Interfacing Lego NXT motor to sbRIO-9636 Eval Board

[jimmyservo]

Hello,

Being a newbie to sbRIO, I would like to build a simple Quadrature Counter.  

Recently I attended the excellent Build Your Own Embedded System Workshop and have a sbRIO-9636 which is running a modified Quadrature Counter NI example project originally designed for the sbRIO-9631.  It is working great using the digital encoder built into the daughterboard.

Next I want to use the encoder of a Lego Mindstorms NXT motor (PN 9842).  I will power the motor externally so for now I just want to up/down count the encoder.  Here is the wiring I plan to use on my daughterboard:

Channel A (yellow wire) of the encoder will go to DI2
Channel B (blue wire) of the encoder will go to DI3
0V Common (red wire) will go to DGND
+5VDC (green wire) will go to ???

So that's my question: is there a point on the daughterboard of the sbRIO-9636 that I can safely connect to for +5VDC encoder power?  By the way, these wire colors are from the Lego Mindstorms extension cables when they are cut and stripped.

Any help would be appreciated!
jimmyservo

[jpeggins · Accepted solution]

According to the quick reference for the sbRIO 9636: http://www.ni.com/pdf/manuals/375933a.pdf

there appears to be +5VDC on pins 49 and 50 of the J502 connector. Is this connector available or are you using a daughterboard?

Other options would be more hackish IMO, such as drawing the 5V from the USB connector.

[jimmyservo]

It does indeed have a daughter card, but the J502 pins are accessable from the top, so J502 it is.  Thank you!