Digital Relays to DAQ

Hi,
I have quick question you. Can I connect multiple digitals relays to single scb-68 terminal block (DAQ is : PCI 6321)?
Through Labview, I want to turn on or off each of these relays. Is it technically possible? becuase, I never connected more than one sensor to scb-68.
The each of the relay acts as a binary switch to a brushed dc motor (motor voltage 3-12 v and rpm : 11.5 krm with weight < 80 grams). The dc motors will receive power from external dc power supply unit. So the power for the relays (I am thinking) must be from DAQ. But I know DAQ can supply only very very less current. I am trying to source out if I can find relays that run with very current (which could be supplied by the DAq itself) Can you suggest me if this is possible? And also any information or source for the required digital relays would be lot helpful.
Thanks
MSC
Solved!
Go to Solution.

You just need to connect to different channels. Out of the 68 pins going to that connector block, I'm pretty sure there are at least 3 that are digital IO. Check the specs on your DAQ board to make sure.
As far as relays, just go to Digikey and search for a solid state relay that meets whatever switching specs you might have.
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Re: Digital Relays to DAQ

Hi,
I checked through the DAQ Pinout and found this sheet. The terminals are shown as 52, 17 and 49 for P0.0, P0.1 and P0.2. (Image attached below).
And also, what is terminal 8 +5V?? Do I have to connect any of the buffer's ic to it (No need, right?).
And regarding the SW-Timed out program, I have made my boolean array to consit of three led's in the array.
How do I define the lines (channel settings) correctly? is it supposed to be dev1/port0/line2?
Thanks

Hi,
I have a problem in my code. I have connected an NC relay and NO relay in parrallel condition.
In the code , Digital Out SW Timed, I have changed the Boolean array to contain only two switches for two relays and changed the channel settings to 0:1. Now when I am running the program, I have two boolean switches, channel settings 0:1.
The NC Closed relay is running the DC Motor initially (When both the switches are OFF), but when two switches are turned ON or only one switch is turned ON while other switch remained OFF, the NO Relay is running.
But what I wanted is to have a two boolean switches, one switch to control one relay (NO relay), while the other switch is to control the other relay ( NC Closed relay). That is, when 1st switch is turned ON the NO relay must run and while the second switch is turned off (keeping the first switch in ON condition), NC relay must also run. Is this possible?
Please tell me where I am doing the mistake or how to get the program that I want to have. Do you think I did anything wrong with my wiring?
Thanks
Sai

Generate a 12 bit digital output at DAQ output pin

Hi
I have only a little knowledge in Labview
I want to generate a 12 bit digital output at DAQ output pin , from a decimal number. I am using NI USB 6009
Thanks in advance
regards DK

It seems to me that the same question was asked, answered, and marked as solved.
http://forums.ni.com/t5/LabVIEW/Binary-output-at-the-digital-output-pin-as-1111-1111-1111/m-p/249969...

Measure Frequency of Digital Signal from DAQ-Board

I'm using a National Instruments DAQ board and I need to measure the
frequency of a digital signal from my data acquisition board.
I know the measure frequency.vi (In diagram - data acquisition -
counter), but i don´t understand yours implementation mainly in input
"counter". Because i don't understand the relationship of board channel (for
signal acquiring ) and the measure frequency.vi.
Thanks in advance,
[email protected]

Hi,
Attached is a vi which models your signal, and provides a way to measure the average frequency over a window of time. It converts the signal to a sequence of periods. I usually start with this approach because you can save the data in a much more compact form if your sampling rate is high. Obviously over a specified period of time, if there are no zero crossings the frequency is zero, so I was a little incoherent before. The real issue is the latency caused by averaging. Your frequency measurement is most accurate half your window size before the current time, so smaller windows give you more up to date measurements, but also more noisy. If you need the most up to date measurement, then you have to use the time since the last crossing which is the case where the frequency never goes to zero. That's probably not a realistic situation. If you needed less latency, you could use a prediction algorithm.
Also, there are a number of signal measuring and processing vi's that LV gives you, for instance pulse measurements that could be used to partially implement this or other approaches, but I normally steer clear of them unless they fit exactly due to having to convert back and forth to the waveform data type.
Have fun!
Attachments:
DigRandFreq.png ‏62 KB
DigitalRandomFreq.vi ‏34 KB

Relay and DAQ for switching a DC Motor

Hello..we wish to use SPDT relay with NI USB-6008 DAQ card for switching on/off a DC motor. The DC motor has a voltage rating of 122V and current rating of 10A and it is used to pump water. The SPDT relay we have has voltage and current ratings of 12V and 6A respectively. Can this relay be used to directly control the motor, if the relay is energized from the DAQ? Do we need to connect any other component in order to use this relay?

You'll need a couple of relays. You'll need a motor contactor that has a voltage and current rating on the contacts that work for the motor. Many of these contactors have a 24V coil that.
You will need a 24V power supply. Now you need something between the USB-6008 and the 24V contactor. This might be another relay. Or perhaps a transistor driver that can take the 5V DC output from the USB=6008 that will control the 24 V DC coil. A USB-6008 doesn't have enough current capacity (or the voltage) to drive a motor contactor coil directly.
I'd recommend talking to someone familiar with electrical control circuits about your specific requirements.

Capture digital signal with DAQ 6015

I am wondering what is the best way I can capture a digital event accurately using my DAQ 6015 Pad. It seems as though I can only capture it using (on demand) timing which I'm assuming means it will only capture it as fast as the loop iteration. I'm looking to monitor this signal with accuracy down to about 10 ms. Are there any good digital examples i can goto that you can vary how fast you can capture an event using the 6015?

Hi caunchman,
In this card, the digital lines are static so you will have to provide the timing through software, which might not be too accurate. I would suggest using one of the counters of this card to count the digital event. I don’t know what programming language you are using, but if you are using LabVIEW you can find good examples in the NI Example Finder. You can go to Help > Find Example > Hardware Input and Output > DAQmx > Counter Measurements > Count Digital Events. If you are using Visual Studio, C or DotNet you can find the Counter examples here: \All Users\Documents\National Instruments\NI-DAQ\Examples. I hope this is helpful,
Ana P
National Instruments
Applications Engineer

Digital waveform to DAQ

Hi,
I have generate some digital waveform by reading a text file. the graph that is connected to the waveform is what i wanted. But I need to output this waveform through one line digital output of USB6501. How do i go about doing it?
Any help is appreciated. Thanks.
Attachments:
data.txt ‏1 KB
test.vi ‏64 KB

When one looks at the specifications for the USB6501, one notes that it cannot do hardware-timed output. Therefore, you can't use a waveform datatype to generate output with this card.
So, you will have to use software timing and a loop. Since you specify a pretty slow transfer rate (0.5sec), it should work fine.
Look at one of the examples that ships with LabVIEW to get you started. Click "Find Examples...Hardware Input and Output...DAQmx...Digital Generation...Write Dig Chan".
Of course, you only want one line. So when you specify your physical channel, only specify one line. Change the function inside the loop to "Single Channel...Single Sample...Boolean (1 line)". Now the function will accept a single boolean value.
You do a lot of screwing around with getting your data into the right format. That can be simplified a lot. See the attached picture. This is not complete code -- you will need to look at the example I mentioned -- but this picture and the example, combined, should tell you what you need to know.
Hope this helps get you started.

Correct termocouple reading by VI channel test panel but not by DAQ wizards.

1. I am getting correct termocouple readings when using the virtual channel test panel, but not when using labView software created by the DAQ wizards. why and how to solve it?
2. I am unable to switch on 6V relay using DAQ card's output voltage but able to do so using other voltage supply. How to solve this?

In answer to #2, the DAQ card's analog and digital outputs cannot drive
enough current to turn on a relay. What you need to do is use the output to
drive a MSOFET or transistor that will drive the relay. You can use the 5V
computer supply that is available on the DAQ card connector as the power
supply that the MOSFET or transistor use to turn the relay on.
Neal Pederson, President, VI Control Systems
1923 Mendius Lane, Los Alamos, NM 87544
TEL: (505) 662-1461, FAX: (603) 388-4969
[email protected], www.vicontrols.com
"DAQprojects" wrote in message
news:[email protected]..
> 1. I am getting correct termocouple readings when using the virtual
> channel test panel, but not when using labView software created by the
> DAQ
wizards. why and how to solve it?
>
> 2. I am unable to switch on 6V relay using DAQ card's output voltage
> but able to do so using other voltage supply. How to solve this?

Relay for NI 6703

At the previous experiment, I used the relay (sc 2040)
for the PCI-MIO-16E-1. In this time, I am trying to
replace the DAQ for the NI 6703. Could you recommand
me the relay like sc-xxxx?
Thanks.

Hello;
Any digital SCC module that works with the MIO board, also works with the 6703 board. The best bet is to look up in the product catalog for the needed accessories of that new configuration.
You also have the option to use the digital relay SCXI module for more robust applications.
Hope this helps.
Filipe A.
Applications Engineer
National Instruments

Insert a DAQ assistant in producer consumer vi

Hi,
I am using a DAQ assistant to receive the measurements in the 10 digital ports.
Hence I use the DAQ assistant icon in the vi s to get these data in to labview.
Now I require it to convert these digital values from DAQ assistant into analog( this i have done )..
Thse analog values are to be taken one at a time for further processing.
I am trying to use this produces consumer loop for it..http://decibel.ni.com/content/docs/DOC-2431
however i dont know where to fit in the daq assistant .
Do i still need the DAQ create channel , sample clock etc?
or do i simply place my daq assistant in the place of the create channelDAQ icon?
thanks for any help..
iam completely confused as to what to do with it!!...
Regards,
ruser

Hi,
Thank you for the suggestions..
i am sending one vi here..
this is my basic vi which gets the data from the DAQ and converts it into data ( angular info) we require ie angular position data of lower and upper encoders. This is a continuous real time prcess, which will stop when we press stop in the vi.
Now i want to take the a set of data (input and output) each, send it to a vi which will receive this set of data; process it and repeat this for the second set of data etc..
I am also attaching the lvm file . which is the data we are saving now.
The first attachment is the vi where i am getting the data.
The second attachment is the lvm data file.
Thanks.. I would appreciate any help here...
ruser.
Attachments:
absolute encoder.vi ‏805 KB
LabVIEW Measurement file.docx ‏17 KB

Digital

I am with some problems to configure an digital input on DAQ NI-USB 6229. It's a square wave that has maximus frequence of 24 HZ. When I choose 1 sample on demand, it looses some picks of signal. When I choose "N samples", It tells me to choose external clock. I try to choose diclock (digital input clock), but it doesn't work.
Thanks

Hi Eduardo,
You can see on the M series user manual that you need specify one of PFI terminals as your external clock source, when you use external clock to your digital acquisition.
http://www.ni.com/pdf/manuals/371022k.pdf
You can do something like the following example:
M Series Hardware Timed Digital Input Using Counter as DI Clock
http://zone.ni.com/devzone/cda/epd/p/id/4455
Best regards,
Abel Souza
Engenheiro de Aplicações
National Instruments Brasil

Level Control with PID Control & Pulse-Width Modulation

Hi all,
I have attached my program which I'm having trouble wiring up in the block diagram.... I'm fairly new to labview, but basically I have a level control project with an analog input cistern arm turning a pot for my test tank (configured as DAQ assistant voltage analog i/p) and a pump working off a reservoir (configured as DAQ assistant voltage digital o/p). My electrical side of things is working correctly and I have tested both DAQ assistants I/O's successfully off a basic program, minus the PID & PWM... I found a simple PID control subvi which I think I have wired up correctly, apart from the output variable... I also found a bit of code for PWM using the square waveform vi (far right side of the program) which I have tried to include in the program, but I've been unsuccessful with that. The ideal operation i'm looking for with this project is to be able to enter different values for the setpoint, for the PID to kick in to find that setpoint each time using the PWM to drive the pump, which has a flow rate of 13L/min. I have a manual valve to release water from my test tank which I can set accordingly.
My questions are;
- How do I connect the 'output variable' of the PID subvi to my DAQ assistant digital output(both DAQ assistants are set at 1 sample on demand)?
I have a 'number to boolean array' function, but this gives an error saying that the number of tasks generated are not the same...
- How do I wire up the PWM bit of code? Do I need to include the 'error in & out' tabs?
-Am I on the right track with this program or am I way off the mark?!
Any feedback on this would be greatly appreciated. Thanks for your time,
Richie
Attachments:
PID-RichLevelControl.vi ‏91 KB

Rich-MechatronicsStudent wrote:My questions are;
- How do I connect the 'output variable' of the PID subvi to my DAQ assistant digital output(both DAQ assistants are set at 1 sample on demand)?
I have a 'number to boolean array' function, but this gives an error saying that the number of tasks generated are not the same...
- How do I wire up the PWM bit of code? Do I need to include the 'error in & out' tabs?
-Am I on the right track with this program or am I way off the mark?!
You're a bit off track. You need the output of the PID to go into the PWM generator, and the output of the PWM to be written to the digital output. Right now you have the output of the PID connected directly to the Digital Output in a way that won't work, and the PWM generator hanging off the side not really connected to anything. Also, the PWM generator isn't really going to work since you're generating it at the same frequency as your PID loop runs. Try a simpler algorithm such as on/off control first and see if that works for your system.

Beginner question on labview and transducer

i'm trying to understand what a transducer does and what labview can do
to it.
are these assumption correct?
1) with labview, i can change the frequency of sound waves emitted from
a ultrasonic transducer. if i want maximum amplitude of the sound wave
(loudness), i would set the transducer to its internal resonant
frequency (1 mHz) with labview. if i set the transducer to any other
frequency with labview, i would not get max amplitude.
2) input power of the transducer is 100 W which is the max amount of
power i can supply to the transducer. the more power i supply the
higher the amplitude of the sound wave (with 100 W the maximum power the
transducer can handle) regardless of the resonant frequency. Resonan
t
frequncy and the amount of input combined both effect the amplitude of
the sound waves.
3) can labview change the resonant frequcy and amount of input power to
the transducer by itself by simply clicking a switch or turning a dial
on the labview front panel?
4) any good books to help me write a labview GUI for a ultrasonic
transducer to measure the distance traveled and the time taken of a
reflected sound wave in water?
5) what is beamwidth (3 degree) and depth rating (100 m) of a
transducer?
thanks

[email protected] wrote:
> i'm trying to understand what a transducer does and what labview can do
> to it.
A transducer by definition changes one form of energy into another.
Typically it turns some sort of input to a voltage (a microphone
changes sound waves to a voltage) or it changes a voltage
to some form of output (a speaker changes voltage to sound waves).
I am not familiar with the transducer you are using but I will try to work
using
some assumptions and my used brain.
>
> are these assumption correct?
> 1) with labview, i can change the frequency of sound waves emitted from
> a ultrasonic transducer. if i want maximum amplitude of the sound wave
> (loudness), i would set the transducer to its internal resonant
> frequency (1 mHz) with labview. if i set the transducer to any other
> frequency with labview, i would not get max amplitude.
Can not say since I have no idea how your transducer works.
But this sounds reasonable
>
>
> 2) input power of the transducer is 100 W which is the max amount of
> power i can supply to the transducer. the more power i supply the
> higher the amplitude of the sound wave (with 100 W the maximum power the
>
> transducer can handle) regardless of the resonant frequency. Resonant
> frequncy and the amount of input combined both effect the amplitude of
> the sound waves.
Again dont know but this sounds reasonable.
>
>
> 3) can labview change the resonant frequcy and amount of input power to
> the transducer by itself by simply clicking a switch or turning a dial
> on the labview front panel?
Not by itself since LabView is software, you will need some sort of hardware
to connect to the transducer and Labview to control that hardware
>
>
> 4) any good books to help me write a labview GUI for a ultrasonic
> transducer to measure the distance traveled and the time taken of a
> reflected sound wave in water?
>
> 5) what is beamwidth (3 degree) and depth rating (100 m) of a
> transducer?
> thanks
Consider a flashlight. Turn it on and point it at the wall. The size of the
spot it makes
is its beamwidth (or maybe half of that). It is measured in degrees because
it is defined
as the angle between the center and the edge.
I am not sure about the depth rating. Since you are talking about water this
may be
how far down you can put it.
It sounds to me that you will need a few pieces of hardware to accomplish
your task.
1) Some sort of Digital Acquisition board (DAQ) NI makes several.
2) Some sort of amplifier to get the 100W of power.
3) A PC and Labview to tie it all together.
I cant help you with the hardware (maybe some one else here can.) If you
need help
with the Labview portion, this is a good place to ask.
Hope this was in some small way helpful.
Kevin Kent

Edge Triggered Callback Function with E Series DAQCard

Hardware: DAQCard-AI-16XE-50
Software: NI-DAQ 6.9.1 call from C++
Q- Does anyone have sample code to initiate a callback function in C++ when a pulse edge is input to a DAQCard-AI-16XE-50? I am using ACH1 as the input channel. Pulse edge occurance will be low duty cycle.Below code doesnt work..
(I could use a latch & poll but edge triggering would be cleaner!)
status = Set_DAQ_Device_Info(1,ND_AI_FIFO_INTERRUPTS,
ND_INTERRUPT_EVERY_SAMPLE);
retValue=NIDAQErrorHandler(status,"Set_DAQ_Device_Info (FIFO Interrupts)",0);
status = Set_DAQ_Device_Info(1,ND_DATA_XFER_MODE_AI,
ND_INTERRUPTS);
retValue=NIDAQErrorHandler(status,"Set_DAQ_Device_Info",0);
status = Config_ATrig_Even
t_Message(1,1,"AI1",3,1,1,0,
0,0,0,0,(unsigned int)EdgeCallbackFunction);
retValue=NIDAQErrorHandler(status,"Config_ATrig_Event_Message",0);
Thanks Millions if you help!!

Hi kittyKat,
The easiest way to create an interrupt service routine or callback function triggered on a digital edge is to use DAQ Event Messaging. In C, you can program for your DAQ board by using the function Config_DAQ_Event_Message. The different events you can account for are:
DAQ Event type 0 � Acquire or Generate N Scans
DAQ Event type 1 � Every N Scans
DAQ Event type 2 � Completed Operation or Stopped by Error
DAQ Event type 3 � Voltage out of bounds
DAQ Event type 4 � Voltage within bounds
DAQ Event type 5 � Analog Positive Slope Triggering
DAQ Event type 6 � Analog Negative Slope Triggering
DAQ Event type 7 � Digital Pattern Not Matched
DAQ Event type 8 � Digital Pattern Matched
DAQ Event type 9 � Counter Pulse Event
If you are not
using your analog input on your DAQ board, you can setup an analog input and use your external signal as an external clock. This would involve you using one of the shipping examples for analog input with an external clock and adding the DAQ Event Messaging for Event 1 and have the interval be 1 value. Therefore, your callback function will be called every scan or every time your signal pulses high (as the external clock). I've included some useful resources below.
Using DAQ Event Messaging under Windows NT/95/3.1
http://zone.ni.com/devzone/conceptd.nsf/webmain/159C194435C8CA5786256869005EF6AE?opendocument
DAQ Events and Occurrences
http://digital.ni.com/public.nsf/websearch/9F3DAD3E227E4203862566C2005B11EB?OpenDocument
Hope that helps. Have a good day.
Ron
Applications Engineering
National Instruments

Basic Rundown of Digitial IO Techniques with Examples.

Hey Folks:
I seem to be orbing around a solution to what I need, but always run into an error, that it seems nobody else is running into. I think I'm missing something.
Trying to do digital input with DAQ-mx on a PCIe-6535B along the following lines.
Data ----- X_BE56_X_78CD_X_FFE2_X .........
Strobe _____----_____-----_____----___ .........
I'm sending the strobe into PFI5 and the data are going into data ports 0 and 1.
I'm getting a errors along the lines of data timeouts etc along the lines of
DAQmxErrorCannotReadRelativeToRefTrigUntilDone (-200281)
I don't fully understand what DAQ-mx input modes are and I can't find a full write up that goes into depth on all the modes and how they work.
Also it seems that DAQ-mx is self contained. I can't find any write ups or examples on how to size buffers and transfter acquired data into arrays and files so I can actually do something with the data.
I'm using the canned examples, I've attached one, but there's very little explained here. Does anyone have any pointers?
Thanks
Andrew

Hi Blah!
It seems like that error is related to how you are triggering the acquistion. You may want to continously acquire data and then post process or process data based on the Strobe line. The DAQmx Configuring Logging function in the example does log data to file. You will just have to change the Logging Mode control to Log and Read instead of Off. Please take a look at some links for more information on DAQmx.
Timing and Synchronization Features of NI-DAQmx
http://www.ni.com/product-documentation/4322/en/
How Is the DAQmx Buffer Size Allocated for a Finite or Continuous Acquisition?
http://digital.ni.com/public.nsf/allkb/E1E67695E76BA75B86256DB1004E9B07
Retriggerable Analog Voltage Acquisition
https://decibel.ni.com/content/docs/DOC-11757

Digital Relays to DAQ

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