To multiplicate frequency with one counter

Hello,
To start I'm french.
I wish to multiply the frequency of a signal PWM.
If possible with only one counter.
Thank you !!!!

Bonjour,
Pouvez vous préciser quelque peu votre requête... Quel environnement de prgrammation (Labview?)
Quelle carte utilisez vous?
Pourquoi la multiplication avec seulement un compteur?
Merci d'avance
David D.
Ingénieur d'Applications
NI France

Similar Messages

Generate two alternating PWMs with one counter of 6025E

I am using LabView 6.0.2 with a PCI-6025E card. My requirement are to put out a pwm signal with 250Hz. The problem is, that for example, first a PWM with exact 100 pulses of duty cycle 1% is needed, after that exact 5 pulses of 10% duty cycle. These two PWMs are repetetive without any big pauses between. I tried this with Pulse Train Generation with "Changing Pulse Specs.llb" from the ni libraries, but the PC based on windows is not able, to do the PWM changes in these exact time slots. Note: The second timer of the card is used for another item.

Unfortunately, you won't be able to do exactly what you want with a single counter. You'll need to use additional hardware. Here are some possibilities:
1. Analog Output:
A 1% duty cycle at 250 Hz requires a minimum of 25 kHz update rate, but your 6025E only goes up to 10 kHz. Your board is also limited by having only 1 DMA channel for Data acq buffered operations, and it may already by used by your other counter's operation.
If you had an analog board with faster output, you could try to create a buffer with 0 V and 5 V values representing the desired finite pulse train. However, if the device you're controlling with PWM requires TTL edges, the rise and fall times of your DAC output may still not be fast enough to fool it.
2.
PCI-6601/6602 Counter/Timer:
You could use two counters from a 6601 to generate the finite pulse trains you describe, but there would need to be a pause between the the two duty cycles. The pause is where your software detects the end of one finite pulse train and reprograms the counters to generate the other one. The pause might likely vary from 10 to 100 or more msec.
If that variable dead time between pause trains is acceptable, the 6601 is the cheapest solution I know of for today's application. If you need reuse for future apps, you might want to consider the 6602 for double the price, but a bit more than double the capability.
3. PCI-6533/6534:
NI's timed digital boards would allow you to define the pulse trains as a one-bit digital pattern that you could generate continuously. I suspect the 6533 would suffice for the app you describe.
Please double-check these hw suggestions with your local rep before ordering. (S)he'll know more than me about
your present-day app and potential future needs. Good luck!
-Kevin P.

Measure pulse frequency with 4.7 volt peak amplitude

used two shipped Measurment Studio Vb.Net 2005 Examples:
1-Example 1 : CountDigEvents "MEASURES PULSE COUNTS" and Example 2: MeasDigFrequency_LowFreq1Ctr "MEASURES PULSE FREQUENCY"
2-Example 1 works fine measuring pulse counts , however Example 2 did not recognize pulse frequency , the pulse amplitude voltage is 4.7 volt peak
3-during testing used counter ch0 channle by connecting Sorce0 and Dgnd pins to signal source.
4-using Nidaqmx 9 and MIO-16xe-10 daq
5-pulse frequency around 10 khz
QUESTION:
-please advice what to do to make frequency measures ?
Thanks

Hi MyKat,
Note that the connections are different for edge counting and low frequency frequency measurements with one counter. For the latter, you'll need to connect the signal to PFI 9 rather than PFI8 as you did for edge counting.
http://zone.ni.com/reference/en-XX/help/370466W-01/mxdevconsid/eseriessigcounters/
Regards,
-Jim B
Applications Engineer, National Instruments
CLD, CTD

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 generate a delayed retriggerable pulse using only one counter with PXI 6070E card

Hi
I have a problem in generating a retriggerable delayed pulse with a single counter(triggered through a signal at gate) using PXI 6070E card. VI was developed in NI LabVIEW traditional DAQ Ver.7.1. I have used the "delayed pulse generator config" VI and a "Start counter" & "Stop counter" VIs for the purpose. But there is no output seen at the out terminal of counter. So I introduced a "wait" VI and set it to 1 sec. Now the pulse output appears but some pulses are missing mometarily after every 1 sec interval. (any solution for this)
I have gone through a few similar requests in the forum but they suggest either to use two counters or to generate a finite pulse train which does'nt fit my application. Moreover PXI 6070E has only 2 counter timers. I am already using one counter to measure the frequency of a pulse train(signal 1). The application requires to generate a delayed retriggerable pulse for every pulse in signal 1. So I have only one counter left.
Can I measure the frequency of signal 1 by analog means.? so that I can use two counters for pulse generation. (Signal 1 is a TTL signal).
Request some help.
Thanks in Advance
Regards

A finite pulse train (N_Pulses >= 2) does require the use of 2 counters on most of our older hardware including your 6070E. If you're just talking about generating a single retriggerable pulse, you would only need one counter.
Here's an example in Traditional DAQ that shows you how to set a retriggerable pulse generation (it also allows you to adjust the characteristics of the pulse on-the-fly).
If you're writing a new program, you might consider switching to DAQmx as it supports NI's latest hardware and recent OSes should you ever need to upgrade. Traditional NI DAQ is no longer in active development. Here's an example of how to implement a retriggerable pulse generation in DAQmx. You should take note that you can't use the two drivers to simultaneously talk to the same piece of hardware, although you should be able to go back and forth by resetting the Traditional DAQ driver before switching to DAQmx.
Best Regards,
John Passiak

Counting (interneal timebase)events with only one counter

Hello,
i am using a PXI-6115 card. This card is external clocked with 8 MHz. But I want to measure only about every second. So I divided the external clock with the internal counter 0. This works fine.
Now my problem. Now I want to know the external clock rate. Is it possible to build a pulse period measurement with only one counter??
I thinking of counting internal timebase- pulses with counter 1 and to start and stop the counter 1 by the output of counter 0.
Is this possible and how??
Thanks for help, Ruediger

Yes, there's a way to measure pulse periods with a single counter. The trick is to perform a buffered period measurement and sum the periods. The size of the buffer will determine the quantization/roundoff error.
The source of this error is that you have no control over the initial phase relationship of your external clock and your internal timebase. There's a nominal ratio between the two frequencies, and you'd start by expecting ratio * (buffer size) total cycles counted.
However, your actual count must be an integer, so you'll get either the next-highest or next-lowest integer, but you can't predict or control which one.
Example: If you collect 1 period at 8 MHz using the internal 20 MHz timebase, you'll capture either 2 or 3 e
dges from your timebase, implying a measured frequency of either 10 MHz or 6.6667 MHz.
If you collect 1001 periods, you'll capture a total of 2502 or 2503 timebase edges, implying a measured frequency of either 8.0016 MHz or 7.9984 MHz.
Notes:
1. In many cases, you can set up for buffered event counting, using the internal 20 MHz clock as a source and your external 8 MHz as a gate.
The advantage is that the buffered values already represent cumulative time so you don't need to sum them.
A disadvantage would be that the internal 24-bit counter value will roll-over in less than 1 second at 20 MHz. I typically capture periods and then sum in software because I can convert to floating point between capture and sum if necessary to produce both high-resolution and long duration measurements.
2. You should typically ignore the very first value in the buffer and work only with the others. If you want to capture 1001 legitimate periods, size the buffer for at least 1002
-Kevin P.

Performance problem with more than one COUNT(DISTINCT ...) in a query

Hi,
(I hope this is the good forum).
In the following query, I have 2 Count Distinct on 2 different fields of the same table. Execution time is okay (2 s) with one or the other COUNT(DISCTINCT ...) in the SELECT clause, but is not tolerable (12 s) with both together in the query! I have
a similar case with 3 counts: 4 s each, 36 s when together!
I've looked at the execution plan, and it seems that with two count distinct, SQL server sorts the table twice before joining the results.
I do not have much experience with SQL server optimization, and I don't know what to improve and how. The SQL is generated by Business Objects, I have few possibilities to tune it. The most direct way would be to execute 2 different queries, but I'd like
to avoid it.
Any advice?
SELECT
DIM_MOIS.DATE_DEBUT_MOIS,
DIM_MOIS.NUM_ANNEE_MOIS,
DIM_DEMANDE_SCD.CAT_DEMANDE,
DIM_APPLICATION.LIB_APPLICATION,
DIM_DEMANDE_SCD.CAT_DEMANDE ,
count(distinct FAITS_DEMANDE.NB_DEMANDE_FLUX),
count(distinct FAITS_DEMANDE.NB_DEMANDE_RESOL_NIV1)
FROM
ALIM_SID.DIM_MOIS INNER JOIN ALIM_SID.DIM_JOUR ON (DIM_JOUR.SEQ_MOIS=DIM_MOIS.SEQ_MOIS)
   INNER JOIN ALIM_SID.FAITS_DEMANDE ON (FAITS_DEMANDE.SEQ_JOUR=DIM_JOUR.SEQ_JOUR)
   INNER JOIN ALIM_SID.DIM_APPLICATION ON (FAITS_DEMANDE.SEQ_APPLICATION=DIM_APPLICATION.SEQ_APPLICATION)
   INNER JOIN ALIM_SID.DIM_DEMANDE_SCD ON (FAITS_DEMANDE.SEQ_DEMANDE_SCD=DIM_DEMANDE_SCD.SEQ_DEMANDE_SCD)
WHERE
( ( DIM_MOIS.NUM_ANNEE_MOIS ) >201301
GROUP BY
DIM_MOIS.DATE_DEBUT_MOIS,
DIM_MOIS.NUM_ANNEE_MOIS,
DIM_DEMANDE_SCD.CAT_DEMANDE,
DIM_APPLICATION.LIB_APPLICATION

Here is the script, nothing original. Hope this helps.
-- Fact table :
-- foreign keys begin by FK_,
-- measures to counted (COUNT DISTINCT) begin with NB_
CREATE TABLE [ALIM_SID].[FAITS_DEMANDE](
   [SEQ_JOUR] [int] NOT NULL,
   [SEQ_DEMANDE] [int] NOT NULL,
   [SEQ_DEMANDE_SCD] [int] NOT NULL,
   [SEQ_APPLICATION] [int] NOT NULL,
   [SEQ_INTERVENANT] [int] NOT NULL,
   [SEQ_SERVICE_RESPONSABLE] [int] NOT NULL,
   [NB_DEMANDE_FLUX] [int] NULL,
   [NB_DEMANDE_STOCK] [int] NULL,
   [NB_DEMANDE_RESOLUE] [int] NULL,
   [NB_DEMANDE_LIVREE] [int] NULL,
   [NB_DEMANDE_MEP] [int] NULL,
   [NB_DEMANDE_RESOL_NIV1] [int] NULL,
CONSTRAINT [PK_FAITS_DEMANDE] PRIMARY KEY CLUSTERED
   [SEQ_JOUR] ASC,
   [SEQ_DEMANDE] ASC,
   [SEQ_DEMANDE_SCD] ASC,
   [SEQ_APPLICATION] ASC,
   [SEQ_INTERVENANT] ASC,
   [SEQ_SERVICE_RESPONSABLE] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
CONSTRAINT [AK_AK_FAITS_DEMANDE_FAITS_DE] UNIQUE NONCLUSTERED
   [SEQ_JOUR] ASC,
   [SEQ_DEMANDE] ASC,
   [SEQ_DEMANDE_SCD] ASC,
   [SEQ_APPLICATION] ASC,
   [SEQ_INTERVENANT] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] WITH CHECK ADD CONSTRAINT [FK_FAITS_DEMANDE_DIM_APPLICATION] FOREIGN KEY([SEQ_APPLICATION])
REFERENCES [ALIM_SID].[DIM_APPLICATION] ([SEQ_APPLICATION])
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] CHECK CONSTRAINT [FK_FAITS_DEMANDE_DIM_APPLICATION]
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] WITH CHECK ADD CONSTRAINT [FK_FAITS_DEMANDE_DIM_DEMANDE] FOREIGN KEY([SEQ_DEMANDE])
REFERENCES [ALIM_SID].[DIM_DEMANDE] ([SEQ_DEMANDE])
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] CHECK CONSTRAINT [FK_FAITS_DEMANDE_DIM_DEMANDE]
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] WITH CHECK ADD CONSTRAINT [FK_FAITS_DEMANDE_DIM_DEMANDE_SCD] FOREIGN KEY([SEQ_DEMANDE_SCD])
REFERENCES [ALIM_SID].[DIM_DEMANDE_SCD] ([SEQ_DEMANDE_SCD])
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] CHECK CONSTRAINT [FK_FAITS_DEMANDE_DIM_DEMANDE_SCD]
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] WITH CHECK ADD CONSTRAINT [FK_FAITS_DEMANDE_DIM_INTERVENANT] FOREIGN KEY([SEQ_INTERVENANT])
REFERENCES [ALIM_SID].[DIM_INTERVENANT] ([SEQ_INTERVENANT])
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] CHECK CONSTRAINT [FK_FAITS_DEMANDE_DIM_INTERVENANT]
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] WITH CHECK ADD CONSTRAINT [FK_FAITS_DEMANDE_DIM_JOUR] FOREIGN KEY([SEQ_JOUR])
REFERENCES [ALIM_SID].[DIM_JOUR] ([SEQ_JOUR])
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] CHECK CONSTRAINT [FK_FAITS_DEMANDE_DIM_JOUR]
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] WITH CHECK ADD CONSTRAINT [FK_FAITS_DEMANDE_DIM_SERVICE_RESPONSABLE] FOREIGN KEY([SEQ_SERVICE_RESPONSABLE])
REFERENCES [ALIM_SID].[DIM_SERVICE] ([SEQ_SERVICE])
GO
ALTER TABLE [ALIM_SID].[FAITS_DEMANDE] CHECK CONSTRAINT [FK_FAITS_DEMANDE_DIM_SERVICE_RESPONSABLE]
GO
-- not shown : extended properties
-- One of the dimension tables (they all have a primary key named SEQ_)
CREATE TABLE [ALIM_SID].[DIM_JOUR](
   [SEQ_JOUR] [int] IDENTITY(1,1) NOT NULL,
   [SEQ_ANNEE] [int] NOT NULL,
   [SEQ_MOIS] [int] NOT NULL,
   [DATE_JOUR] [date] NULL,
   [CODE_ANNEE] [varchar](25) NULL,
   [CODE_MOIS] [varchar](25) NULL,
   [CODE_SEMAINE_ISO] [varchar](25) NULL,
   [CODE_JOUR_ANNEE] [varchar](25) NULL,
   [CODE_ANNEE_JOUR] [varchar](25) NULL,
   [LIB_JOUR] [varchar](25) NULL,
   [LIB_JOUR_COURT] [varchar](25) NULL,
   [JOUR_OUVRE] [tinyint] NULL,
   [JOUR_CHOME] [tinyint] NULL,
CONSTRAINT [PK_DIM_JOUR] PRIMARY KEY CLUSTERED
   [SEQ_JOUR] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
GO
ALTER TABLE [ALIM_SID].[DIM_JOUR] WITH CHECK ADD CONSTRAINT [FK_DIM_JOUR_DIM_ANNEE] FOREIGN KEY([SEQ_ANNEE])
REFERENCES [ALIM_SID].[DIM_ANNEE] ([SEQ_ANNEE])
GO
ALTER TABLE [ALIM_SID].[DIM_JOUR] CHECK CONSTRAINT [FK_DIM_JOUR_DIM_ANNEE]
GO
ALTER TABLE [ALIM_SID].[DIM_JOUR] WITH CHECK ADD CONSTRAINT [FK_DIM_JOUR_DIM_MOIS] FOREIGN KEY([SEQ_MOIS])
REFERENCES [ALIM_SID].[DIM_MOIS] ([SEQ_MOIS])
GO
ALTER TABLE [ALIM_SID].[DIM_JOUR] CHECK CONSTRAINT [FK_DIM_JOUR_DIM_MOIS]
GO

Measuring frequency with counter or analog input?

I have some frequencies which I need to measure. Some signals are digital and some are analog.
I have a PXI-6040E DAQ which has both counters and analog inputs.
I heard that you can measure higher frequencies with the counters than with analog inputs.
What is the range of frequencies an analog input can determine versus a digital counter?
Where is the cutoff that you must absolutely use a digital counter to determine the frequency?
Is the cutoff different for different DAQ cards? Or is generally the same.

Have you looked at the specs for the device? The max sample rate and the max counter input will be listed there. The max frequency for an analog input is based on nyquist sampling theory. Are you at all familiar with? It states your sampling frequency has to be at least twice the frequency you are measuring.
Since each device might have a different max sample rate, your last question is answered.

Using one counter with FiniteSamps and another with ContSamps

I am trying to use 2 counters on the USB-6229 (or USB-6259), where one counter is set up for FiniteSamps and another for ContSamps. I have the following MeasurementStudio code:
ErrChk DAQmxCreateCOPulseChanTicks(hCnt0, "Dev1/ctr0", "", "20MHzTimebase", DAQmx_Val_Low, 0, 400, 400);
ErrChk DAQmxCfgImplicitTiming(hCnt0, DAQmx_Val_FiniteSamps, 100);
ErrChk DAQmxStartTask(hCnt0);
ErrChk DAQmxCreateCOPulseChanTicks(hCnt1, "Dev1/ctr1", "", "20MHzTimebase", DAQmx_Val_Low, 0, 400, 400);
ErrChk DAQmxCfgImplicitTiming(hCnt1, DAQmx_Val_ContSamps, 2);
ErrChk DAQmxStartTask(hCnt1);
When I run it, I get a run-error 50103 "The specified resource is reserved". If I change the FiniteSamps to ContSamps on the first counter, everything works fine.
If I use only one counter with FiniteSamps, everything also works fine.
Is this a bug in DAQmx or the dual counter use on M-series devices is limited to ContSamps?
Vic
Solved!
Go to Solution.

Hi Vic,
This is actually expected on an M Series device. Here's a timing diagram from the M Series User Manual that might make this a bit more clear:
The device actually uses one counter to gate the other so the result is a finite pulse generation. If you can provide the gate from another source, you may configure a continuous pulse generation on both counters and gate them (DAQmx calls this a "Pause Trigger") from this external signal.
You might also want to look into using Correlated Digital I/O to generate multiple finite pulses (up to 32 lines on your 6229 and 6259). You could use one of the counters to generate a timebase for the digital lines, and build the waveform accordingly.
One thing to note is that our new X Series boards can generate a finite pulse generation on a "single" counter (there is actually a paired internal counter that allows for this). There are four user-accessible counters on X Series devices, meaning you could generate four finite pulse trains.
Best Regards,
John
John Passiak

2 Square signal to frequency with DAQCard ?

Hello,
My configuration : PC portable P4 / 1.8GHz, Win 2000, Labview 7.0, DAQCard AI-16E-4, BNC 2110 and two magnetic speed sensors (6000rpm, 120 top/rotary)
1) I would like to recorde the two frequencies with the two counters of the DAQCard. Can I do it with my configuration (2 counters are enough ?) ?
2) Can I synchronize these two inputs with analog inputs ? If not, which configuration I need for ?
Thanks a lot,
Yvan

You can make a frequency measure with only one counter. This method use
the internal timebase as source and your input signal as gate: the
process take the number of clock period in a period of your input to
compute it's frequency.
Accuracy of this method is quite good if the input frequency is small
compare to the internal timebase. So with the sensor you described:
   6000rpm => 100 rotary per second
   with 120 top per rotary => 12000 top per second
The AI-16E-4 use a 20MH internal timebase, so I think there is no problem
More information about frequency measurement...
For the synchornisation, I'm not sure to clearly understand what you
need, but take a look to the DAQmx timming and DAQmx start trigger VIs.
.mrLeft{float:left} .mrInfo{border-left:solid 1px #989898;font-size:x-small;color:#989898}
Mathieu R.
  CTD - Certified TestStand Developer / Développeur TestStand Certifié
  CLAD - Certified LabVIEW Associate Developer

Buffered Edge Counting 20 MHz with duplicate count prevention

Dear all,
I went through the specs of several boards (M- series, S- and E- series, 6602 etc...). It seems that these boards can count edges with duplicate count prevention on at a maximum rate <= 20 MHz (i.e., 1/4 of 80 MHz) - but maybe I have misunderstood the docs.
Is there a NI board capable of buffered edge counting with a general purpose counter for random events going at rates from 0 Hz to > 20 MHz? Do I need to look for a reconfigurable board?
Thanks in advance.

Dear Elizabeth,
Thanks for the answer.
In my application, events arrive asynchronously (actually, randomly). During the duration of a gate (namely, 1 microsecond), one expects anything from 0 to many (i.e., possibly more than 20, up to 80) events. This requires duplicate count prevention.
I may have misunderstood the specs for M series boards, but the document:
Using Duplicate Count Prevention for Counter Tasks in NI-DAQmx
from the NI web site, for instance, states that:
"All the other timebase edges that occur while the external source input is high are ignored. If no source edges are detected between two gate edges, as shown in Figure 3, duplicate count prevention ensures that pulse measurements return zero because the external source must be logic high to allow the internal timebase to increment the count register. This reduces your maximum source frequency to quarter of the original maximum (80MHz) timebase for NI-STC II and NI-TIO boards. Therefore duplicate count prevention should only be used if the frequency of the Source signal is 20 MHz or less.
Duplicate count prevention should only be use in the following situations:
Counter measurements
The counter Source is using an external signal (such as PFI x)
The frequency of the external source is 20 MHz or less
What's your take on that?
Thanks for your time.

Can source and gate used to measure 2 signals using one counter?

I have one PCI 6602 card to measure measure the frequency. PCI 6602 has 10 channels, in which channel 5 and 10 doesn't have 'source' terminal.
We have to measure frequency from 16 signals using one PCI 6602.
From channel 1 to 4 and 6 to 9, we have 8 'Gate' and 8 'Source' terminals.
We have connected 16 signals to these 16 terminals.
At any given point of the time we want to measure either 'Gate' signals(8) or 'Source' signals(8).
Can any provide any guidance to make a program in labview to measure frequency (period) as per above given points?
Regards
Vijay

Hello Vijay,
It takes one counter for each digital frequency you want to measure and the PCI-6602 has 8 counters total. This means that the maximum number of digital frequencies you can measure is 8. If you want to measure 16 frequencies you'll need 16 counters.
Single counter frequency measurements are made by comparing the board's time base (80 MHz) to an external frequency. The board counts the number of time base periods that occur during one period of your incoming frequency. When you configure the board to take a single counter frequency measurement the card routes the time base to the source of the counter and then you connect the frequency you want to measure to the gate of the counter.
Here are a couple of articles that explain how these measurements are taken and calculated. (The second article is on period measurements so for frequency measurements you measure period and take the inverse):
Making Accurate Frequency Measurements
Period Measurements with a Counter
There are example programs available in the LabVIEW example finder. You can locate these by going to Help>> Find Examples... The examples you want is: Hardware Input and Output>> DAQmx>> Counter Measurements>> Digital Frequency>> Measure Digital Frequency- Low Freq 1 Ctr.vi.
I hope this explains how counters work and why you need one counter per measurement.
Cheers,
Brooks

Low Frequency Measurements using counter timers

I am trying to measure multiple speeds using FP-CTR-502 modules. I am having a resolution problem. Looking at the post at the following URL (http://forums.ni.com/ni/board/message?board.id=110&message.id=3601&query.id=42252#M3601) looks like exactly what I need to do, but I'm not sure how to program this. Does anyone have any example code to get me headed in the right direction?

Hi Tcrower,
Here is the example that Carl L. was describing in his forum post along with his instructions. Also, there are thorough instructions for using the program in the front panel as well as in File >> VI Properties >> Documentation.
You can measure frequency in two ways using a counter.
1) Measure the time it takes for a set number of pulses to pass or,
2) Count the number of pulses that pass in a set amount of time.
For low-frequency signals it is best to measure the time duration of a set number of pulses. If we tried to calculate the number of pulses that passed in a set amount of time, we would need a long gate period to get accurate results.
The drawback of measuring the amount of time it takes for a set number of pulses to pass is that the sample period varies with the frequency of the signal.
To accurately measure low frequencies with a CTR module, select two counter channels, one output channel, and one gate input channel. Count Input 0 counts the pulses of the signal that we are measuring. The output of the counter is set to high for x pulses and low for x pulses, which is used as the gate of Count Input 1. The source of Count Input 1 is the internal clock reference (the example can be modified to use an external clock reference). During the high phase of Count Input 0, Count Input 1 counts the pulses of the clock reference.
During the low phase, we read channel 1 and reset the counter.
For example, if the output of Count Input 0 is set to high for 4 pulses and the signal has a frequency of 20 Hz, the output of Count Input 0 is high for 200 ms. During the high phase, we will count 200 counts if we are using the 1 kHz internal clock reference. So to calculate the frequency, we have F = #pulses/duration = timebase * terminal count/counts = 1000 Hz * 4 terminal counts/200 counts = 20 Hz.
Regards,
Hal L.
Attachments:
Low_Frequency_Measurement_(CTR).zip ‏77 KB

Showing Duplicate records in a report with the count of their occurrence

Hi Members,
I am novice to BI. i need your suggestion to achiever one of the functionality. A report is required to be built with columns Incident ID, Task ID, Task Name. The Original report is below:-
In the above report I have to display only duplicated records once. Distincat records are not required to be shown. That is, if the same no. of Task Name is associated with the same Incident ID then it should be displayed once with the count of their occurrences in a separate column say , Count. For example, the Task 'TASK_MANUAL_KCI' got 4 times associated with the same Incident ID INC000000001434. Then the report should display this task one time in a report with count 4. Similarly, for INC000000000943 where task 'IPCG Diagnostic Template' got associated 2 times. The Count is 2 for this task.
Other records should not be displayed in a report.
Would highly appreciate quick response. Please suggest.
Thanks,
Neha Pateria

I tried this Gill, but result is bit different :-
Seems some little modifications are needed. Report should be displayed like the below one where it says how many times the same Task is associated with the same incident. Eg. Task 'TASK_CIRCUIT_RESOLVER' is associated with the incident 'INC000000001434' 4 times. 'IPCG Diagnostic Template' is associated with 'INC000000000943' 2 times. Similarly for other records.
But I really thankful to you for giving me the logic proceed further. I tried '=RunningCount([Task Name]; Row; ([Task Name]; [Incident ID]))'. It gave me desired results. :-
But the only thing that needs to be done is to bring the single Task associated with the Incident..
Thanks,
Neha Pateria

In WM how to clear partially difference in an open storage type with one mi

Hi
I would like to know how in WM to clear partially differences in an open storage type with one mixed bin not totally counted?
thanks in advance
cadanj

Please do the inventory check for the whole bin.Count the each quant of the material. Difference can be cleared.Use following transactions.
1.LI01N-Create Inventory document.
2.LI11N-Enter inventory count.
3.LI20-Clear WM differences
4.LI21-Clera IM differences.
Let me know if u have any other question.
Regards,
PRashant

To multiplicate frequency with one counter

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