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How to input/output a digital signal and acquire an analog signal at the same time?

Dasylab, version: 8.0.04
Acquirement Card: PCI1002L
 
When I use DasyLab to acquire the analog signals is no problem without digital inputs and outputs,
and when I use DasyLab to input or output a digital signal is no problem also, but when I do that at the
 same time, DasyLab tell me the rate is too high and stop.
 
so, I searched the manual book1 (user guide) for that, it showed me :
To internally equalize measurement time and system time in the analog input, digital input and counter
hardware modules, use the following settings:
   Synchronization: PC Clock
   Sampling rate: <= 5Hz
   Block size: =1
 
the problem is, if I set the Sampling rate to 5Hz, the speed of the acquirement datas is not enough for my
application.
 
so, how to improve it? who can give me a example programm for me. thanks!
by the way, I come from China, my English isn't good, I'm sorry.
 
Allen, China.
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Message 1 of 9
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You can acquire at a higher rate, and reduce the data before doing the output.

You may need to try several techniques to get one that works.

First, have the output signal be a lower rate signal -- not connected to the input.
You can have the inputs update a Global Variable with the desired output, and then, read the variable back and send it to the output, using a slower time base in the Read Variable module (click on the options button in the properties dialog; the DASYLab time base can be configured to a slower rate for output)

Second, if that does not work, try using Average or Separate modules to reduce the number of samples and the block size to one that will work okay.

Who is the manufacturer of the card? Is the output buffered? Have you talked to the vendor who sold you the software?

Measurement Computing (MCC) has free technical support. Visit www.mccdaq.com and click on the "Support" tab for all support options, including DASYLab.
Message 2 of 9
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Thank you very much, I had lost my password for this forums, so I registed a new account.

 

after two years I got more experience of Dasylab, and I tried to do that as your way and I had known more deeper of dasylab today.

 

 

Message Edited by Allen.China on 11-20-2009 12:21 PM
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Message 3 of 9
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Hello Allen,

the PCI-1002xx/PCI-1002xx series is from ICPDAS www.icpdas.com Please check also if you use the newest driver Release (download from ICPDAS homepage) for your DASYLab.

Best regards,

MHa 

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Hi,

 

Have things changed over the years?

 

I need to syncronise a digital output (Modul NI9474) and an analoge input (AI-Modul NI9203) module. I need to measure time intervals from a flank in signal A to a flank in signal B. I would like accuracies of the order of 1 ms. Currently, the signals are not synchronised, with errors of the order of 2 times the block length (block size x sample rate), sometimes much higher. The best I got so far was a block size of around 20 with a sample rate of 1 kHz.

 

If I use the master and slave settings on the RTSL settings, my program doesn't run properly.

If I use digital signals for input and output, I can syncronise them with RTSL settings and everything is good, but I can't always do that.

 

Also, if I do anything in the GUI (such as scrollowing something or going to another window), my output gets screwed up properly.

 

1. What can be done to synchronise AI with DO?

 

2. Is there something that can be done to avoid messing up the output when something happens in the user interface? (I know that I am messing up the outputs as they make some valves switch and that is loud).

 

Thanks in advance!

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Is this a DASYLab question? If not, please repost in the appropriate forum. 

It does not relate to the thread that you posted it in. 

Measurement Computing (MCC) has free technical support. Visit www.mccdaq.com and click on the "Support" tab for all support options, including DASYLab.
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Message 6 of 9
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Well, the original question was how to use digital output (and input) and analog input at the same time. He was also talking about how to "To internally equalize measurement time and system time in the analog input, digital input and counter hardware modules," which I thought has the purpose to sync those signals.

 

Yes it is a DASYLab question, as I am using DASYLab (V13) with those NI modules.

 

I have a problem setting up the block sizes, tasks, etc. to sync the signals properly.

 

 

 

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I do not understand:

1. You want to generate signals in DASYLab, output the signals via DOs, read the signal back via AIs - and the AIs data should be synchronized with the generated signals?

2. Or, the signals are read via AIs, you do some calculations, something is output via DOs?

3. Or, ...?

 

M.Sc. Holger Wons | measX GmbH&Co. KG, Mönchengladbach, Germany | DASYLab, DIAdem, LabView --- Support, Projects, Training | Platinum NI Alliance Partner | www.measx.com
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Message 8 of 9
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- I use a signal generator to fill a digital output module,. The output will switch valves.

- I read in the actual response (pressure) of the valves using an analog input module.

 

In the current setup, the times are not synchronised. I.e. the time difference between the flank in my output and the corresponding reaction in the input signal depend heavily on my block-size.

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