DAQmx and USB6008 multiple tasks.

[fuzzzy]

Hi,

Can I use analog and digital  channels in the same time and in the same application?

is it possible to use  analog and digital input or autput togheter in a certain application?

thanks for your help.

[ei0hoda]

Hi

Yes that is possible. I have tried it and I didn't have any problems.However when you use the digital lines you can only read or write to the whole port. For example if you want to read pin 1.0 at your device you will recieve the binary value of the whole port 1.x . But this is just a "problem" when you are using NI DAQmx Base from what I have heard there will soon be a new verison of the NI DAQmx driver that will include the USB devices and this will make it vary easy to programme your applications and you will then be able to read write or read to just one line.

[fuzzzy]

Thanks for your suggestion, really i think it's very unusefull to write or read the whole port everytime..... i'm just downloading new driver version hoping i will be better.

Could you explain wich method do you use to drive digital and analog ports in the same application? I think I should  call everytime a single digital or analog task separately, when I change task from analog to digital for example analog port will continue to work or do they stop working? 

Thanks

[ei0hoda]

Hi

Sorry but I didn't fully understand your question. But try to use the DAQmx Assistent in the new driver version then belive your problems will be solved. I have very shortly tried the new driver just recently and it seems to work very good. However I can't get my DI to work properly can you ? The won't change value no matter what I do ....

Regards
Daniel

[fuzzzy]

Hi,

I'll try to explain you. I'm new in using USB6008 and DAQmx so I'm not skill in using it.

I'd like to use analog input to read voltage of some sensors and drive some relays by digital output and also i've to modulate power supply using analog output.

I saw in labwiev that I can call only one task at time from a daqmx block. now D'd like to understand how can I use these tasks

If I'm using analog output task can I switch to digital input task whil analog output continue working(non reset)? or have I to use different daqmx blocks in the same schematic(one for each task)?

I'll be grate if you could give me a link to a good tutorial to use daqmx and labview.

Thanks a lot

[ei0hoda]

Hi again !

Good turorials are avilable at NI homepage I have posted them below.. If you use the DAQmx Assistent you have to use one block for each type of signal that you need. Lets say that you want to use two analog outputs in the same VI, what you do is that you use one DAQmx Assitent block and add the first of your wanted analog channels. If you then want to add a second one you only edit the properties of your block in the block diagram and add a new task for the second channel (see attched picture). You will then get the two measured voltages from the same Assistent block, use the "Convert from Dynamic data " block to extract the two measured signals. However if you want to add a new digital output or any other signal, except for the analog output, you will have to add a second DAQmx Assistent block anf then choose the wanted signal type.

I have to warn you about a trouble I had with my Digital outputs when I used my USB device. I tried to drive a relay that needed 2.5 mA to drive. The problem is that the DO of the USB device can only drive currents up to approx. 0.67 mA.  This can be solved by connecting a external resistance from the +5 V pin to the wanted DO. You will then be able to drive a maximumk of 8.5 mA. How you should choose your resistance is described in the manual that you recieved with your USB device or at the link below.


A simple and basic guide to Labview with good exampels:

http://digital.ni.com/manuals.nsf/websearch/BF4B45DC473C89AE86256D2C0062711E?OpenDocument&node=132090_US

A complete guide to Labview:

http://digital.ni.com/manuals.nsf/websearch/790127B60590AD0C86256D2C005DCE0F?OpenDocument&node=132090_US

This is a site at NI with good manuals for the DAQmx with USB devices (and a manual for the USB 6008 device):

http://digital.ni.com/manuals.nsf/display?ReadForm&lookup=Data%20Acquisition%3E%3EMultifunction%20DAQ%3E%3ESoftware&view=weblastmonth&node=132080_US

Hope that this will help you, if I'm not answering your question tell me !

[macgregor]

Hi gentlemen!

I also started to use the 6008 and I need to use both analogue in and digital in at the same time. I created and startef the tasks in the beginning of the program and then used them in the program. It worked fine as long as I ran the program in Labview but when I compiled the vi to an executable it gave me an error message.

Error -1073807346 occurred at an unidentified location

Possible reason(s):

VISA:  (Hex 0xBFFF000E) The given session or object reference is invalid.

This is a bit wierd. I think it can be solved if one task is started and stopped before the other is started ("start task" -> "get data" -> "stop task") but this takes like 50 times longer time which is unacceptable in my case.

Have you expereinced this? Do you know if there is a solution or do I need to use two separate DAQs?

Regards
Robert

(ei0hoda: did you study at Chalmers Lindholmen in Gothenburg?)

[ei0hoda]

Hi

Have to say that I don't know how to solve your problem. But a tip is to post a new message with your problem and hopefully someone else can solve it for you.

And YES I studied at Chalmers Lindholmen and I continued 2 years at "stora" Chalmers. You to ?

Regards
Daniel

[macgregor]

Hej

Ok, I have to fiddle around a bit with this and see what happens.

Jag pluggade 3 år med inriktning datorstödd automation. (ei0anro)
Sen läste jag en MSc in Embedded Systems i Edinburgh.

Vilken inriktning gick du?

[ei0hoda]

Tjena !

Jag gick "officiellt" inriktning Telekomm. men jag läste matlab kursen samt givarteknik på datorstyrd automation plus någon till var det nog. Sen gick jag två år till för att bli civilingenjör pga av arbetsbristen. Nu jobbar jag på SKF i gbg med restaurang automation. Vad gör du själv ? Och vad heter du borde känna till vem du är tycker jag

Regards
Daniel