Problemas na leitura de varios canais simultaneamente com placa NI USB-6008

[ap 32]

Ola

tenho o seguinte problema:

estou utilizando uma placa de aquisição de dados NI USB-6008 para o meu projeto

e preciso utilizar 5 entradas e 1 saidas analogicas com sinal de tensão

mas estou tendo dificuldades em fazer o programa ler todos os canais simultaneamente, so consigo um do contrario ele da erro

ficaria grato com qualquer ajuda

obrigado.

segue em anexo a VI onde eu estou trabalhando

[SamboNI]

Hola ap 32,

In the future, please try to post on this forum in English as more people can help you. Also, the multifunction DAQ forum is more appropriate than the LabVIEW forum for these types of questions.

No entiendo completamente portuguese, pero te voy a intentar ayudar en español. Que error exactamente recibes? Yo pude ejecutar tu programa con exito, pero me parece que tienes una cosa mala:

DAQmx Read tiene que ser configurado como "Multiple Channel, Multiple Sample". Ahora lo tienes como "Single Sample"

Tambien, hazte seguro que tus entradas en el Front Panel son en la forma dev1/ai0:3 para esas tres canelas.

Espero que esto te ayude,

Message Edited by SamboNI on 10-11-2007 05:54 PM

[Filipe Silva]

Olá ap 32, bom dia.

Estou lhe respondendo em português, mas como foi dito pelo Sambo NI no post acima, é melhor colocar as mengsagens no fórum em inglês ou em espanhol.

Pelo que eu vi na sua vi, está faltando a indicação de todos os canais utilizados para utilizar as saídas ou entradas analógicas de tensão.

Provavelmente a mensagem de erro que está aparecendo para você é de que o canal está ocupado,  pelo fato de você ter mais um de valor/sinal em apenas um canal que está sendo feita a indicação.

Tente refazer ou alterar adequadamente à sua aplicação. Caso precise de mais ajudas nao hesite em nos questionar.

Não sei se você costuma olhar os exemplos prontos do LabVIEW, mas eles são de grande ajuda para iniciar um projeto. Consulte NI Brazil também à respeito dos cursos oferecidos.

Atenciosamente,

Filipe Martarello

Application Engineering

NI Brazil

[Gabriel.]

Good evening,

I am using two Ni 6008 in my project. Unfortunately, the software hangs and gives the following message:

Error -200284 occurred at DAQmx Read (Analog Wfm 1Chan 1Samp). Vi: 1
Possible reason (s):
Measurements: Some or all of the samples Requested Have Not Yet Been acquired.
To wait for the samples to Become available to use longer read timeout or read later in
your program. To make the samples available sooner, increase the sample rate. If your
task uses a start trigger, make sure That your start trigger is configured Correctly. It is
Also Possible That You configured the task for external timing, and the clock Was
supplied. If this is the case, supply an external clock.

In a project board generates the signal (voltage) to a setpoint hardware, and performs the voltage reading from another. While the second card performs the reading level on the same hardware and three different channels ie Ai are all busy.

Faced with this problem I performed a search on the internet and found the site of Ni the following:

link: http://digital.ni.com/public.nsf/allkb/D02A32CD0F5DCFF7862576C00059222C

Continuous Analog Output boards USB-6008/6009
Hardware: Multifunction DAQ (MIO)>> Portable>> USB-6008, Multifunction DAQ (MIO)>> Portable>> USB-6009

Problem:

Why is my task in my continuous analog output USB-6008/6009 returns:

Requested value is not a supported value for this property?


Solution:

As the USB-6008/6009 can perform continuous acquisition (timed) through its analog inputs, it is not able to provide a continuous analog output. This functionality is limited because of the analog-digital converter inside the device that accepts only timed by software updates up to 150 samples per second. This information can be found in the user's manual USB-6008/6009 located on the link below. The specifications mentioned above can be found in two locations:

    * Analogue Digital Converter: Analog Output section, first paragraph.
    * Update rate: Specifications Section, subsection within the Analog Output on page 20.

For an example of LabVIEW on software-timed analog output, please see the example Gen Mult Volt Updates-SW Timed.vi available in the LabVIEW example finder, Help »Find Examples ...» Hardware Input and Output »DAQmx» Analog Generation 'Voltage.

To do this in C, the sample-MultVoltUpdates SWTimed.c can be found in the following directory:
C: \ Documents and Settings \ All Users \ Documents \ National Instruments \ NI-DAQ \ Examples \ DAQmx ANSI C \ Analog Out \ Generate Voltage \ Mult Volt Updates-SW Timed

Note: The USB-6008/6009 has analog voltage output 0-5V. To prevent errors, please change the parameters of the Channel Minimum Value and Maximum Value to 0.00 to 5.00, and also change the array of waveform-2V to 2V to 0V to 4V. Please see the attached VI, which contains all these changes and is ready to run in a USB-6008/6009 without the need for change.


When opening the file available at the link I realized that to generate the signal was necessary to create an array of 1000 points. Q Something is not possible to do in my project because the value of the DC signal is generated and configured by the user.

Does podeiram help on something ... I'm losing time and possibly by low experience in software

Att

Gabriel