Need to sample CFP-AI-110 modules at 20 hz.

[zener]

Hi,

I am trying to sample and capture in a data file the inputs on a Cfp-AI-110 with a cfp-210 controller.  I have a loop that does an FP read every 50ms.  The data file gets updated every 50 ms, but the data does not change for each channel  for > 1 second. ?? why is this?  What is the maximum rate in which I can aquire these 8 channels with my system?

If I cannot do this with this controller, would it be possible to run my program on the laptop instead, and just poll the cfp for the data at 50ms???

Thanks for any information.

[Wayne.C]

zener,

Most likely cause for the slow update rate is the filter being enabled.  Spec sheet for AI-110 indicates that the update rate will be 1.23 seconds with the 60Hz filter enabled.

[zener · Accepted solution]

Thanks.  Is there a module simular to the CFP-AI-110 I can use that will allow me faster updates?  Even with the channels all set to 500 hz, I can only update at .166 seconds.

[Wayne.C]

The fastest module currently available for cFP is the AI-118 and I have been able to sample at about 800Hz with a cFP-2020.  I'm pretty sure you could achieve your desired 20Hz. 

Just remember as acquisition speeds go up, factors other than the update rate of the module become very important.  This includes things like how fast the controller operates.  For instance, the AI-118 has an update rate of 10KHz but with a cFP-2020 I could only get the above mentioned 800Hz.  NI ran a couple of tests for me with a cFP-2220 which is much faster and managed to get the rate up in the 4KHz range.  Writing clean efficient code will also help. 

[zener]

Thanks for this, Good stuff!