how many simultaneous tasks can be supported by NI compactRIO

[faisaldin]

Hi everyone,

I m new to modular type data acquisition. I need to acquire about 10-12 simultaneous analog inputs for power quality and transient analysis. As NI CompactDaq specifications provides that it can only allow 7- simultaneous tasks while for NI CompactRIO no such information is mentioned in its specifications.

So my question is how many simultaneous task can be supported by CompactRIO ??

Also plz help me regarding the choice of system type either CompactDaq or CompactRIO fulfills requirements in my case.

[TheGeeze]

Hi,

I think yoiu are misunderstanding the word task. In LabVIEW, a data aquisition task is a group of measurements that have similar properties.  For example, reading in 32 analog signals with the same sampling rate can be one task.  But if you wanted to sample digital and analog signals, you would split that into two tasks.  Also, if you wanted to sample some signals at 25 hz and another at 33 hz, you could split those into two tasks.  

The cRIO is much different system.  It is used much more for Real Time control purposes.  Based on your system description, I do not think this is the right system for you.

The next question I have is what do you mean by simultaneous?  Do you sampling 12 signals at the exact same time so that you could do phase analysis or something similar, or do you mean 12 signals being sampled using one multiplexed ADC?  

Let me know if I have missunderstood your application.

Ryan

[faisaldin]

Hi Ryan,

Thanks for ur answer but i have some more questions regarding same issue....

Firstly thanks for clearifying my concept of task in NI-world.... but question arises that for NI-CompactDAQ USB chassis specifications, it is mentioned that these devices have 3- Analog Input triggering Engines...... as i understand, it allows only three type of analog input tasks of different sample rates....... than how can it support 7-number of simultaneous tasks as you have mentioned that tasks can be differentiated on the bases of their sampling rates  

am i right?? or still missing something........

secondly i need to sample 10-12 analog signals simultaneously so that it allows phase relationship among them as well as transient analysis of these signals  and requieres different ADC for each signal

regards

[TheGeeze]

The three analog triggering engines is correct.  I only used 7 because you mentioned that number previously.

For your application, it seems like you will want 3 modules that have 4 simultaneous samples, like a 9215.  Then you can give each module one task.  Then you can synchronize the three tasks together, so they are all using the same sample clock. 

Ryan

[faisaldin]

Hi Ryan,

what does it means when u said i give each module one task..... for example if i have three modules like 9215, all are sampling at same sample clock why would i need to give each module a different task....... 

As you mentioned in your previous reply that task are specified based on the different sample clock rates..... is it possible that i can only give one task for all of the three modules????

Secondly if NI compactDAQ have 3-timing engines then how can it allows seven simultaneous tasks...... what does it means i cant figure it out plz help me...

Regards

[TheGeeze]

Each module needs its own task.  You can share the same clock amoungst different modules, but you need to create on task per module.  So you could have, lets say, 4 modules using one clock, and 2 sets of 2 modules using the second and third clock.  

Also, you can have some modules that work based on software timing, which does not require a hardware timing engine.

Again, I am not positive where you got the seven simultaneous tasks from, if you could find that reference for me that would help.

[faisaldin]

Ryan,

i need to develop power supply test setup..... these supplies have 3- DC outputs and 1- AC output of different power ratings........ so i need to acquire all of these 8 parameters (4 voltages and 4 currents) and then applying dynamic load on any one or more outputs and get response of overall power supply system........... transient and phase analysis etc............... also i need to apply different loading conditions an all of the outputs and test the supply at its maximum full load condition.........

Now plz tell me that NI Compact DAQ is capable of doing this or not????

My plan is to use NI 9225 and NI 9227 for voltage and current measurements...........

Regards,

[TheGeeze · Accepted solution]

Yes, you will be able to do this with a cDAQ.  As long as you are in one chassis you can share the same timebase and start on the same trigger.  

[faisaldin]

Thanks Ryan......

one more issue im stucked with is...... what is the input voltage ranges for NI-9227 AC and DC both....... no such information is provided in specifications.....

Regards

[TheGeeze]

In the Operating Instructions and Spefcifications Manual, the safe operating input range for voltages are given in the safety guidelines under Isolation Voltages.  Please refer to page 22 for all the information.

Cheers,

Ryan