D13 on the Open4 Base appears to be some kind if light sensor. D14 located in the same plane is unpopulated. I was unable to find any reference for them on the schematics. What are they and how can they be accessed?
It is all about coming up with new ways...to do the same old thing.
I attached the two images of the front and back of the Open4 board. The diode D13 is populated and D14 is not. My first thought is that these are used to sense which card is inserted into the base. You can also look at a previous project EvoPromer Alternative Energy Controller for the images, I wasn't too sure how to get the images inside this post.
D13 and D14 are the Leds of the Open4's embedded RLink (respectively Busy and Run function). You can see the Red one (D13) blinking when you are debugging your application. D14 is unpopulated on the current version due to a production "bug".
They are not available from the target board application.