Experiment setup : measurement setup and

[紫星天龙]

hi,everyone

 I am reading Dasylab tutorial documment about Experiment setup,but the follow Note confuse me so much

Note  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: £ 5 Hz
• Block size: = 1

so i can not change parameter settings(sampling rate ,block size)? it seems so absurd...

anyone can explain why? thanks a lot

[MHa]

Hardware sub types without there own hardware clock (analog input, digital input, counter input in polling mode) needs a software based synchronization clock source. The "old" Driver Toolkit based drivers for DASYLab - you use this driver interface with your hardware - support only the settings ( Synchronization: PC clock, Sampling rate: £ 5 Hz, Block size: = 1 ). Drivers based on Extension Toolkit, for instance MCC-DAQ, NI-DAQmx have more features to set the timebase for these hardware sub types.

Best regards,

MHa

[CJ_Butler__DASYLab_Pro]

Can you tell us more about the setup?

What is your DAQ card?

What driver did you install to use it?

What version of the software are you using (use, Help-->About DASYLab for this information).

What do you want to do?

[EB_75]

Hello,

Thans for these explanation.

I'm also confused with the "measurement setup" menu. Using a Daqmx device, is it relevant ?

And a second question : in a dasylab worksheet (designed with for eg 4 daqmx modules (Ni -USB 6008)), what is the sampling period of the worksheet regarding each module ? in the dasylab help, it's mentionned a "module management list" which dispatches CPU time. but no value.Is it the measurement setup value ?

Thanks.

EB

[CJ_Butler__DASYLab_Pro]

When using NI-DAQmx, you are creating "Tasks" in the NI Measurement and Automation (MAX) application.

In these tasks, you are defining the sampling rate - samples to read - type of sampling (1 sample on demand, n samples, continuous).

When you open DASYLab, it reads the list of available tasks, and allows you to use them.

When you create the NI-DAQmx Analog input module, you can select any available Analog Input Task from a list. The sampling parameters (measurement setup) is already defined by the task.

Depending on your settings, you may be able to "override" the task parameters and select different sample rate and samples to read. In DASYLab, the "Samples to read" is the block size. 

In the Measurement Menu, there is a Hardware setup and a Measurement setup. It will have one or more options - Driver and NI-DAQmx, possibly others, depending on how you installed the drivers.  The NI-DAQmx submenus give you additonal options, including the ability to re-synchronize with MAX. 

For your DASYLab project, you should first create one or more tasks using MAX, defining the number of channels, channel configuration, and the sample rate and samples to read. You can test the task to verify that it is correctly collecting your data. 

Once that is done, open DASYLab, create a NI-DAQmx Analog Input module, and open its properties to select the correct task and configure the module to have the correct number of channels. Generally, you should not do anything in DASYLab to change the sample rate or the samples to read. MAX is the best place to do that. 

[EB_75]

Thanks for your quick answer.

I guess I understand what you explained. But my question was not clear.

In Dasylab, in the function bar, there a button labelled "A/D". once clicked, you access to a window with a "general sampling rate". this is the same value than the drriver sampling rate in the time base settings. So it's for old devices as yo explained to someone before. Am I right ?

My second question is about the rate or frequency, Dasylab acces to the usb modules.

If the worksheet uses two modules, I guess dasylab accesses to these each at one time. but how often ?

Thank a lot.

EB

[CJ_Butler__DASYLab_Pro]

The buttons on the DASYLab  function bar (A/D and the green hardware button) are for the installed legacy driver ONLY. This will be the IOtech driver or the Sound Card driver or the Demo driver.

All NI-DAQmx settings for hardware configuration and measurement setup are done outside of DASYLab, in MAX. These are your task settings. A task is a combination of device channels, scaling, sensor configuration, and the sample rate and samples to read (block size). For advanced applications, you can use triggering or advanced features, depending on your device.

If you have two devices, you should first try to configure both in the MAX task that you create. Then you only need one NI-DAQmx Analog Input module, and both devices use the same timing.

If MAX doesn't allow both devices in the task, then you must create two tasks, one for each USB device. In DASYLab, you will create an NI-DAQmx Analog Input module for each TASK.

Any NI guys following this? Can you give a clearer explanation of how the tasks work in MAX?