Although you have not mentioned your device specifically, the M series user manual provides a great explanation of digital triggering. Using the DAQ Assistant, this can be configured from the triggering tab. Hopefully this helps!
Regards,
h_baker
National Instruments
Applications Engineer
Digital Multimeter Resources

Working of start trigger

i want to know how a start trigger starts the acquisition of data.please give me any example

Hello Christian,
Thank you and Best Regards,
I implemented a advance Measurement and Control system using cRIO-9074
with c-Series I/O cards( NI 9217, 9411, 9264)
I have some questions about it,
(1)- Data rate from FPGA targate to host vi is too low. how can I increase
it, when I run my host VI, sometimes all temperature sensor update at
same time and sometimes one by one, can you please give me some hint, how
can I correct it, I used two FIFOs for NI-9411 digital pulses, I put all
Digital input and all analog output and input in a seperate while loop in
FPGA targate VI.
(2)- I have to write that data to analyse for further result. I tried all
possible way to write data including wite to spreadsheet.vi, write to
text.vi, Data storage.vi, Write to measurement.vi. All this VI work
efficientlywhen it run individualy, But when I connect this VI to
writedata from FPGA host VI. than it always give empty file.
I saw your post in NI discussion forum about how to write data from
Host.vi, But still I am confuse that how can I creat a protocol between
host VI and Fpga target vi. to write the data in a file. I have nearabout
38 channel to write data.
(3)- I have to measure time difference between two digital pulses, to find
a flow rate. I am using counter for it with risisng edge shot.vi, but when
i get a timestemp when there is risisng edge for the second rising edge
how can I get timestemp. Its like i have to measure time between two
pulses, I triend waveform measurement.vi to find cycle period. but it not
worked. any other was to measure it.
I am stuck in this question since from last one month. I already followed
NI-discussion forum solution but it doesnt work. I think the way I applied
is may be wrong.
Looking forward to hear from you soon.
Plese send an additional email copy to [email protected]

CTR start trigger error - USB6343

Hi-
A digital pulse from a device in my system is connected to the gate of CTR0 (PFI9).
CTR0 is used as a quadrature encoder. My code routes PFI9 to the gate of CTR1 (PFI4)
and also defines PFI9 as a start trigger for CTR3. CTR3 is set to generate a finite
retriggerable pulse train for each digital pulse on PFI9.
My code returns error -89137 indicating that Specified route cannot be satisfied,
because it requires resources that are currently in use by another route.
Not sure what this means?
Screenshots of relevant code and error message are attached.
I am using LV2010 and a USB-6343.
Your help is appreciated !
Dar
Solved!
Go to Solution.
Attachments:
CTR3 start trigger code.jpg ‏89 KB
External trigger pulse route and CTR1 setup code.jpg ‏129 KB
Error.jpg ‏163 KB

Hey Dar,
As long as you're careful about managing your hardware resources then you shouldn't face persistent problems. It's just a matter of knowing which lines you are using at what time, and being conscious of how your signals are physically re-routed in your hardware (as I said, this is something you can check in Measurement & Automation Explorer). There are lots of great DAQ resources online through NI KnowledgeBase articles, Developer Zone articles, and community examples (found at ni.com/support). For resource related conflicts, this KnowledgeBase article is particularly good:
http://digital.ni.com/public.nsf/allkb/485201B647950BF886257537006CEB89?OpenDocument
I hope this helps! If you encounter future problems, the forums are a great way to get peer input &/or response from NI engineers.
Courtney L.
Applications Engineer
National Instruments

Routing start trigger to RTSI/PFI (NI-6110)

We've got a customer who is trying to route a start trigger to a PFI or RTSI line. He is not using LabVIEW as can be seen below and is using traditional NI-DAQ. Can you please confirm if it is possible to do using the NI-6110 and traditional NI-DAQ. I've included his email as well which contains the relevant information.
"As explained I use 2 Ni6110 cards at Wits. These cards are synchronized via a rtsi cable and operate in pre-trigger mode based on an analogue trigger on channel 1 of the master card.
Everything works well, but I need to be notified via a digital line (or RTSI line) when the trigger condition is met. At present because of the stop trigger method of configuring the card, I get notifed when the stop trigger condition occurs. This is obviously too late in the process.
The following relevant commands are used:
DAQ_StopTrigger_Config(NiDev1,1,PostTriggerPoints*NoofChannels);
Configure_HW_Analog_Trigger(NiDev1,ND_ON,LowValue,HighValue,TrigMode,TriggerChannel-1);
Select_Signal(NiDev1,ND_IN_STOP_TRIGGER,ND_PFI_0,ND_LOW_TO_HIGH);
//The following line is used to get the second card to be synchronized with the first card
Select_Signal(NiDev1,ND_RTSI_1,ND_IN_STOP_TRIGGER,ND_LOW_TO_HIGH);
On the second card:
DAQ_StopTrigger_Config(NiDev2,1,PostTriggerPoints*NoofChannels);
Select_Signal(NiDev2,ND_IN_STOP_TRIGGER,ND_RTSI_1,ND_LOW_TO_HIGH);
How can I be notifed of the start trigger condition?
I thought that something like the following could work, but I have not verified it. I need the signal to be available on a 6224 M Card:
Select_Signal(NiDev1,ND_RTSI_1,ND_IN_START_TRIGGER,ND_LOW_TO_HIGH);"
Thanks for your help.

I looked at the Device Routes and the Device Pinouts in MAX and
found that you are not able to route any of the digital lines on port 0
to the RTSI lines, only those that are directly linked to the PFI
lines. The counter lines are all directly routed to the PFI lines. In
the Device Pinouts chart it shows that the digital lines on ports 1 and
2 are directly routed to the PFI lines. Please refer to that chart and
then you can use the DAQmx Connect Terminal VI for simple easy signal routing.
To see the Device Routes in MAX: Select your device and then select the tab at the bottom titled Device Routes. Green means you can use the DAQmx Connect Terminal VI. To see the Device Pinouts in MAX: Select your device and then press the button at the top labled Device Pinouts. You can also right click on your device and it is listed there.
Vince M
Applications Engineer

PXI question: four analog ouput cards to start-trigger simultaneously

Hi all,
Here's the situation:
We have built a system that ouputs 24 analog signals using a PXIE-1073 chassis. It has 5 slots:
Slot 1:          Internal
Slot 2:          Empty
Slot 3:          Empty
Slot 4 (Hybrid): PXI-6733
Slot 5 (Hybrid): PXI-6733
Slot 6 (Hybrid): PXI-6733
As you can see, it has three analog output cards, which occupy all three of the hybrid slots. And we have two empty slots.
Our LabVIEW code is designed to output analog signals on all three cards (at the same rate) using three DAQmx tasks which start-trigger simultaneously. To do the triggering, we setup two of the tasks to start-trigger off of the first task (master-slaves style). In this manner, we can get all outputs to start at the same time. Its actually quite simple.
My question: I want to add another output card. But I am fairly I can only use hybrid slots for my application. I remember working with NI and they told me I had to use the hybrid slots to be able to get the triggers routed automatically along the backplane. Our code actually failed (error) when we used the non-hybrid slots (I forgot the error code).
Is there any way to add another PXI-6733 and have it trigger with the other cards?

I can't speak to the chassis, but I'd warn you that if you want your tasks sync'ed, you'd better share a sample clock too and not just a start trigger.  The onboard clocks will have a tolerance (often ~50 ppm, dunno for your 6733's) and their sampling instants will drift apart from one another over time. In fact, I rarely both with triggers at all for syncing tasks & boards. I'll usually *only* share a sample clock, and then make sure I start all the slave tasks before the master whose sample clock is being shared.
Good luck on your real question though...
-Kevin P

Using the same wire for positive edge start trigger and negative edge stop trigger for 6533

I would produce a start trigger for an external data source to start them.
Emediatly after this starttrigger this source produces a trigger Signal.
I would like to use this trigger Signal as an extern trigger which should provide some functions:
1. on the positive edge of the Signal some pattern should read in with an external clock.
2. on the negative edge of the trigger signal this process should stop.
I would do this with CVI

Hey Schicki,
I have included two links below that should help you with your application. The first one is setup to perform digital pattern I/O with an external clock in CVI. The second shows how to incorporate start/stop triggers in digital pattern I/O operations. You should be able to combine parts of these two programs to complete your application.
NI 6534 Double-Buffered Pattern Generation, External Clock -- CVI
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3E7FD56A4E034080020E74861&p_node=DZ52321&p_source=External
Output Digital Data from a Buffer to a Group of Two Digital Ports Upon a Digital Start Trigger
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3EA4556A4E034080020E74861&p_node=DZ52321&p_s
ource=External
I hope this helps.
Regards,
Todd D.
NI Applications Engineer

Arm start trigger

Similar Messages

Maybe you are looking for