DAQ

[vultac]

Hi im using 1208FS from measuring computing...and would like to ask how isit possible for me to acquire the signals from the DAQ? are there any useful websites????? thanks. Im completely new to labview

[Dan DeFriese]

QUOTE (vultac @ Nov 11 2008, 10:00 AM)

Hi im using 1208FS from measuring computing...and would like to ask how isit possible for me to acquire the signals from the DAQ? are there any useful websites????? thanks. Im completely new to labview

Measurement Computing has what they call the Universal Library for LabVIEW which is available on their website. (It may have come on your hardware driver CD also.)

Evidentently its free now (used to be $50). I'd first check the library for example code.

Also note that at one point, I think Measurement Computing was parntered (taken over maybe) by NI and they were going to support some of the products with DAQmx. This may be the case for your 1208FS (USB DAQ) gizmo.

~Dan

[vultac]

yah..i looked into those already... but im completely new to labview...for example i dont even know how to acquire an analogue signal and display it using labview....

[Dan DeFriese]

QUOTE (vultac @ Nov 11 2008, 11:23 AM)

but im completely new to labview...for example i dont even know how to acquire an analogue signal and display it using labview....

This being the case work through the "Getting Started with LabVIEW" manual. IMHO NI's LabVIEW documentation is top notch compared to other environments.

You can get to it from the online help or directly at C:\Program Files\National Instruments\LabVIEW x.x\manuals\LV_Fundamentals.pdf on your system (x.x is the labview version number).

[vultac]

thanks mate. but do u have any idea how could i convert my analogue signal into digital form?

[Dan DeFriese]

QUOTE (vultac @ Nov 11 2008, 06:29 PM)

thanks mate. but do u have any idea how could i convert my analogue signal into digital form?

What do you mean? I didn't check the specs on your 1208FS but it probably has a couple analog inputs. I'll look it up and get back here.

What exactly are you measuring?

[jdunham]

QUOTE (vultac @ Nov 11 2008, 04:29 PM)

thanks mate. but do u have any idea how could i convert my analogue signal into digital form?

I have to point out the hardware vendors pay their tech support staff to help you get through the initial start-up with their equipment. It's noble of Dan to be helping you out, but you really should call your vendor to get basic help like this. Even if you got the card second-hand, you can frequently get them to help you out because they want you to buy your next card from them too.

When you get to something tricky where the vendor support technicians may not know the finer points of advanced use or application-specific concepts, then you might find an experienced user here who is able to help.

Good luck.

[vultac]

actually im trying to acquire a signal from the analogue inputs and convert this signal(analogue form) into digital form....

Im in the UK now..it would be expensive to call to US from here! ><!

[jdunham]

QUOTE (vultac @ Nov 11 2008, 05:19 PM)

actually im trying to acquire a signal from the analogue inputs and convert this signal(analogue form) into digital form....

Im in the UK now..it would be expensive to call to US from here! ><!

Well they have email too (http://www.measurementcomputing.com/tech.html), and there's always skype.

If you card is working, then the signal is already digital once you do any kind of acquisition. The vendor should have some example programs you can test out. If the examples are not working, then your best bet is to contact MC. I don't mean to drive you away, but honestly you are going to get up and running faster with them.

There could also be also some confusion about terminology. Your computer can only measure an analog signal by digitizing it, but it it will still have an "analog" appearance on your computer screen. You'll still see a sine wave if you have a sine input (though if you zoom in hard enough, you will see that it is digitized. If you are trying to express your input data in some other digital way, you may need to write some more software. You can also post your work so far and some screen shots and people could give you more help. But you should really be working with your vendor's tech support if you don't know how to use the hardware at all.

[Dan DeFriese]

I just skimmed the manual and there is also a forum with a similar format to LAVA at http://forums.mccdaq.com/. Kinda neat, lots a projects in there. But there's nothing like a good manual and little experimentation.

From the fs1208 manual:

It doesn't get any simplier than that. I didn't look at the latest SW manual for Universal Library (the $50 hardcopy was good) yet, but I imagine its just as easy on the eyes.

~Good Luck

[vultac]

ACtually my project involves...acquiring an analogue signal from a sensor then converting this signal into digital outputs..... ssome sort of camera thing...dont know how to start man....in programming terms i might have an idea...but using labview....:/!!!!!!!!!!!!!!!!!!!!!!!

[Dan DeFriese]

QUOTE (vultac @ Nov 14 2008, 07:29 AM)

ACtually my project involves...acquiring an analogue signal from a sensor then converting this signal into digital outputs..... ssome sort of camera thing...dont know how to start man....in programming terms i might have an idea...but using labview....:/!!!!!!!!!!!!!!!!!!!!!!!

1) Determine what the output of the sensor/transducer is.

2) Determine what the input requirements are for your DAQ device.

3) Determine what signal conditioning is needed (e.g. amplification, attenuation, etc...) based on 1 and 2.

4) Plug it together.

5) Then LabVIEW that SOB .

I realize this is easier said than done, but you have to read the manuals, experiment, decide on a course of action based on your understanding, then get-r-done! Trust me, this is the only way.

Good Luck

[vultac]

hahaha thanks dan. will try to work on it... will keep on updating ya.. btw do u hav msn or something?

[vultac]

Hi, Ive attached what i have done so far. I think im able to acquire the analogue signal.. but how can i convert this analogue signal into digital signals?!?!

[Dan DeFriese]

QUOTE (vultac @ Nov 14 2008, 11:54 AM)

how can i convert this analogue signal into digital signals?!?!

Could you elaborate on what you mean by digital signal? As stated earlier, your DAQ has already digitized it so the PC can access it.

[vultac]

hmmm..cos right now i only can see the DC waveform(analogue voltage) like for eg 9V..... i want it to display 1 or 0's... my resolution i think its 12 bits....so yah...how do i display the digital waveform out?

[Dan DeFriese]

QUOTE (vultac @ Nov 14 2008, 05:28 PM)

hmmm..cos right now i only can see the DC waveform(analogue voltage) like for eg 9V..... i want it to display 1 or 0's... my resolution i think its 12 bits....so yah...how do i display the digital waveform out?

Ahh ok, It sounds like you just want to change the radix... Right click the numeric control and select Visible Items -> Radix. (note that the control must be an integer representation for this option to be available). This will display the radix selection on the left side of the control. You can use the radix selector to show the value as decimal, hexidecimal, octal, and of course binary.

You can also use the Number to Boolean Array function to convert the integer into an array of booleans.

Hope this helps.

[vultac]

hi dan, thanks for replying...well i just remember my sensor has got arrays which contain analogue voltage...and how can i extract these arrays out to analyze having only one analogue input to the DAQ?

[Dan DeFriese]

QUOTE (vultac @ Nov 18 2008, 01:04 PM)

hi dan, thanks for replying...well i just remember my sensor has got arrays which contain analogue voltage...and how can i extract these arrays out to analyze having only one analogue input to the DAQ?

I'm not sure what you mean by "the sensor has arrays". However, if you wish to get a particular element of an array use the "Index Array" function on the array pallete.

[jdunham]

So if it's a camera, you would typically acquire your analog to digital value in a double (nested) FOR loop, with one loop for rows and one loop for columns. Wiring the voltage out will give you a 2-D array of pixel intensities. You would run that once for each frame you capture. Then you can use lots of other labview functions to process the 2D image array. If you wire it to a 2D intensity graph, you will see your image (you may need to transpose the array and/or reverse the axes.

Ok, so most people who want to acquire data from an array sensor like a camera will use frame grabbing hardware which does this all for you. Billions of dollars have been spent making this easier and many orders of magnitude faster than what you can do with a measurement computing daq board one pixel at a time.

So vultac, I think you need to tell us some more about what you are trying to do and why might need to reinvent the wheel. If it's a school project, well that's cool, but you still need to give some more information so that an appropriate level of help can be provided. If it is a paid job or a project for fun, then giving some more information will still help you arrive at a reasonable solution at a much faster rate. I'm sorry if I'm totally misinterpreting the situation, but you haven't given us much to go on.

[vultac]

hey guys sorry for being vague...i wasnt completely what i was supposed to do till few days ago...well this is a project which i have to do.....now i need help on controling the digital lines of the DAQ....isit possible to display digital timing diagrams on labview? and ammend them to go high or low like what codas can do?