acquire signals with shaft encoder rt

[ashvin0703]

Dear Forum members,

I have a cRIO and using RT to acquire  pressure, temperature, speed and torque signals. I'm also using  a shaft encoder of which one of its two channels gives 360 pulses per rev ( 1deg per pulse). I want to acquire another 2 pressure signals per every degree say for 2 to 3 revs. The problem I'm facing is, being inexperience in labview RT, that I'm not too sure how it is done. I have tried to search for examples and could not find any or may be I have not search in the right place.

I would be much aprreciated if you could guide me where to look for it. I have attached an image of the main part of the block diagram.

Regards,

Ash

[P@Anand]

Are you asking about the logic to read the pressure transducer value? The speed you are reading is a calibrated value ( conevrted to Engineering unit - rpm)?

I see the configuration of your timed loop as 1KHz and the dt is 1000 so you are iterating the loop every 1 second, not a right approach. Since you have the RT controller you can go for 1KHz with dt = 1 without any problem. Also do not pass the error wire sequentially it may slow down your execution when you are going at a higher rate.

What is the max speed at which you will run? Any specific requirement of acquiring pressure/degree rotation?

[ashvin0703]

Hi P Anand Thank you for your reply. Yes I want to know the logic of how to acquire a signal with respect to the shaft encoder pulse. There are 360 pulses per rev and and want to get pressure signal every deg. The max speed I wan to run is 6000 rpm. The speed is a calibrated one. I have used the timed loop mainly for the torque signal. In my code I will get 100 measurement points and then the loop will sleep for 900 ms. Is this correct? I just want to get an average over the 100 points. I have recently purchased this shaft encoder and may be I can average its signal over one rev.

[P@Anand]

Its bit tough one. See you are running at 6000rpm that means 100 revolutions per second and 0.1 revolution per itertation ( if your loop is running at 1 KHz) so for every iteration you will get 36 degrees at the same timeyou should have taken 36 samples of the pressure value. So in order to achieve this you need to run the loop at 40 KHz.

For torque if you run that much slow you don't need a timed loop. why you keep the loop idle for 900 ms?