I finally figured out something that works. coder.opaque was not the answer, or if it was I could not get it working. This is probaly somewhat of a hack, but it works. So the really cool part about setting up a device driver block is that it allows you to copy paste cpp code straight from an example arduino sketch and use it, however I couldn't find any way for the device driver block to output a global array that I had defined in my driver cpp file.
The solution was to use a stateflow chart instead. All I had to do was make a structure that had my array in it in my global array in my driver .h file and then include that header file in the configuration paramters -> simulation Target -> header file.
Then I could drop in a stateflow chart that just outputs the array. This example was very helpful.