Encoder angle vs analogue inputs

[Carl.G]

I have a 8 way cDAQ9188 chassis and an array of input cards.

9213

9401 x 2

9205

9217 x 2

9203

9237

I using one of the 9401 cards to input a 1024 pulse/rev encoder  (A,B & 0).  The remaining 9401 supplies a timing pulse to this encoder card.  I've had this all working with an encoder only program on the bench and the A,B and 0 work fine converting to 0-360 degrees when the encoder is operated by had, I haven't as yet tried logging at a faster rate when the encoder is back on the motor it came from.

My main issue is I've an array of torque, pressure inputs and flow rates I need to reference against my compressors angle.  Every time I seem to try and up the sample rate I get errors flagging up when I use a combined analogue inputs and encoder program.

I'm assuming all the timing functions for each card need to tie up ?

Do I need more timing inputs from one of my 9401 modules to each analogue card to give them a reference pulse to sample from as they don't seem to sample quick enough.

Any help appreciated as I'm relatively new to all this having converted over from DasyLab.

Can anybody also tell me how fast I can log using signal express and my setup ?

Thanks

Carl

[adlb]

Hi Carl,

As I understand it you have the above setup and it is connected to some piece of hardware and you would like to use the encoder to read back the current position. Then with a known position you can take measurements from the other modules. Also you are feeding the encoder a timing signal from the second 9401 module.

Currently you've built an application that can solely read from the encoder and take no measurements, which works correctly. Was this written in LabVIEW?

Then upon adding in measurements you are receiving errors relating to timing, Do you have the exact error codes you are ecountering?

I think you are right in saying this is likely a timing/software issue. If you could confirm and add to the above we could then look into this further.

Best Regards,

Andrew

Applications Engineer

[Carl.G]

You're understanding is pretty much correct.  The software I'm using is signal express version 6.0.0

As I'll potentially be logging machine angle vs pressures and torques would 1 sample on demand, N samples or continuous samples be used ?

I've added a couple of screenshots.  The frequency inputs are turbine flow meters which work OK, the screenshot was taken whilst the rig was off so it has flagged up a timeout error so I'm not bothered about these.

Everything works when looking at things individually (separate programs) in signal express, I just need to read everything together and at a decent speed to give me angle based resolution.  Hope this helps.

[adlb]

You could use 1 sample on demand alongside some triggering in your code, Alongside this it would be a good idea to synchronise your inputs. The examples discuss particular pieces of hardware but will still be relevant to your application:

Triggering: http://digital.ni.com/public.nsf/allkb/9248D61E22C5C7C586257665005C081E

Synchronisation: http://digital.ni.com/public.nsf/allkb/FA505A35F1D9173286256F3A00663460

Best Regards,

Andrew