Synchronizing two counter frequency inputs with multiple analog inputs

Hello all,
I'm fairly new to LabVIEW and I'm trying to collect data from multiple sources with synchronized timing on the acquisition but I'm having trouble figuring it out. My problem is that I've got two counter frequency inputs, one optical tachometer reading one pulse per revolution, and a max machinery flow meter with a k factor of 12000. I can't seem to figure out how to sync the timing with my multiple analog inputs. I've been attempting to get the tachometer to sync with the analog inputs first by following the example linked here. (https://decibel.ni.com/content/docs/DOC-10785) So far each time I run it I either get a timeout error on the DAQmx read or a "Multiple sample clock pulses were detected" error (see attached image). It seems if I slow the sampling rate way down to say 10 hz and ensure that the tachometer signal is over 800-1000 RPM (13-17 Hz) before starting the VI then the program will run without errors until the RPM drops below that threshold then the "Multiple sample clock pulses" error occurs. The code is attached below.
Does anyone know of a more effective way of syncing counter frequency inputs with analog inputs? I'd like to have a VI that can show 0 RPM (and eventually 0 flow as well, but I think I need to figure out the timing of one counter before I add another as it seems I can't have two counters in the same task). Any help on this would be greatly appreciated.
LabVIEW version 13.0
cDAQ-9178 Chassis with NI 9401 for the two counter inputs and NI 9205 for the analog inputs.
Thanks!
Richard
Solved!
Go to Solution.
Attachments:
SimpleDAQ.vi ‏44 KB
LV_Error.JPG ‏31 KB

Maybe third times the charm?
So I've finally got a good handle on why the VI is having problems at low RPM though I'm somewhat embarassed how long it took me to do that
Because I have the counter time synced to my Analog input task if it doesn't see at least two pulses between the two clock pulses set by the analog input task I get the -201314 "Multiple sample clock pulses" error. This seems fine at first as it just sets a minimum RPM that I can measure and it's well below the area I'm interested in so no problems there. I tried a simple error handler that would clear the error when it happend assuming the loop would keep iterating until the RPM went above that minimum at which point I would get a signal again. This is not the case, the read function just continues to spit out the -201314 error even after the RPM is back in the readable range. So then I tried adding two case structures so that when the error occured it would stop the task, clear the error, and then start the task again on the next loop iteration (Code Attached). This also doesn't work as the error shows up again on the stop task and then AGAIN on the start task on the next loop iteration. It seems this error is not actually being cleared and once it happens it stays with the task regardless of what the error cluster is carrying.
Anyone have any ideas? The only solution I can think of is to just clear all tasks and recreate them each loop iteration until the RPM is readable again but that strikes me as a horribly clunky solution.
Richard
Attachments:
SimpleDAQ_1_Start Stop.vi ‏48 KB

Similar Messages

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

Count(*) , group by with multiple columns from multiple tables involved

Hi all,
I am relatively new to SQL.
Currently I have these few requirements, to display quite a number of fields from 3 tables for display of report.
In my query I need to:
1.) count(*)
2.) select quite a number of fields from table 1,2,3
However when count(*) is used, grouped by has to be used to.
How do I actually use group by with so many columns to be selected?
I have actually used the query below, but the count(*) returns 1, the correct output should be 3 instead.
select count(*), table1.col1, table1.col2, table1.col3, table2.col3, table2.col4, table2.col6, table3.col1, table3.col4, table3.col5
from table1, table2, table3
where
<conditions>........................
group by table1.col1, table1.col2, table1.col3, table2.col3, table2.col4, table2.col6, table3.col1, table3.col4, table3.col5
I know this group by statement looks very unrefined. How can I select multiple fields from different tables, and yet get the count(*) correctly?
Thank you so much for your time.

Hmm yes it actually does return count as 1 for each row. But there are 3 rows returned. E.g.
ctr table1.col1 table1.col2 ..........
1 value1 value1
1 value2 value3
1 value3 value4
If I put the count(*) outside, it returns 3 , the correct output
ctr
3
select count(*) from
select table1.col1, table1.col2, table1.col3, table2.col3, table2.col4, table2.col6, table3.col1, table3.col4, table3.col5
from table1, table2, table3
where
<conditions>
group by table1.col1, table1.col2, table1.col3, table2.col3, table2.col4, table2.col6, table3.col1, table3.col4, table3.col5
Thus I was wondering if it was the group by of multiple colns that resulted in the count stucked at value 1.

Difficulty synchronizing data from VISA resource with data from a physical channel

Essentially what I'd like my program to do is control the electrical power going (sourcing either current or voltage) into a light and measure the intensity of the light at a given power level, and then do this automatically for ~1000 increments of the source voltage/current.
One of my lab partners made a program a while back which does what we want("LIV Sweep Rev.vi" the first image in the link at the end of this post), but it's a bit sloppy: the program is able to interact with the power supply (connected directly to the computer via USB) and make it turn on, increase the voltage/current, and record the "IV" characteristics just fine. The program can also interact with the light detector (connected via NI-BNC 2110) and gather the photocurrent data. The problem, however, is that the data wouldn't be in sync. The photocurrent data for when the light was actually supplied with 1V would be improperly recorded in the cell for when 2V are applied to the light. To fix this problem my lab partner added in a time delay so that the detector will pause for ~0.35 sec (user-specified in front panel) before gathering data.
The program works, but I figured there had to be a better way. The thing about the timing, however, is that it changes from run to run. Sometimes a delay of 0.45 s works well, and other times the power supply will have shut down while the detector is still gathering data (and thus we miss the low end of the sweep). Other times the detector will turn on too early, which will cut off the high end of the sweep.
(Note: I have next to zero experience with LabVIEW, but I know a little bit of java, so I understand most programming jargon)
I spent all day yesterday trying to find out how to synchronize two data aquisitions (my attempt is shown in the "LIV SweepSummerDuncanRev3.vi" in the link at the bottom, 2nd image) but I'm running into trouble when I try to trigger the sample clock using the VISA Resource Name for the power supply.
The programs can be viewed here:
http://imgur.com/a/Up3eS
I'd really appreciate any and all advice that you folks have to offer!

Change the code such that rather than using a ramp from your power supply, just output a single value. Then do your measurement and then step to the next value in your ramp.
You can use a State Machine (SEarch if you do not know that term in LV).
Some gear will allow specifying a ramp driven by an external clock. If you widget can handle an external clock/trigger that approach could run faster.
Without hardware to syncronize the various sub-systems you would have to resort to using a RT OS and depending on the instruments, even that could be hit-n-miss.
So re-code to step-measure-step-measure etc.
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Synchronizing Torch 9800 contact list with my Playbook

I am trying to avoid retyping all my contacts on my Torch 9800 into the Contact on my Playbook. Is there a way to port them from my phone to the Playbook and then sychronize them so when one changes, it automatically changes the other?

Hey pratiktnm,
Welcome to the BlackBerry Support Community Forums.
Thanks for the question.
Are you setup on a BlackBerry Enterprise Server? With the Desktop service book appearing it seems you were on one. If you are still on a BlackBerry Enterprise Server, I would suggest creating a full backup with BlackBerry Desktop Software: www.blackberry.com/btsc/KB33505
Then proceed with a security wipe by going to Options>Security>Security Wipe and then contact your network service provider to generate a new Enterprise Activation password. Then proceed with the enterprise activation by going to Options>Advanced Options>Enterprise Activation.
Once the activation is completed, test out the wireless synchronization of the contacts.
Let me know if you have any more questions.
Cheers.
-ViciousFerret
Come follow your BlackBerry Technical Team on Twitter! @BlackBerryHelp
Be sure to click Like! for those who have helped you.
Click Accept as Solution for posts that have solved your issue(s)!

Two-way forest trust between two (single domain) forests with multiple identical user ID's

Domain and forest levels - Windows 2003 (they both have one 2008 R2 DC)
We need to create a two-way forest trust between two separate single-domain forests. The problem is that these two forests already access each others resources through a S2S. Users have the same login names and passwords on both forests/domains. Now, we
are combining their infrastructures and need to set up a trust. From what I'm reading, you can't create forest trusts if you have the same SIDs, user ID's, or computer name in each of the forests.
I'm looking into AD migration tool to copy the userSIDs (SID history?) between forest/domain, deleting the user ID's in the domain we migrated from, and then setting up the trust, but I'm leery about doing it this way as there is no easy 'recovery' should
something go wrong.
Any suggestions for the easiest way to setup this forest trust?

Hi,
To eliminate your worries, two user accounts have the same user name doesn’t mean that they have the same SID. Moreover, the user’s SID remains the same even after it has been renamed.
The SID for domain account/group consists of a
Domain Identifier and a Relative Identifier. Domain Identifier is unique in every domain within a forest, and a Relative Identifier is unique within domain. It is unlikely that two user accounts with or without the same account
name from two forests have the same SID.
The Technet article you mentioned is talking about duplicate SIDs instead of “duplicate computer name or user account”, I will submit a change request to Microsoft about this.
If there are duplicate SIDs when you create forest trust, you need to delete one of them as the article guides.
Here are some related articles below for your references:
How Security Identifiers Work
http://technet.microsoft.com/en-us/library/cc778824(v=WS.10).aspx
Security Identifier Structure
http://technet.microsoft.com/en-us/library/cc962011.aspx
Security Identifier
http://en.wikipedia.org/wiki/Security_Identifier
I hope this helps.
Amy Wang

Synchronizing Palm Treo 680 Unlocked with Outlook 2003 on Windows 7

After 2 full install and reinstall of Palm 6.2 I cannot synch my Outlook 2003 and Palm Treo 680
Hotsynch Journal says everything has synchronized correctly but new meetings and task changes in one platform do not appear on other platform.
There is an error mentioned for file PmTrcae Database (Protocol error 4004)
I must mention that Installation process seems to drop after announcing that first hotsynch will be performed, it never does, I had to start it manually from the Treo.
Will there be a proper Windows 7 version published?
Post relates to: Treo 680 (Unlocked GSM)
This question was solved.
View Solution.

gallinago wrote:
I downloaded v.6 onto my new Windows 7 computer. When I try to hot sync, I get a window stating that the driver is missing and I cannot find a driver on your site or on windows to download. I don't think Outlook is involved here; I don't use it.
Are you running a 64bit version of Win7?
As reported many, many times in this forum, there are no USB drivers for this version.
Please read the Sticky post at the top of this section for guidance:
http://forums.palm.com/t5/Windows-HotSync/Windows-7-and-Vista-hotsync-instructions-here/td-p/251755/...
WyreNut
I am a Volunteer here, not employed by HP.
You too can become an HP Expert! Details HERE!
If my post has helped you, click the Kudos Thumbs up!
If it solved your issue, Click the "Accept as Solution" button so others can benefit from the question you asked!

Synchronize two counter outputs on 6071E card

Well, it's the usual how do I synchronize two counters problem.
I'm using the 6071E with DAQmx .NET 4.0. I define a Task and attach to it two counter output channels with implicit timing and zero initial delay . When running the program
I catch the first edge with a scope single trigger. There is always a delay between the first edge of ctr0 and the first edge of ctr1 of 16.3 microsecs. Is there a way, besides setting the initial delay of ctr0 to 16.3 microsecs, to make the counters to always start together? what is the source of the delay(software/hardware) and should it always stay constant.
any help is welcome
Solved!
Go to Solution.

The source of the delay is that despite being in the same tasks the counters are still started sequentially by software. I'm surprised the delay you are seeing is constant.
If you want the counters to start together you should configure a start trigger. Once you start the counter tasks in software, issue the start trigger to begin generating your output pulses. The start trigger must be a hardware signal--as an example you might configure a software-timed digital output and wire it back in to one of the PFI lines.
If you want to avoid any additional wiring, you could split the counters into two separate tasks. Trigger one counter with the internal output of the other (start the task that is going to be triggered first). Doing this instead of using an external trigger, I would expect an additional delay between the counters on the order of 100 ns as the initial delay is at minimum 2 timebase ticks.
Best Regards,
John Passiak

Counter to measure frequency with multiple channels (Analog In/Out) in one vi

Hi,
I am using DAQ 6062E. I have multiple channels: an Analog In, Analog Out, Count Edges, and Count Frequencies. Without Count Frequency, the program works fine, I have defined a Sample Clock for each channel and then a common sampling rate. When I add Count frequency channel, I am not able anymore to use Sample Clock, since I get an error that Sample Clock can not be used, and if I change the Sample clock of the Count frequency to Implicit, then I can not connect different channels with a same sampling rate. In the attached file, if the Count Frequency is not connected to any Sample clock and sampling rate, the program works, but now I can not run the program for more than 5-10 Hz sampling rate, otherwise I get the error: 209802 “occurred at DAQmx wait for next sample clock, slow down the sample clock”. Does anybody know how to fix this problem?
Thanks a lot,
Azadeh
Attachments:
multiple channel.jpg ‏117 KB

Hi Otis,
Thanks for looking at the problem. I ran just two counters in a same vi. I was not able to use the Sample Clock since I needed to define an external sample clock source. The vi is attached. I could run this vi fast (200Hz). So, I am not sure why when two counters are combined with AI/AO the rate is very slow. I have attached three vi(s). Just two counters, AI/AO/1 counter, and AI/AO/2 Counters vis. I am able to run the vis in 200 Hz except the vi with AI/AO/2 counters (maximum sampling rate 20Hz). I appreciate if you can look at it if I am missing something.
Thanks,
Azadeh
Attachments:
AI_AO_2 Counter.vi ‏153 KB
2 Counter.vi ‏61 KB
AI_AO_1 counter.vi ‏138 KB

How to count frequency of two signal at the same time ?

Hello every one
please help me with this one i am really stuck.
The situation   : I have two square wave signal, and i want to measure the frequency of both of themat the same time.
the problem : Error -50103 occurred at DAQmx Read (Counter DBL 1Chan 1Samp).vi:3
Please see the attachement.
i also have 3 analog inputs to be measured.
but i dont have any problem with the analog inputs,,,multiple analog inputs can easily be measured,,,,,but the prob lem is in the digitl (square wave ) signals.
Attachments:
i want to use two counter input.GIF ‏54 KB
two counter tasks1.vi ‏250 KB

NI has an excellent overview of the accuracy and tradeoffs of the different freq measurement methods titled "Making Accurate Frequency Measurements." To boil down the essence of it, the (possibly) increased accuracy of the 2-counter method depends on a relatively long collection / accumulation time which would in turn typically limit the rate at which you could update your measured freq value.
Now let me offer some friendly but blunt advice. LabVIEW makes it easy to collect data. However, there are many other factors affecting the usefulness of that data. I support the dictum: "It is hard to measure *well*."  Choice of sensors, their sensitivity to environment, various sources of noise, an understanding of the decision to be made from the data, programming methods, etc. And even more etc.
What I mean is that just because a hardware freq measurement can be performed that is precise to 1 part per million, it would be very RARE in a test that ALL of those 6 significant digits prove useful. In your app, the measurements are presently only approximately correlated in time. And the gap of blind time between measurements will usually represent a much longer period of time than the measurement itself.
Analogy: suppose you had a 100 minute film at 25 frames/sec for a total of 150_000 frames. Now start selecting individual frames that are separated by some random # of frames between about 200 and 500. In the end, you may end up with a sequence of 400 frames in the correct order. Each individual frame is VERY accurate, but the collection of all of them can zip by in 16 seconds and not give you a much understanding about the movie.
What would usually work out much better is to sacrifice some accuracy in order to collect a greater quantity of frames. You trade off the instantaneous accuracy for the overall coherency.
Sorry, got on a roll...   Back to your question. My own preference is almost always to avoid consuming hardware resources when not truly necessary. I've been toying with counters for many years and have still never once deployed an app using a 2-counter frequency measurement. I do the 1-counter measurement and save the other counter(s) for other purposes.
If you've got an M-series board, the 80 MHz timebase allows you to measure a 500 kHz pulsetrain with a quantization error of only about 0.06% (1 part in 160). There's a pretty fair chance that whatever physical process emits that pulsetrain isn't appreciably more stable than that
-Kevin P.

How do I use a counter to measure frequency and multiple analog signals in the same VI?

I have a PCI-6071E, an SC-2345 with multiple modules, and a PXI-8184 (with a PXI-1002 Chassis).
My goal is to monitor pressures, flows, temperatures, and speed in one VI.
I am using Measurement and Automation Explorer version 3.1.1.3004 to manage my channels.
My speed is a PWM signal which I recently rewired through the counter 0 of my board.
I was hoping to configure this to read frequency directly in measurment
and automation, have this scale the value to RPM, and then feed it
directly in to my labView program.
In labView, it will not except this signal though.
I get error -200300 from the DAQmx Start Task.vi
Possible reasons(s):
Invalid timing type for this channel.
Property: SampTimingType
You Have Requested: Sample Clock
You Can Select: Implicit, On Demand
After doing some research, it seems that the counter wants "Implicit"
selected for the DAQmx Start Task.vi, but then I cannot use my other
channels. Also, counter is included in the "Sample Clock" option
description, so I do not understand why it is not working.
Does anyone know how to work around this problem or a way to configure the counter so that it will work in this way?
All my other channels are Analog.
Thank you.

I am working on getting just the counter working by using
the program posted previously, and I am running into issues. Periodically I get
the error:
Error -200141
occurred at DAQmx Read (Counter DBL 1Chan 1Samp).vi
Possible reason(s):
Data was overwritten
before it could be read by the system.
If Data Transfer
Mechanism is Interrupts, try using DMA. Otherwise, divide the input signal
before taking the measurement.
It seems to work better if I use cascaded counters, but I need timer 0 for
analog channels when I run this code along with the program for the other
measurements.
I have tried averaging, and selecting different values for the millisecond
timer, and these did not seem to have an effect.
I tried different DAQms configurations and "Counter DBL 1Samp" seemed
to work the best.
The program will work for a while and then it will give me the above error
message.
If I use counter 0 as a cascaded counter input, the program runs fine. If I run
this with other analog channels, it errors out because the analog channels use
counter 0.
If I use counter 1 as a cascaded counter input, it seems to work better than a
single channel, but it will still error out with the above error.
If I use only counter 1, I get the error above even faster.
Also, none of the
configurations give measurements outside the While Loop.
The only place I can add a speed dial for the front panel is within the While
Loop.
Is there someway to get the signal to continuously send out of the while loop?
I thought if I could get the signal out of the while loop, I could condition it
anyway I wanted without the program erroring out.
Any suggestions would be much appreciated.
Thank you.
Attachments:
Counter_error.jpg ‏45 KB

Two Counter channels in one task ID with DAQmx?

I am writing a program which will control the movement of a gimble on the X and Y axis with servo motors while recieving
position feed back from two encoders on those axis. I am using a 6251M series card's AO to control the movement
of the gimble, while running the encoders into a 6602 for position. When setting up my task ID in MAX I noticed I could add
both ctr0 and ctr1 to the task ID, but when I tried read the counters with that task I got an error in Labview and with the
test function in MAX saying I need to use a multichannel read. I can not find a multichannel read under the counter
section of my DAQmx read, and was wondering if this is even possible. I am used to programming with Traditional DAQ
and know you have to keep separate counter task ID's, but having bought an M series card and having to use DAQmx I
was wanting to know if I could combine them.
Thanks

You can have multiple channels in a single task, but those channels all
have to be of the same type. You can have analog inputs together
with other analog inputs, but cannot combine digital inputs/outputs,
analog outputs or counter tasks with that analog input task.
Once you pair only like tasks together then you shouldn't run into any more issues like this.
Best of luck,
Otis
Training and Certification
Product Support Engineer
National Instruments

Counting rows with multiple criteria

I know this is a silly beginner question, but is there an easy way to count the number of rows in a table which match criteria based on different columns (sort of a countif with multiple criteria). For example, if Column A in a table has "All, Some, None" responses and Column B has "Main, Off" responses, is there an easy way to count the number of rows in which Column A has All and Column B has Off?

Neondiet wrote:
From an intellectual and philosophical view I agree with you. But from a practical view what I really want to do is just use one application for my spreadsheet tasks, not jump back and forth because one sheet I share with MS Windows users, and another with Numbers users, and another with OS X users who don't have Numbers or Excel but do have NeoOffice. Maybe I have to settle for that though.
Yeah... this kind of situation stinks. Its like needing to writing software that will run on both Macs and PCs.
Anyway, I've followed the advise in this forum and resorted to using a hidden column with concatenated values to solve my own problem, though it does seem like a bit of a hack compared to managing a single formula in a single cell. Horses for courses I suppose.
jaxjason has posted a very elegant pivot table like solution that utilizes this technique. See http://www.numberstemplates.com/forums/showthread.php?t=36
Btw, from what I've read on the net to date, SUM (in Excel) with an array formula answers the original authors problem of counting occurrences of values, not SUMPRODUCT; which I believe sums up the contents of cells in a range, if cells in other ranges match specific criteria.
Yes, if you use the '*' (as indicated above) then SUM() is sufficient though SUMPRODUCT() will work as it degenerates to SUM when there is only one argument. If you use two arrays as arguments (like: = SUMPRODUCT((A1:A4="All"), (B1:B4="Off")), then SUMPRODUCT() is necessary. Here's my understanding of how it works (I hope your able to follow my abuse of algebraic techniques):
=SUM((A1:A4="All") * (B1:B4="Off"))
expanding the array expressions...
=SUM((A1="All", A2="All", A3="All", A4="All") * (B1="Off", B2="Off", B3="Off", B4="Off"))
at this point Excel computes the equality expressions, for example...
=SUM((TRUE, FALSE, TRUE, FALSE) * (TRUE, TRUE, FALSE, FALSE))
expanding the array multiplication...
=SUM((TRUE * TRUE, FALSE * TRUE, TRUE * FALSE, FALSE * FALSE))
Excel, apparently, then, when forced to multiply Boolean values, maps TRUE -> 1 and FALSE -> 0...
=SUM((1 * 1, 0 * 1, 1 * 0, 0 * 0))
performing the multiplications...
=SUM((1, 0, 0, 0))
summing...
=1 + 0 + 0 + 0
resulting...
=1
I'm afraid, now, if I continue any further, Yvan will chastise me.

Tool for synchronizing multiple Palm Desktops across a network

Hello, I'm new to this site but it seems as though if there's an answer to my question it's here so I'm diving right in.
I have my handheld set up to synchronize with multiple computers. I have a home desktop, work desktop, and laptop, each of which has Palm Desktop installed and knows how to sync with my handheld. Syncing any one of the PD installations is easy -- I've been able to get it to work over a variety of methods and am very happy with that.
The problem is that if (as happens frequently) I make some changes to the data on my laptop, then later some changes on my desktop, and then finally some other changes on my handheld, the only way to get all the systems in sync again is a series of hotsync operations driven by the handheld. (Three in that case.)
What I'd like to be able to do is synchronize the two PCs directly, so that I only need the handheld to be involved in the process once. I know there are tools to get PD to sync with other software like Outlook. Are there any that sync PD with PD?
Thanks for your help!
Post relates to: Treo 755p (Sprint)

Hello fruitbat and welcome to the Palm forums.
As far as I know, there are no tools from Palm or any third-parties that will sync the Palm Desktop PIM databases between two computers without the handheld being involved. Palm OS 5, Palm Desktop, and the HotSync Manager, where never intended to be network applications.
Alan G
Post relates to: Treo 755p (Sprint)

Two counter inputs and counter output NI 9401

I am trying to configure two counter inputs and one counter output on one NI 9401. I have looked and found how to configure digital lines in booth directions but it seems like I can only do two counters in all on one module. Can someone verify this for me or let me know how to get all three on to one module?
Thank you

Hi mschoenwald,
The counters are actually located on the backplane of whatever chassis you are using--I'll assume you are using cDAQ and not cRIO.
If you have the older <link no longer exists>, then there are only 2 counters available in general. You can access both from a single parallel (8 lines or less) digital module in slot 5 or 6 of the chassis.
The 2nd generation Compact DAQ chassis (including 9174, 9178, 9181, 9188, etc.) includes 4 counters. You may access them from any slot with a parallel module. There is no restriction preventing you from accessing all 4 simultaneously from a single module.
The 9401 is bi-directional and configurable by nibble (line0:3 may be configured one direction, and line4:7 another). However, it is quirky in that it requires the line direction to be configured before any of the tasks are started. This is because the data lines themselves are used to set the line direction behind the scenes. The best way to work around the behavior is to use DAQmx Control Task to explicitly reserve your tasks before any of them are started (see here). Keep in mind that the counter output should use the opposite nibble from the two counter input tasks.
Best Regards,
John Passiak

Synchroniz​ing two counter frequency inputs with multiple analog inputs

Similar Messages

Maybe you are looking for

Synchronizing two counter frequency inputs with multiple analog inputs