USB-6008 Quadrature

[NMC10]

Forgive my ignorance, I'm pretty new to all this...

I'm trying to read a quadrature encoder through my USB-6008. I have been able to create a VI that allows me to view the counts on CHA through the PFIO port on the 6008. Do I need a different DAQ with a separate counter to read my CHB and thus determine direction the encoder is turning, or is there another input I can use for this?

Thanks for your help,

Nick

[Brian_P]

NMC10,

The USB-6008 only has one counter on it. The specs for the 6008 can be found here.  In order to do a quadrature encoder you need a card that has at least 2-counters on it.  

Brian P  

[John_P1]

The number of counters doesn't really matter, you just need a daq product that supports encoder tasks (or at the very least, a daq product that supports using an external signal to determine count direction).  The 6008 does not support encoder tasks or external count direction control.

The NI myDAQ is an example of a product with a single counter that also supports encoder tasks.  It is intended for students, so it may or may not be an option for your application.

Best Regards,

[joro11]

I am wondering can the encoder be read with the new NI USB 6002 https://www.ni.com/en-us/shop/model/usb-6002.html? I need the position not only the pulses. 

[John_P1]

I haven't yet used the 6002 myself, but according to the manual it looks like the counter is only capable of edge counting and not taking encoder measurements.

Best Regards,

[joro11]

I believe it is not the problem of counting let us say the front edge but that it says that it can count only up. I was wondering whether the other PFI can be configured as a direction for counting. Also I do not know if the counter is not bufered how can I organize my LabView program? I will execute a cycle 10 times/second reading and controling hardware (PID control in some cases) and in the meantime the encoder is rotating and how I will not loose my counts and position? I am now considering some hardware that can transform encoder position to analogue voltage with 14 bit resolution. Or using a multiturn potentiometer as a second sensor. The encoder is on the back shaft of the motor for velocity feed-back and I consider splitting its signal.