2 encoders 1 DAQ sync via rtsi for ellipsometer

[Matt P]

Hey, this is my first big project. I need to program an algorithm to find a null in light intensity by crossing two polarizers. I rotate the polarizers with flexmotion and need to syncronize encoder positions to AI over an E series board. Both encoders may move back and forth a few times before I find the null. I would like to have voltage, and two encoder positions syncronized into an array. Any recommendations?
How should I begin to test my rtsi cable setup?

[JoshuaP]

I have found that the best way to do this is to use a 660x witht he encoders and use the e-series for the AI. Then set the encoders up for buffered position measurement. Buffered position measurment latches the value of the count everytime a pulse is recieved on the gate pin.

This is really nice, because you can route your AI scan clock to one of the RTSI lines and then set the Gate for each counter to that RTSI line. This way everytime you scan an analog input you will get the value of both counters. In addition, the counters will be sampled at a percise time so that you can measure things like speed and acceleration.

I am not sure what programming language you are using, but you can combine some of the LV shipping examples like ContAcq&Graph wit
h the buffered position measurement. All you need to add is the route signal.Vi to route the scan clock to the RTSI line. I will include an example in VB.


I hope this helps.

Joshua

[Matt P]

Thanks, My equiptment: PCI 7344 to drive. E-series is AI. Programming in Labv 7. I assume 660x is a PXI counter\timer module? What if I cant afford this board? My plan was to sync pulses from the flexmotion encoders through rtsi to the DAQ as is done in RTSI_with_DAQ_(encoder-external_scan_clock) in devpmt zone. your method will latch both buffered encoder measurements (counters) to the 660x clock which also latches DAQ? That sounds good, if I have it all right. Again, thanks for you help and patience, anything you introduce me to is worthwhile at this point.
MP