Time measurement between counter output my device and analog input

Hello!
I'm trying to measure the time to generate a digital pulse train on the counter output, that goes to a frequency converter that controls a motor. So I think it'd be the best way to wire the output of the frequency converter with an analogue input and make a timestamp before I generate the pulse and a timestamp when I recognize the singal, but I think that wouldn't be a serious measurement ?
What's the best way to measure the time?
kind regards peter

hi there
well, there a several ways to do this. the problem with the software - timestamps is the minimal resolution of 1ms. i'd suggest:
- wire a copy of the digital pulse train to an analog input channel
- wire a copy of the frequency converter to another analog input channel
- create an analog input task with the two channels (the sampling rate defines the timing resolution,make sure to acquire enough samples to see the response signal)
- start this task
- send the digital pulse train
to optimize your acquisition you can use another copy of the digital pulse train as a start trigger for your analog acquisition.
-> then you'll see the digital pulse train on one of the analog channels and the frequency output on the other one. both channels have the same time axis with a resolution defined by your sampling rate (~us depending on your hardware). then you can analyze the data.
search the example finder for examples of how to create tasks and triggers.
Best regards
chris
CL(A)Dly bending G-Force with LabVIEW
famous last words: "oh my god, it is full of stars!"

Similar Messages

How to use counter output pulses to trigger analog input?

Hello all,
I hope the kind people using this forum can help me, a lowly beginner LV programmer! I have been attempting to create a VI that produces a user defined number of TTL pulses, separated by every n seconds. Each TTL would be outputted to a stimulator, which in turn generates its own TTL. Using the stimulator-generated TTL, I would like to trigger finite analog data acquisition (e.g. for every TTL, trigger the collection of a data sweep that contains 4000 samples (collected at 4000 Hz), with 1000 samples collected pre-trigger. I would like to also be able to see each data sweep as it is triggered on a chart. As I understand things (lots of online/book/forum reading), I should be using the counter output to generate my TTL pulses, and syncing each counter produced TTL with analog input, as well as using a reference trigger. Also, the AI part should be started first, so that I don' t miss any counter outputs. If it matters, I also need to use one of the AI channels to acquire the TTL, so I can see my stimulator-induced responses to the stimulator in time.
I am able to generate the TTL pulses from the counter output, but I am having a problem with the AI part. I am unsure how to sync the counter output with AI. Also, since I need to acquire pre-trigger samples, I would be needing to acquire samples continuously, but when I set 'continuous samples' on daqmx timing, the VI doesn't work (hence why's its set to 'finite samples').
I hope someone out there can help, as I have been at this for what seems ages, with limited success. I am using a USB-6259 and LabView v8.2. Thanks!
Attachments:
RC001 v_1.vi ‏49 KB

Hello,
Due to the fact that analog tasks themselves are not retriggerable, a
pulse train produced by a counter is always used as the sample clock
for the analog input task in order to recreate a retriggerable effect
for analog input. This can be done by creating a finite pulse train set
to retriggerable using the DAQmx Trigger Property Node, or the pulse
train could be continuous and just be gated by another signal. Neither
of these methods can be properly applied in hardware to create a
retriggerable reference trigger. You can however implement something
similar in software by just stopping and restarting your reference
triggered analog input task within a loop. There will be some delay
between when the task is stopped and restarted, as these events require
software intervention, but if there is enough time between when each
trigger signal is generated, there should not be any noticeable delay
or missed samples.
I have attached an example of this!
Mark B
===If this fixes your problem, mark as solution!===
Attachments:
RC001 v_1mod.vi ‏25 KB

How to combine Digital Output, a delay and Analog Input in a fast loop

I need to develop a process loop that runs at least at 250 Hz that performs a Digital output, than a delay of 50 microseconds and than an analog input of all the channels. All will be done using ATI MIO 64E3 card. Of course, the acquired data will be processed, displayed and saved. The loop will be running for several minutes until user stops it.

The fastest and most precise timing will occur if you use hardware timing. You can apply hardware timing to analog input on the E Series boards, but not the digital lines. Let's focus on the analog input first. Continuous waveform scanning uses a scan clock, which can be the board's internal one or an external one which you apply. If you want to scan all the channels 50 microseconds after a digital rising edge, then you need an external signal to signify that scan clock.
The E Series boards also have 2 counter/timers onboard that you can use for this purpose. You can set up a retriggerable pulse generation operation, where the counter receives a trigger and then on the user specifications, produces a pulse. You can have that route to the analog input scan clock.
The trigger signal for the counter is that digital pulse. As I mentioned earlier, there is no hardware timing for the digital lines on an E Series board. We do have other digital boards (653x family) that have hardware timed operations if precision is important. If you are satisfied with software's resolution (in the milliseconds), then you can call the E Series board digital function in a loop with a software timer. That digital line can route to the counter to act as the trigger.
So, on the programming side, you can have three separate and independent operations in parallel. One is for the digital function to output on that line every so often. Another is for the counter set at the retriggerable pulse generation. The last is for the analog input. I will describe this in terms of LabVIEW, but it can be done in a similar fashion with the NI-DAQ function calls or Measurement Studio.
The digital examples are in the LabVIEW >> Examples >> Daq >> Digital >> E-Series directory. The Generate Retriggerable Pulse example is in the LabVIEW >> Examples >> Daq >> Counters >> DAQ-STC directory. The E Series boards use the DAQ-STC timing chip.
Go to the LabVIEW >> Examples >> Daq >> anlogin >> strmdisk.llb directory and start with the Cont Acq to Spreadsheet File. This shows how to continuously acquire data and stream it to disk while displaying the data on a chart. Streaming to disk is the efficient way to save data while you are acquiring, as it eliminates the overhead of always opening and closing the file through the iterations of the loop. This saves to a file that can be opened by other applications (Excel, Word, etc.), but it is not as fast as writing to a binary file, which must be opened and read back through LabVIEW. However, for your ~250 Hz rate, it should be fine. Then, go to the LabVIEW >> Examples >> Daq >> anlogin >> anlogin.llb and look at the Acquire N Scans -ExtScanClk example. This shows how to apply the scan clock. Here, the AI Start that you saw in the previous example is replaced by 4 VIs (3 AI Clock Config's and the AI Control). Make those changes to the first example and then add a constant 0 to the AI Control parameter for total scans to acquire. That specifies the continuous operation. The File >> VI Properties >> Documentation menu item of the example describes the physical connections.
If you aren't using LabVIEW, use the NI-DAQ User Manual and the NI-DAQ Help file installed on your machine. You can look at your AT E Series User Manual at the http://www.ni.com/manuals pages for more information on the hardware. Also, if you want to route those signals internally on the board, you can find some entries in the KnowledgeBase at the http://www.ni.com/support pages.
Regards,
Geneva L.
Applications Engineering
National Instruments
http://www.ni.com/ask

How can i synchronize analog output and analog input timings to generate and measure voltage at the same time.

how can i synchronize analog output and analog input timings to generate and measure voltage at the same time.

Read this Tutorial
http://zone.ni.com/devzone/cda/tut/p/id/3615#toc3
And also refer to this link where You have repeated this question.
PS: Please stick to one thread. That way, its easier to keep track of your query and answers

Home Sharing not working between wireless PC's / devices and ethernet wired PC's on the same router.

Home Sharing is not working between wireless PC's / devices and ethernet wired PC's on the same router. I installed a new Verizon FIOS ActionTec MI424WR GigE wireless / ethernet router, replacing the original FIOS router. With the old router Home Sharing worked fine across and among all iOS and Windows wired and wireless devices. With the new router Home Sharing works between and among the Wired PC's but not between the wired PC's and the Wireless connected PC's or iOS devices. Home Sharing also works between and among the wireless connected PC's and iOS decices but not between them and the wired PC's.
Only the router was changed. No changes were made to any of the devices except all were updated with the latest version of iTunes 10.7.0.21 and the iSO devices were updated to iOS vrsion 6.01. Three PC's are wired and all are running Windows 7. There also is a Windows Home Server connected to the router by ethernet port. It does not run iTunes but does provide WebDAV services to my iOS devices. This works fine. Two PC's are wireless, one running Windows 7 and one running Windows 8. All of the PC's are connected to the same (new) router via it's ethernet ports and it's wireless access point. Two of the wired PC's are connected via a high-speed ethernet hup that is connected to the router (Home Sharing works fine between the two PC's on the hub and the PC on the router). All wired and wireless devices on the router are visible and members of the router's Home/Office virtual network.
All of the PC's are visible in the Windows network and all shared files are accessable from all PC's, both wired and wireless.
Obviously the router seems to be the issue, something between the ethernet and the wireless access point components. I checked the settings and found nothing that would prevent Home Sharing between the wired and wireless devices. There is no setting that isolates the wireless network. I have done the following:
Read the router user manual and checked all the settings
Rebooted the router and tested.
Turned off the router's firewall and tested.
Home Sharing is turned on all the devices and all use the same Apple ID.
Restarted iTunes and tested.
Verified iTunes is "Allowed" in each PC's firewall.
Again, I can Home Share between the two wireless PC's but not between either of the wireless PC's and any of the wired PC's. I can Home Share between my iPads and iPhones and either of the two wireless PC's but not with any of the wired PC's. I can Home Share between any of the wired PC's but not between any wired PC and a wireless PC or iOS device.
I hope someone may have had a similar problem and has a fix suggestion. I'm stumped! I have a;so contacked ActionTec and awaiting an answer.

Solution from ActionTec is:
Log into your router.
Click the Advanced icon
Cclick Yes
Click on the IGMP Proxy
Select Disable
Click Apply

ELVIS Scope and Analog input triggering

Hi everyone,
I'm trying to read two waveforms, one from the analog input and one from the scope. These waveforms are coming from two sides of a voltage divider and should always be in phase. But I think that there might be a triggering problem. When I change the frequency of the input waveform, my measured waveforms go out of phase.I have programmed each express VI to trigger off of the SYNC.
I can't use analog inputs for both measurements because the sampling rate is too small. I can't use the scope for both inputs because one of the waveforms is a differential measurement.
Any help would be appreciated, thanks.

Hi, I looked at the ELVIS Hardware User Manual and noticed that you have 12 channels that can be used as differential, Reference single ended or non reference single ended. Unless you have them all busy I don't see why you can't use the analog inputs. About the sampling rate, it will be determine by the M Series DAQ device that you are using and the source of the signal. It is a good practice to sample, at least, 10 times faster than the frequency of the input signal. The documentation of the card should show what the maximum sampling rate is.
Now, Open the example called "Multi-Device Synch-Analog Input-Cont Acquisition.vi" at the NI Example Finder under Hardware Input and Output»DAQmx»Synchronization»Multi-Device. If you get the same results shown in the picture then you need to analyze if the voltage divider is affecting the phase.
For more information about synchronization check the article called "Synchronization Explained".
Good luck!
Alejandro | Academic Program Engineer | National Instruments

Can I use time capsule as a back-up device and not use the wireless?

Hello. I have recently had many issues with a new Time Capsule.
My question is : Can I use my TC as a back-up device and not wireless while I am using my Lynksys router as my WiFi device? Thx.

Can I use my TC as a back-up device and not wireless while I am using my Lynksys router as my WiFi device?
Yes, turn off the wireless on the TC if you want to do this.
Open AirPort Utility, click on the TC, and click Edit
Click the Wireless tab at the top of the page
Change Wireless Mode to Off
Update to save the new settings

Network printers take long time to show in control panel - devices and printers

G'day,
an annoying effect both on Win 8.1 and Win Server 2012 R2: after installing/connecting a network printer for a user, it takes about 10 minutes (sic!) till printer is shown in devices and printers...
Printer is shown and can be used immediately after connect in word/notepad, but properties of printers can only be managed via devices and printers. Work around for setting standard printer: open notepad, click
print and right-click printer.
But we have to choose a special printer profile, which cannot be done else than devices and printers.
Sometimes even previously installed printers do not show for minutes after logon...
Restarting spooler: no effect
Changing drivers: no effect
Printers are Konica C554 series and 4700P series with Konica PCL drivers.
Print server for network printers in Win Server 2012 R2 (VM on Hyper-V 2012 R2)
No other network issues.
Thanks and regards.
McButtonn

Open the printer folder the spooler team built. It's hidden but available and will list just the printers not the devices.
If the print shows up immediately, the spooler has the information. You will be running the shell command to invoke the old UI.
https://social.technet.microsoft.com/Forums/windows/en-US/8d69181f-3b9f-43c0-ba6d-ba99fe5fc413/printer-visible-in-print-dialog-but-not-visible-in-devices-and-printers-revisited?forum=w7itprohardware
Enumerating into the Devices and printers UI is then the issue.
thanks
Alan Morris formerly with Windows Printing Team

Logic Mics, Aggregate Devices and The Input Issue

There is a lot of discussion about Logic's inability to accept simple microphone inputs, and I ran into this for two frustrating DAYS of trying all the things in the Logic Express 8 Docs to fix it—to no avail.
But now it is solved, so I'm trying to create a DEFINITIVE list of steps and principles here so others may quickly blast past this issue.
The equipment I have seems to be emblematic to the problem. The Blue Snowball is one of those USB mics that simply doesn't automatically show up in Logic's Preferences > Devices > Core Audio >Device list. The fix for this is never mentioned in the Logic manual or Getting Started docs that I can find. There is a passing reference on page 100 that is virtually zero help, and does not bother to mention how this Prime Gotcha can bring you to your knees.
Principle #1: Logic uses the Preferences > Devices > Core Audio >Device (list) process to identify which microphone you can record with. The list has to have in it an entry that makes sense for both the incoming audio and the playback path that Logic uses to feed earphones or an external monitor.
Normal items on that list look like this:
Built-in Output/Line Input
Built-in Output/Digital Input
Built-in Line Output/Input
Built-in Line Output/Digital Input
Built-in Digital Output/Line Input
Built-in Digital Output/Input
The Built-in Output is the computer’s inner speaker or headphones. The Built-in Line Output is the computers stereo jack for feeding to an amplifier. The Built-in Digital Output is the fiber optic feed that can also feed an amp with up to six parallel audio channels (okay, 5.1 channels).
Nothing on that list will show a fully functional USB microphone that is being viewed on the computer’s System Prefs > Sound > Input page, even though the metering dots there show that the computer sees a live, active microphone.
Selecting the Mic in the Sound prefs page does nothing to pass it on to the Logic > Preferences > Devices > Core Audio >Device list of selectable items. This is frustrating, since GarageBand sees the live mic without any problem, but GB is a simpler program that has fewer options while Logic has many other potentials, so a one-size-fits-all solution may not be its best default setting.
To get the mic into Logic, you have to go into the Audio MIDI Setup utility program where a peculiar option appears that is called “Aggregate Device”.
This keyword is not found in the Mac docs, and understanding it seems to be a big secret. Even the Audio MIDI Setup help page will show you how to find it, but not how it works or how to use it for Logic. Ahem.
You open Audio MIDI Setup and under its header bar Audio is only one item, sure enough, Open Aggregate Device Editor. That opens a window that has two sections, an upper window with Aggregate Devices / In / Out across its top, and a lower window that shows all the options that the computer is aware of. The lower window is called “Structure:” and columns show Clock / Use / Audio Device / In / Out / Resample.
A default item “Aggregate Device” shows in the top panel, and you can add others and double click on one to change its name. You can make many variations here.
By default these will be present:
Built-in Line Input
Built-in Digital Input
Built-in Output
Built-in Line Output
Built in Digital Output
At the bottom of this list any other audio input devices that are plugged into the computer should show up. If they can be seen in the System Prefs > Sound > Input page, they’ll be here, too.
When I plug my Blue Snowball USB mic into the computer, it shows up here as Blue Snowball.
You create an Aggregate Device by clicking on your sound source, in my case, the Blue Snowball, then adding one or more other options.
When you click the Use check box for any entry, it pops to the top of the list.
Principle #2: An Aggregate Device is used by Logic to “see” both an audio input and an audio output path at the same time. The Device you’re creating at this point must include an input Audio Device AND at least one Output item to be fully functional for Logic. A Help page in Audio MIDI Devices called “Combining multiple audio devices” explains this in bare bones, but you can’t see that help page unless the Audio MIDI Devices utility is open.
In my case, I’ve checked the Blue Snowball and Built-In Line Output, so I can use that combo in Logic to define where the mic is coming from and where the Logic audio output should go to my line-input amp and speakers.
In the Audio MIDI Setup utility, simply selecting the Blue Snowball as the “Default Input:” device and/or the “Properties For:” options shows that the Audio Output area of the page has this cryptic message: “Output is not supported.”
At this point, you’re almost ready to go, and you can close the Audio MIDI Setup utility. But there is at least one more “gotcha” to conquer.
Principle #3: Logic ONLY looks for its list of usable Core Audio Devices when it starts up. If you have it open right now, all the choices made for Aggregate Device will not show up as selectable. Save any work in Logic, shut it down, then boot it up again.
Now you can use Logic's Preferences > Devices > Core Audio >Device list to see your Aggregate Device. I’ve named mine “Snowy Line Out” to trigger my recognition of what it contains. Another one is called “Snowball + Line + Digital” and it has both line and digital outputs aggregated to the Snowball mic input.
You can make one in the Aggregate Device Editor that combines a microphone plus earphones (Built-in Output) plus Line and/or Digital Outs, too. You'll have to switch among them in Logic as you work, but each will carry the live mic direct to recording.
I hope this gets you through the frustration of not knowing what to do when confronted with the lack of clear docs and complete steps to get a USB mic or other seemingly opaque input issue. Feel free to add to this so others in my former state of bewilderment can gain understandings.
If Steve Jobs were to encounter the level of opacity, ambiguousness and frustration that setting up a simple USB microphone can create in Logic, you can bet that the several programs and their intimate interdependency would be either automated or fully explained in the documentations that followed his fiery analysis of the issue.

I don't know of another way to get the Blue Snowball USB mic to show up in Logic. If you can do it without having to go through the Aggregate Device route, feel free to post here how to get that to happen.
I didn't have a different mic available when I started trying to do what seemed to be the simplest of things -- record and play back an audio track -- and nothing else seemed to work.
There are a lot of Aggregate Device threads around here, many associated with Blue Snowball, Blue Snowflake and other things, but none of them laid out the principles of how Aggregate Device Setup needs to work or what to do to force it into compliance.
As I said, the clues in the Logic docs and in-mac docs are minimalist, at best, none of them bringing instant head slaps of success readily.

PC as a bluetooth Device and accept input from other devices

I need to set my PC up as a bluetooth device by use of a bluetooth dongle connected to my PC. I need to have a program running on my PC that will detect other bluetooth devices and connect with them, accept input from them. Please help me do this. anyone got code for this? Thank you a gazillion in advance !! :)

There's no way to do is with standard Java as far as i know. You'll have to use JNI to use native libraries.

How to use both digital and analog input modules in the same worksheet - MCC USB1208LS

Dear all,
Hi, I am Imran. I am using MCC USB1208LS. I have created the worksheet using digital input module as below and able to execute (run).
But when i add another analog input module in the same worksheet and executes, An error Message pops-up as in the below image
I have connected temperature sensor sognal to the analog input of USB1208LS. When using analog input alone in the worksheet, it indiates the actual values.
is any black box solve? please guide me. I am attaching in images
We already placed a purchase order for USB1208FS. Will it sort out my issues?.
Thanking you,
Imran Mohamed.
Attachments:
present worksheet digital input only.JPG ‏67 KB
with analog input module.JPG ‏81 KB
error menu.JPG ‏77 KB

Hello Imran,
the USB-1208LS is not capable of running concurrent operations such as an analog input scan and ANY digital Ins, Outs, counter reads, or analog outs. In Dasylab, the 1208LS is scanning, and nothing else from that particular device can be requested of it while that is happening.
Yes, using the 1208FS will resolve some of these issues.
Please refer to the ULHELP.CHM file installed on your computer in c:\program files\measurement computing\daq for details on this issue, et al.
also I recommend you send your MCC/DASYLab requests for support to [email protected] as MCC staff (that includes me) does not normally monitor NI's Developer Zone.

Newbie: 6020E (USB) slow performance with mixed digital and analog input

Hi,
I'm using a 6020E to do analog and digital input, and I'm getting very bad performance.
Please note that doing IO in Labview is new to me!
I have read the post about 6020E slow performance, and it says I should do buffered IO.
Can anybody point me to some DOC or SAMPLE that actually shows or explains how one should do this. I need to read several digital IO lines (which I can combine in one port-read), and several analog inputs.
Seeing how slow the reading on the 6020E is, I am amazed there is only one post that deals with this issue.
I would be satisfied to get the 6020E into some sort of continuous read mode so that whenever I need data, I get the latest reading right away.
thanks,
Peter D'Hoye

Hi Peter,
Your cannot do buffered digital I/O with your daqpad. It doesn't have that capability. You can only make direct software calls with digital read/write from/to your port. So your digital IO is completely software clocked and not hardware clocked. The example you are trying is only for specific Simultanuous sampling boards or now also for M-series boards that are able to do correlated DIO.
Use the Cont Acq&Graph Voltage-Int Clk.vi example for your analog measurements. (NI Example Finder) For your digital IO you can only use the examples like Read Dig Chan.vi, Read Dig Port,...
There are indeed some slow performance issues with single point I/O Operations, that is correct.
Check the explaination below:
DAQPads are offered for the Universal Serial Bus (USB) and the IEEE 1394 (also known as FireWire). Both of these standards use a high-speed serial communication protocol between the computer and the device with a bandwidth up to 12 MB/s for USB and 400 MB/s for FireWire.
During a single point operation, the DAQ device requires a complete set of configuration commands. This is done through serial communication (USB or FireWire), making the process slower than in a PCI-based board. The speed obtained for single point operation in a DAQPad is system dependent; this means that your computer processor, memory, bus speed, and other factors alter the speed at which you can do single-point operations with a DAQPad.
For example, on the DAQPad-6020E, timed non-buffered analog input operations are limited to about 50 Hz. At higher rates, the software may become unresponsive. On a FireWire device, you can expect stable operation around 3,000 Hz. But again, these figures are system dependent.
Regards.
JV
NI

Synchronize hardware timed buffered counter acquisition with buffered analog input acquisition

LV7.1
DAQmx
PCI-6036E
SC-2345
Windows 2000
Greetings.
I am simply trying to synchronize AI readings with readings from one Counter.
I am trying to perform buffered analog input synchronized with buffered counter acquisition.
I'd like the AI acquistion to trigger the Counter acquistion.
I'm currently setting the Sample Clock Source for the CI Cnt Edges Task to "Dev1/ai/SampleClock" but when I try and set the source for the "DAQmx Trigger" I can't seem to select one that works. I assumed that the source should be the "Dev1/ai/StartTrigger" but that produces and error as does selecting any of the PFI's.
I'm new to DAQmx and didn't have any luck with the examples or what's been previously posted.
Thanks for your help.
Attachments:
Initialization.jpg ‏84 KB

Gentlemen-
All of your initial help was great. I had some noise on my counter lines so switched from an E-Series card to a PCI-6259 M-series card in order to use the counter digital filters.
Now I can't get a corellated buffered counter and buffered analog input acquistion to work. This same code worked fine on an E-series card but it doesn't on the M-series.
I verified that the source and gate of the counter are working properly using the test panel and a external function generator.
But when I run the attached code I get no data out of the "Counter 1D U32 NSamples", only an error saying that the timeout of the function was reached and no count data became available. Am I missing the specification of a another clock or something?
The counters also work fine using the M-series example code "Count Digital Events (M-Series DAQmx) but this is not a buffered acquisition.
Any help would be greatly appreciated.
Steve
Attachments:
Sample_Code.jpg ‏136 KB

NI DAQmx Digital Output Trigger To Start Analog Input Task

Hi everyone. I am using the NI DAQmx VIs to set a digital output line low (boolean '0'). I want to begin reading an Analog Input voltage (Start Analog Input Voltage reading task) right after the digital output line is set low. I am using the DAQmx Start Trigger (Digital Edge).vi to try and do this. I have the digital edge to trigger off a falling edge since the digital output line is being set low. I am using "do/SampleClock" as the source into the DAQmx Start Trigger (Digital Edge).vi.
I don't have the DAQ card (PXI 6229) since someone else is using it but I wanted to write up the SW so that when it becomes available I can have SW to try out.
I have attached the VI. Am I setting up this VI correctly?
Thanks!
Attachments:
Trigger AI Task Off DO Edge.vi ‏32 KB

I think you are going to have to wire that Digital Output to a PFI line on the card with the Analog Input(s). You then trigger on that PFI line.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
Unofficial Forum Rules and Guidelines

Simultaneous serial and analog input DAQ?

Need to sample from the serial port and 4 channels
of analog input at the same time. Figured I need
to use an internal clock to sync the aquisition
since the serial port response delays every so
often. Does anyone know how to sample from an I/O
port and a DAQ card at a consistent sampling
frequency in LV? Any help would be greatly
appreciated.
Sent via Deja.com http://www.deja.com/
Share what you know. Learn what you don't.

[email protected] wrote:
>
> Need to sample from the serial port and 4 channels
> of analog input at the same time. Figured I need
> to use an internal clock to sync the aquisition
> since the serial port response delays every so
> often. Does anyone know how to sample from an I/O
> port and a DAQ card at a consistent sampling
> frequency in LV? Any help would be greatly
> appreciated.
You don't mention what kind of data rates you are talking about. I have
put together several systems that combine time-stamped serial and daq
channels, but in all cases, the serial data was running at around 1 Hz.
The daq channels were often running much faster (100Hz to 1KHz). If
your channels fit this description, then it is possible to synchronize
your data (more or less)
. You can use software timing to set up the
slow loop and acquire the serial data, and used buffered A/D to read in
the appropriate daq channels. The synchronization isn't perfect, but
may be "good enough".
Best of luck,
Dave Thomson
David Thomson 303-499-1973 (voice and fax)
Original Code Consulting [email protected]
National Instruments Alliance Program Member
Research Scientist 303-497-3470 (voice)
NOAA Aeronomy Laboratory 303-497-5373 (fax)
Boulder, Colorado [email protected]

Time measurement between counter output my device and analog input

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