Scb 68 counter

I am using an scb 68 connected to a pci 6221.
I require an application where the 16 analog inputs are used to count events. Every analog input has two values (1 or 0) like TTL signals. The problem is that I am using the vi "elapsed time" to measure the time of the events and the time is not accurate nor constant. I´ve read that counters should be used but that is impossible because the scb 68 only has 2 counters and i require 16.
any suggestion?
i've thought on creating my counters physically and use the result with labview, although the utility of the program and the scb 68 card would be negligible.
Miguel Angel

Miguel,
It is hard to tell from an image, but here are a few things to consider:
1. The DAQ Assistant is not considered to be optimized for high performance. It is set up for ease of use. It is often better to use the low-level DAQ VIs. Do the configuration and initialization outside the loop and clear the task after the loop finishes. Just read the data inside the loop.
2. The filters may take longer than you think. It depends on the complexity of the filter and the amount of data. Is the filter VI reentrant? If not you may have issues with the filter transients. If you have the VI Profiler, use it to see where the timing bottleneck is located.
3. Local variables are slower than wires. I do not see the v1.2, c1.2, ... indicators or controls in the image posted. Setting up a shift register to pass the data from iteration to iteration or an Action Engine to pass data from a parallel loop may be faster.
4. Do you need to update the indicators 20 times per second? The user cannot see update quite that fast and it looks like that data is just incrementing. If you only write to the
indicators 2-3 times per second (or, better, yet, in a parallel loop), this might speed things up a bit. Panel updates require OS action and your program has no control over how the OS handles that.
Lynn

Similar Messages

How do I read a pulsed input on an SCB-68 counter channel?

Hello all, I have been searching through the DAQ help and this board
for a few hours now and I cannot find an answer that addresses what
should be a simple problem. Let's start with hardware and software: I
have a 6062E PCMCIA DAQmx card connected to a SCB-68 (E Series)
connector block. I am running Version 7.1.0.306 of Measurement Studio
for Visual Studio .NET and am coding in C#. So please, no LabView
answers.
I am trying to read the pulsed output of the Omega HHT-1501 Digital
Tachometer - it outputs a TTL LOW pulse every time the sensor is
triggered, I would like to read in these pulses and get the
frequency to determine RPMs. As far as I can tell I need to
connect the pulsed signal line to CTR0, which is PFI9/GPCTR0_GATE on
the connector block, pin #3. I have verified that the tachometer is
indeed pulsing correctly. I have used the DAQ Assistant to create a
DAQmx task to acquire the frequency of a digital signal using the 1
Counter Low Frequency Measurement method, input range is set from 1Hz
to 1KHz, starting edge is set to falling. For Task Timing the
Acquisition Mode is Continuous, Samples to Read = 100.
When I run the test I get no response. And it also seems that the
GPCTR0_GATE is always at +5V. I have tried just about every other
combination of inputs, including using CTR1 on GPCTR1_GATE, pin 41, all
with the same result - no signal read.
So what is the problem? Every post or help article I have read makes it
sound like plug and play to read the pulses but this is not the case -
does the counter gate need to be configured as an input in either
software or hardware? Am I supposed to have a signal set on the SOURCE,
and if so what? And what about my ground line from the pulse source? I
have tried attachign that to DGND, still no result, and if I attach the
pulse signal gnd to the GPCTR0_SOURCE it causes my tachometer to lock
up.
This thread
http://forums.ni.com/ni/board/message?board.id=170&message.id=34826&query.id=3937#M34826
seems to be very closely related to what I want to do but is as vague
as the help articles - it mentions using one of the two timebases as
the source input - what does this mean in terms of code/wiring?
Additionally in the NI-DAQmx help article under Device
Considerations->Counter Signal Connections->AO/E/S Series it says
"The count direction terminal must be tristated to use an external
signal. Reset the device to ensure the terminal is tristated" for edge
counting. A) Is this related? and B) how does one tristate by reset?
Power cycling the scb-68 has no apparent effect on anything.
I would appreciate any help on this matter, hopefully with as much
detail as possible since the help manuals seem to be mostly useless for
guiding one in performing any task.
Thanks!
J. Slater

Hi Shyam,
The major factor that would come into play with the signal having some noise is that the counter is expecting a TTL signal and the oscilloscope is measuring an analog input signal. If your signal floats above the TTL thresholds or does not rise/fall within the specifications, the behavior is not predictable and it can be measured as a high or low by the counter. An oscilloscope will measure the analog signal and you may be able to measure the frequency of the noise on your scope by analyzing a smaller timeframe of the signal.
What Is the Definition of a TTL (Transistor-Transistor Logic) Compatible Signal?
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/acb4bd7550c4374c86256bfb0067a4bd
Steve B

Route multiple 6602 counter inputs to one counter output...

Hi!
I´d like to route 4 different ttl signals, that are read by 4 different counter inputs to one single output channel (e.g. the output of one of the counters used) using pulse train generation with a divider of 4. Note that only one of the four inputs is active at the same time, to prevent overlay.
How can I do that with Traditional-DAQ?
Setup would look like this on the SCB-68
TTL1 ----o in0 (ct0)----o out0 TTL(1..4)/4 [Hz]
|
TTL2 ----o in1 -- (output of ct2 is redirected ro ct1)
|
TTL3 ----o in2 --
|
TTL4 ----o in3 (ct3)--
May it be better to just output each counter input signal at it´s own output and connect these outputs to one free I/O-pin hardwired?
Best regards
Zorniki

In the end I configured a counter for Pulse Train generation and opted to change the duty cycle and frequency via 'DAQmxWriteCtrFreqScalar" (i.e. Pulse Width Modulation)
I registered a callback for the 'DAQmx_Val_CounterOutputEvent' and then changed the dutycycle and frequency in that callback.
Unfortunately, I kept getting "The pulse generation with previous property settings must complete a
full cycle before the property can be updated." error messages and, opon further reading, managed to find a doc where National Instruments suggest adding a 'Wait(period)' before executing the 'DAQmxWriteCtrFreqScalar' call.
The problem with this solution is that it one has to wait a minimum of 2 Periods before the Pulse Train can be modified which is not acceptable for our work.
So is there an alternative solution which allows us to change the Pulse Train after only 1 Period ? Is there an event we can trap which allows us alter the Pulse Train after every period ? I'm sure PWM must be possible on Daq cards (PCI-6602 or PCI-6281 or PCI-6259)?
Cheers, Shaun.

Trouble using the counter on PCI 6025E

Hello,
I am facing a problem with the counter on PCI 6025E. I am trying to count the number of pulses generated by the shaft encoder mounted on the shaft of a motor. I am using a channel from the shaft encoder to count the pulses and generate the line state. So, I have wired the channel to pins 25[line state]and 47[counter]on SCB-100. In my application I am using the count events/time vi from DAQ palette. Every time I run my application I have been getting the error NI 10001 saying that the ordering of the strings is not as expected.

Hi,
The Count Events & Time.vi is typically used with older counter hardware such as the 9513 chip. Your E Series card (6025E) uses a DAQ-STC chip. The best way to count your edges is to open up the example "Count Edges(DAQ-STC).vi which can be found by selecting Help>>Find Examples... and you will find it under the DAQ Counter examples as an DAQ-STC example. Hope that helps.
Ron

How do I associate a clock (source) with a (or multiple) counter channels

We are newbies using a 6602 with the SCB-68 interface.
We are reading 8 different TTL pulse trains. We've determined that we need buffered periodic event counting (BPEC) and that we need a common clock (source).
We've used the measurement and automation software to confirm that we can see our signal coming into the card. However, we cannot seem to perform functions requiring a clock (e.g. BPEC).
Question: How do we associate an 80 MHz clock to the source for our counter channels? The the card has clocks, yet our error messages indicate that an external clock had to be used for our task. We may be stuck in the meaning of "external". Though a clock is in the card, is it considered external to my counter channel? Do I connect it via jumpers in the SCB-68 or are there ways to associate it via commands?

Hi NHJared,
There a few examples in the LabVIEW Example finder that will
help you make these measurements. (Help
>> Find Examples >> Hardware Input and Output >> DAQmx
>> Counter Measurements >> Period or Pulse Width)
The DAQmx Timing VI should be set to implicit. This setting will automatically route the appropriate
clock necessary for your measurements.
An external clock is a signal that is created by another device other
than the PCI-6602 and connected through an external pin on the PCI-6602 (e.g. PFI
pin)
Respectfully,
Rob F
Test Engineer
Condition Measurements
National Instruments

Frequency divide by N doesn't work on Counter-Timer PCI-6602

Hello everybody,
I tried to do something basic ( ?) with this Counter-Timer 6602 Board, and it doesn’t work.
So I hope some people with more experience than me could understand what happens here.
1) What I need:
I need to generate 4 synchonised clocks, whose periods will be multiple of 1 ms.
2) What I have:
LabVIEW 7.0 and a PCI-6602 Counter-Timer Board in a DELL PC running under XP pro.
The PCI-6602 Counter-Timer Board has 8 counter timers named CTR 0, CTR 1, ... CTR7.
3) What I have already done, and that worked:
- Generate a 1 kHz “Master Clock” signal from CTR 4, configured by “Continuous Pulse Generator Config.vi” (found in “Data Acquisition, Counters...).
- configure CTR 0 and CTR 1 to work as frequency dividers, by use of “Down Counter or Divider Config.vi”.
- Apply the output signal of CTR 4 (OUT ) to the SOURCE inputs of CTR 0 and CTR 1 by means of physical wiring in the SCB-68 connection box.
When I do this, I get two nice secondary clock signals on my oscilloscope screen, ( with periods = 3 ms, or 5 ms or whatever multiples of 1 ms I choose) from CTR 0 and CTR 1 outputs , very clean and perfectly in phase with the 1 kHz Master Clock.
So far, so good...
But I still need 2 more secondary clocks...
One would say: “No problem, do the same trick with two other counters...” Well, not so simple, it seems...
4) What I tried to do, and that didn’t work:
When I try to do the same frequency division with any of the remaining counters, (CTR2 to CTR7), the program stops and I get an error “ –10020 : Time base not valid “.
I can’t figure out what happens here: I thought any counter could be configured to work as a frequency divider, but it seems not to be so, and I am stuck here.
Has anyone an idea about how to fix this type of problem?
Attached file: hor_div02New.vi
Attachments:
hor_div02New.vi ‏123 KB

karolik,
I'm just adding a followup in English. As Marc L. mentioned, the particular vi named "Down Counter or Divider Config" isn't compatible with the 6602. While the 6602 does have the ability to generate 4 synchronized clocks, a different syntax is needed. Here's how I'd do it:
Traditional NI-DAQ
1. Configure a continuous pulsetrain on CTR 4. Route its output to, say, RTSI 4. Don't start it yet.
2. Configure CTR 0,1,2,3 for continuous pulsetrains using RTSI 4 as their "timebase source." Start them.
3. Start the CTR 4 pulsetrain.
4. Now CTR's 0-3 should generate separate clocks with synchronized phasing.
DAQmx
1. Configure a continuous pulsetrain on CTR 4. Don't start it yet.
2. Configure CTR 0,1,2,3 for continuous pulsetrains using "Ticks" for units. Use a DAQmx property node (probably Channel property node, but am not 100% sure and don't have a LV PC handy to check) to specify that the "ctr4 internal output" should be used as the timebase. Start them.
3. Start the CTR 4 pulsetrain.
4. Now CTR's 0-3 should generate separate clocks with synchronized phasing.
-Kevin P.

How do I get the 1121 card to read the switch and make it a 1 or 0 to count pulses?

Hello,
I am developing a test stand to test tires. We have LabView 7.1 and the SCXI chassis with an 1121 transducer card. I am trying to count the rate and total number of revolutions made by the tire. The signal is acquired from a 12V-proximity switch that is actuated once per RPM. The tire turns at 1,000 RPM or a little more.
The signal will have to go through a 100-foot cable to get to the LabView chassis, will this be a problem?
How do I get the 1121 card to read the switch and make it a 1 or 0 to count pulses?
Will LabView be able to read this many pulses per second?
How do I get MPH and a RPM reading out of it?
Thank you,
James Happe

Hi James,
Since you are cabling your DAQ board to an SCXI chassis with an 1121, you will not be able to use your counters without additional hardware.
The 1121 is an analog input signal conditioning module. It performs filtering and attenuation to help measure analog signals. What it does not have is access to your board's counter pins.
In order to use your counter pins you will need to get the necessary hardware. You have two options:
1) Buy and SCB-68. This is a breakout box that will cable directly to your DAQ board replacing your SCXI chassis. You can connect your signals directly to your counter with this. However, I would advise against this because your application has a 12 volt signal. This will overload the 5v maximum voltage for your counter pins.
2) Buy a 1180 feedthrough panel. This will allow you to use all of your DAQ board's functions with the SCXI chassis. Withouth the 1180 feedthrough panel, the SCXI-1121 is the only thing connected to your DAQ board. Since the 1121 only performs conditioning on the analog inputs, that is all you can access. The other pins cannot be used (no access). With the 1180 feedthrough panel, you can put a connector block on and access all of your other pins (including the counter pins). Again, I would advise against this since your 12 volt signal will overload your counter pins.
My suggestion would be to perform an analog input task. Set up your 1121 in MAX and use a LabVIEW shipping example. In the shipping example select an analog input channel from your SCXI-1121 module. Set the appropriate voltage range and take some measurements. Once your signal is connected and you can read it using an analog input example you are half way there.
Take the analog input shipping example and modify it to perform frequency analysis on the voltage readings. You can simply wire the data from the DAQmxRead VI into one of the frequency analysis VI's (noted in my first post). The output if that VI will give you the frequency of your signal.
-Sal

Wiring a SCB-68 to measure the frequency of a TTL pulse signal

Sorry if this is a basic question but could someone please help me and tell me how to wire up a SCB-68 connector block (connected to a AT-MIO-16 DAQ board) so that I can measure the frequency count of a series TTL pulses (signal from photon counting). At the moment I don't understand how the PFI1-9 connections are related to the GPCTR0/GPTR1 counter connections on the block and how they're all realted to the source,gate and out 1-5 connections on the DAQ board.
Ultimately I want to be able to put this measured frequency into a Labview program with a controllable gate period.
Thanks in advance
Nick

You might want to search the Knowledge Base on the NI's Support Pages for "Cable Mapping for a 68 Pin Connector to a 50 Pin Connector". This should take you to a link that will explain the mapping of a 50way to 68way cable and subsequent lines you are looking for ( reference sub link 68F50M), I guess you have SH6850 cable connected from the AT-MIO16 card to the SCB-68.
Please check out the information about the pin outs, that should help you work out which pins map to the counters, eg GPCTR0_source would be pin 37 on your SCB-68
Regards
Joe (NI)

Count the number of Pluses Generated

we are using the pxi-6602(counter/IO) along with SCB-68.
the problem we are encountering is that,we want count the
number of pulses generated.
we are using the counter0 and generating the
pluse, using the example VI Genrate Finite pulse(TIO).VI
which we are able to capure at the CTR0-out.
we want to count the number of pulses generated at
CTR0, so we have connected to the gate of CTR1
and we are running the example vi Measure Pluse NI(TIO)
we are not able to count back the number of pulses generated.
can any one guide us ....
are we heading in the right
1)is it possiblt to count and measure the number of pulse generated.
2)is it neccessary to specify the PFI line in the measuring/counting.
3)output of one counter is connected to gate of the other counter to measure. is it right
4)since this is the first time we are using counter/timers, please guide us, about connecting the
out and source and gate in scb-68.
thanking you
rags

I'm not at a LV PC now, so I can't look at the examples you mentioned. However, the primary problem is that when you generate a finite pulse train on Ctr0, the DAQ driver makes use of Ctr1 to control the # of pulses generated by Ctr0.
Because you have a 6602, you can simply measure the # of pulses with any of the other 6 counters on board. Ctr1, the one you might naturally think to use, is the only one that won't work.
The method will depend on whether you're using traditional NI-DAQ or DAQmx. The example names sound like traditional NI-DAQ, so the simplest thing is to actually wire from Ctr0 output to your measurement Ctr's Source input. Each of the Ctr's has a different PFI pin as its (default) Source input. Summarizing your questions:
1. Yes it's possible to measure # of counts generated by Ctr0 with any Ctr EXCEPT Ctr1. (Note that if you generated continuous pulses with Ctr0, you could then use Ctr1 to count them).
2. It's possible to specify the PFI line for counting pulses. If you physically wire to the default Source input, it won't be necessary.
3. Output of one counter should be connected to the SOURCE of another counter.
4. Ctr0 Out should be wired to, say, Ctr2 Source. Don't have hw here to be able to identify pin #'s.
Final note: under DAQmx, you wouldn't need any wiring. You can programmatically tell any measuring counter to count the edges on any other pulse-generating counter.
-Kevin P.

Connecting Counter hardware to DAQCard-AI-16E-4

I am dealing with a pulse train signal produced by our hardware with varying period, and am looking to obtain the time between each lo-hi transition.
I have looked at the Count Time - Easy (DAQ-STC).vi within Labview 6 and this seems to give me what i want (the time between the events).
My question is how do i connect my hardware to my DAQCard-AI-16E-4 via the SCB-68?
This is my first time trying to work with counter/timers etc.
Any info appreciated and also other solutions to the problem that i may be overlooking.
Regards Ross

The SCB-68 should have shipped with a big sticker designed to fit under the top cover. Apply the sticker. Now if you look, you should see where the counter-timer connections need to be made on the screw terminals. Consult the DAQ documentation that should have been installed from your NI-DAQ CD for the definitions of the vairous pins. Make sure you only connect TTL (0-5 V) signal levels to the counter-timers. They can be damaged more easily than the analog input channels, or so I've seen.
Also, you might want to post the question over in the Multifunction I/O group.
Dan Press
www.primetest.com

Counter output jumps when power to encoder is cut

Hello all,
I am using a PXI-6251 DAQ board and a SCB-68 to read, via a LabVIEW DAQmx task, an optical encoder (720 counts / rev.) in radians. The data read from the encoder is nice and smooth while the encoder is running, but when the power to the encoder is cut abruptly, there is a jump in the number of radians read (about two or three). An oscilloscope connected at the SCB terminals shows a voltage spike of unreadable height when the power to the encoder is cut. How might such a spike cause a sudden increase in the number of ticks/degrees/radians read?
Thanks!
Slowpoke
Slowpoke
CLAD (believe it or not!), using LabVIEW 8.5
They don't call me "Slowpoke" for nothin'!

Hello Slowpoke,
Large voltage spikes can result in additional counter measurements. The TTL signal that you are measuring has to adhere to certain requirements. A TTL signal is low between the voltage of 0 to 0.8V and a high for 2 to 5V. Additionally, the maximum rise and fall time of the pulse must be less than 50ns. If this requirements is not met, the counter will give erroneous count values. For M-series cards with the DAQ-STC counter asic, the minimum pulse width has to be 10ns. If the signal does not conform to all these specifics, the count value will be incorrect.
One option you can consider, is if you have a 0-5V signal from your encoder that is high when the power is on and low when the power is cut off. This signal can be wired to the Gate of the PXI-6251. What does your voltage spike look like? Is it one large voltage spike or is there ringing/bounching as it settles?
Regards,
Sandra T.
Applications Engineer | National Instruments

Counter input connection

Hi all,
I had DAQ- PCI6259 that connected with Board SCB-68. Now, I want to connect a photosensor with it that can count the number of pulse.
The DAQ has two port for Counter , CTR0- CTR1. However, I do not know which pins should i connect pins for CTR0.
In the SCB-68 , it has some pins relating to CTR0.
Pin2- GPCTR0_OUT
Pin36- DGND
Pin3-PF19/GPCTR0_GATE
Pin37-PF18/GPCTR0_SOURCE.
Which pin should I use for inputs.How to connect 2 lines of the output of the sensor to the CTR0.
Thanks

For normal Pulse counting, connect the high side of your signal to the Source terminal of the counter and the low side to the DGnd.
All of this information can be found in the DAQ Device documentation that gets installed with the DAQ driver and can be found in the NI-DAQ folder in the National Instruments, Start Menu folder.
Ed
Ed Dickens - Certified LabVIEW Architect - DISTek Integration, Inc. - NI Certified Alliance Partner
Using the Abort button to stop your VI is like using a tree to stop your car. It works, but there may be consequences.

Counter Pin-Outs for 6025E

Greetings,
Regarding the 6025E w/ SCB-100, what are the normal I/O pin-outs one uses for the 2 counters? DIO 6 and 7 can control the counter. GPCTR0_OUT and GPCTR1_OUT I presume are the pinouts for pulse trains,etc. Is this correct? Would GPCTR0_SOURCE and GPCTR0_GATE then function as inputs?
My immediate use for these pinouts would be a frequency input TTL count on counter 0 and a PWM signal output from counter 1. I'm finding the information in the 6025E user manual quite confusing. Would somebody please be so kind to point me to examples or a discussion that detail which type of pin-out to use where?

By default, GPCTRX_SOURCE is the source and GPCTRX_GATE the gate for the counter X (X = 0 or 1). But you can use other PFI lines instead of these defaults inputs.
The outputs cannot be set to other pins than GPCTRX_OUT.
DIO6 is the default auxiliary line of counter 0 and DIO7 of counter 1. They will set the direction of counting when the counter is configured for position measurement (UP/DOWN counter).
If not already done, I strongly recommend you to install the improved counter palette.
There are a lot of examples that ships with LV. They will help you to start your counter application. For LV7 : LV Menu --> Help --> Find examples --> Hardware Input and Output --> Traditional DAQ --> Counters --> DAQ-STC.
Measure Frequency (DAQ-STC).vi not only shows how to measure a frequency but also how to set non default values for source and gate.
Both counters of the PCI-6025E are needed to measure a frequency and therefore it will not be possible to run another counter task at the same time. One counter is configured for simple event counting and will therefore count the pulses on its source. The counting is gated by the second counter that is used to generate a single pulse.
Frequency [Hz] = Number of pulses / Measure time [s]
The duration of the measurement is very accurate because it is given by hardware (internal timebase of the counter).
If the frequency of the signal is low, it will be more accurate to measure the period of the signal --> Measure Period (DAQ-STC).vi.
This method requires only one counter. The source of the counter is the internal timebase and the external signal is used to gate the counter. (number of pulses of the internal timebase between two rising or falling edges of the signal).
The numerous advanced DAQ counters functions allow you to go very deep in detail and I recommend you to go through some of the examples that ships with LV or that you can find on ni.com.

What needs to be done in order to bring in a signal to a SCB-68 and have the SCB-68 caculate the frequency, etc. using a PCI-6052E board in LabView?

I am using a basic function generator to create a signal to channels ach0,ach1,& ach2, using resistors as a way to change the signal a bit. I have built a VI to see these three waveforms, but I'd like to be able to use the internal counter of the SCB-68 to measure the pulse width and be able to convert it into a frequency measurement that can be displayed on the front panel. I've looked in the NI 6052E manual, but it is very vauge. Any help would be useful. Thanks
SQ

Hello;
First of all, you need to make sure the three waveforms are TTL leveled, since the counters only support that data type.
After you clear that out, you will need three counter to do frequency measurements on the three waveforms, and the board you have there has only two counter available.
In case you have the thre counters, you can connect the pulse trains on the gate input of the counters, and use one of the two timebases to be the source input. You need to configure the counter to do buffered event counting. Then, the number you catch in the buffer will be the number of pulses that elapsed in between two active edges of your pulse train. Since you will know which time base you chose, you can do a simple math to calculate the total time.
Hope this
helps.
Filipe A.
Applications Engineer
National Instruments

Scb 68 pinout - eseries devices vs tio

Im waiting for a scb 86 to get delievered for my counter board.
I do have the cable which connects to the board to the scb 68.
While Im waiting, i noticed we have a scb 68 for or pxi station.
The cable is different on one end to the pxi box, but the other end looks the same.
According to the quick refernece pinout guides, they appear different.
For example, on the scb 68 quick reference label for tio devices, pin 12 is pf13 but
on the scb 68 quick reference for the e series devices, pin 12 is d gnd.
Im wondering though, is this difference in the cable or in the scb 68.

they appear to be just different cables are per the spec sheet
http://www.ni.com/pdf/products/us/4daqsc212_216.pdf
so im all set..
Message Edited by jimmyinct3 on 11-02-2009 08:53 AM

Scb 68 counter

Similar Messages

Maybe you are looking for