Real-Time Measurement and Control

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NI Crio 9064 - NI 9205 (32AI - not simultaoneous) - NI 9215 (4xAI simultanous) - signals where shown in different diagramms during runtime

 

 

Hello everyone,


I have some troubles with reading analog inputs from the NI cRIO FPGA.


Wiring:


I use differential signals on the NI9205 AI0,AI1,AI2,AI3


FPGA:


I have synchronized a while loop with a SCTL loop by an occurence as you can see in my pictures. On the FPGA i only write the values from the analog Inputs to one FIFO. 4 Analog values came from an NI 9215 (simultaneous) and 4 came from an NI 9205 ( MUX - not simultaneous ). -> 8 channels. I write the values with a frequence of 10kHz.


RT:


On the Realtime system i read the values from the FIFO and show it with a diagramm.

I start the RT-sytem, everything works fine.

But after some seconds, something strange happening. The values where suddenly shown in another diagramm. Its looks like, if the channels were changed during the runtime.

 

You can see a sinewave in the diagramm "Override". If i start the programm, the sinewave is shown in diagramm "Hallsensor" - as it is configured. After some seconds, the Sinewave is shown in diagramm "Override".

 

Can anybode help me, what i dont consider? are there any things, i have to consider, when i am reading some values from a non simultaneous AI like the NI 9205?

 

 

 

with best regards

 

Stefan

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