3 analog output scb 68

[neutron]

Hi there,
I am a newbie in Labview and trying to generate three different analog signals of different voltages usin PCI 6733.


Q1 ) Is it possible to control them induvidualy at various instance during generation without any flaws.

Q2 ) Does SCB 68 have provisions for more than 2 analog outputs?

If not, I have a additional PCI 6143 card and another SCB 68 block. Could a solution be obtained using these additional elements ?


With Regard's
Neutron 🙂

[AlanArmstead]

Hello Neutron,
Yes it is possible to update individual channels of an analog output. What you actually will be doing is writing the same values to the channels you don't want to change and new values to the channels you do want to change. Take a look at the attached program. This example is written with two ao channels, but could be edited to incorporate a third channel rather easily. As for your second question, the SCB68 can be used with your PCI-6733 for more than just two outputs. The terminals of the SCB68 just "break out" the pins of your PCI device. Terminal 1 of the SCB68 is pin 1 of your board. So, looking at the pinout of the PCI-6733 (link below), Analog Output 0 is pin 22, AO 1 is pin 21, AO 2 is pin 57, etc., which map directly to the terminals 22, 21 and 57 of the SCB68 respectively. I hope this clears things up!

PCI-6733 Specifications
http://www.ni.com/pdf/products/us/4daqsc362-365_372-373_368.pdf

-Alan A.

[stail]

Hi,
I am also a newbe in LabVIEW and to work on my Thesis I have to try to write a program using it to acquire data from a PCI 6143 card. I have to deal with four different channels and I have no idea how to set up the program. I tried to go through a lot of different tutorial but they all did not make me comfortable with the program itself. I just tried to understand the file attached from Alan and I was wondering if mine should somehow look the same. I thought I have to use the DAQ assistant and then include the different channels but that doesn't seem to work. How should I set up the program? Has someone written a program than can do such acquiring data processes or can someone share a link to a tutorial that deals with exactly this kind of problems?

Thank you for your posts.

/stail

[Chris_D]

Hey stail,

Alan's example is for Analog Output, while it sounds like you need to do Analog Input. Also, his example was designed to allow you to update different channels individually, while your example will be much simpler than this.

What problems were you having with the DAQ Assistant? This is definitely the easiest way to set up data acquisition for beginners. It should be as easy as selecting Analog Input, selecting the 4 channels you wish to acquire on, setting your sampling rate and acquisition type, and hitting OK. You can then wire the output of the DAQ Assistant to a Waveform Graph to graph it or Write To Measurement to write it to a file.

I realize that you have read through many tutorials, but have you seen the one below? It gives a good intro on the DAQ Assistant.

NI-DAQmx Express VI Tutorial
http://zone.ni.com/devzone/cda/tut/p/id/2744

[stail]

Hi,
first of all I would like to thank you Chris_D for the offered tutorial. I did go through that one and what I came up with is attached in a screen shot I took. I am not sure if I should have a loop around the whole setup? And maybe there are some ways to improve the accuracy of this file by adding some more detail to it. Right now I don't have a trigger attached to the pci card so I am unable to write any data because of the missing trigger signal. What do I have to exchange it with to be able to save/write data. Is there a possibility to just press a button and then the programm starts working?

I appreciate your answers and want to thank you in advance

kind regards

/stail

[Chris_D]

Hey Stail,

I wouldn't recommend putting a loop around the entire setup. Right now your program is setup for finite acquisition, meaning it will acquire a finite number of samples and stop. If you would like to continuously acquire your data then you will need a loop, but not around your entire setup. One other useful tool is the NI Example Finder in LabVIEW. You can navigate to Help » Find Examples » Hardware Input and Output » DAQmx » Analog Measurements » Voltage, to see many examples that will serve as great starting points for your applications. You can find examples for both finite and continuous acquisition here.

As far as your trigger goes, it sounds like you don't need a hardware trigger. You can actually just delete that triggering VI and wire the Timing VI directly to the Start Task VI. This way your acquisition will begin right when you start your program.

[stail]

Thanks for the answer,
I figured a way out how it works. To just testrun the program you are right that I can do it without trigger but afterwards, when I will do the measurements with the engine I need a referens point so that I know where the crank angle started. But this will be provided by my lab so I don't have to worry about that. At the moment I am just using my beam chopper as the trigger. I attached the program I am using and I was wondering if someone can tell me how I can monitor two different inputs at the same time. In my case this would be the IR detector and e.g. the beam chopper? I know I could just write another program that does that but I want to monitor the changes inside the program whenever I e.g. change something in the alignment. It is also not just about the monitoring it is also about matching those two signals.

Thanks for the help

/Stail

[Chris_D]

Hey Stail,

You actually use the same task you have already created to monitor more Analog Input channels. On your front panel where you select your physical channels scroll up and select Browse. You can then hold Ctrl and select multiple channels for input. Note that you will only be able to select multiple channels that are of the Analog Input type since this is how you have defined your task. You would have to create a new task if you wanted to do Analog Output or DIO.






Message Edited by Chris_D on 04-02-2008 10:03 AM

[stail]

Hi,
Thank you soooo much. You have been the greatest help ever. Finally the program is working and I can do my measurements!! Thanks for the big relieve I am just going through. I really appreciate it.

Best wishes

/stail

[alieas]

Hai .... This is Manick..... i just seen the answers given by you regarding SCB68.... eventhough i am new to Labview.... i just need to know ... i wan to take Analog Input and Analog Output from SCB 68 which using with NI7830R card..... now i want to know how to i Mapped this two hardware.... next i want to creat e a VI to read the samples... i reffer so many document .. but i couldnt get right answer ...will you help to solve this...?