Hi LabVIEWEnthusiast,
1. I don't know off the top of my head what the number is but you can always go to NI Measurement & Automation Explorer and expand the Remote Systems category on the left. If you click on your cRIO and then select the System Settings tab at the bottom of the window, you'll see how much disc space is currently being used on your cRIO.
2. The number of times the code iterates will depend on what's in it. The loop in RobotMain.vi is your main loop. During each iteration of the loop, we communicate with the driver station to determine what mode we're in and update any values coming from or going to the driver station. Then we go to the case structure we'll execute whichever mode (teleop, auto, etc) we're currently in. Then, we move onto the next iteration of the loop where we check with the driver station and then execute the code for the appropriate mode we're in. Even if no new values are received from the driver station, we still exectute the code of whichever mode we're in. Now lets say, for whatever reason, you've placed a 2 second wait inside your Teleop VI. Each time we iterate through the while loop and we're in Teleop mode, it'll take 2 seconds plus the time it takes to execute the rest of the code in Teleop.vi before it goes onto the next interation of the while loop.
3. This is going to be a very high level response, so please let me know if you want something a little bit more specific. You can look at the cRIO as having two parts: the FPGA and the Real Time OS. The FPGA is mostly responsible for reading data from and writing data to the I/O modules in the cRIO and we have written the code for this. We have hidden this code from you and the students. Everything you program is deployed to the Real Time OS on the cRIO and you do not affect the FPGA at all.
4. In general, closing references is good programming practice. Every reference is additional memory that is allocated. When you close a reference, you're freeing that memory for other parts of your program to use. If you don't close your references, you end up with a memory leak because every time you run your VI, more memory is allocated when you open a reference. If you look at RobotMain.vi, you'll notice three sections: Begin, Teleop/Auto, Finish. In Begin is where you open your references. In Teleop/Auto, you use those reference to communicate with various parts of your code. In Finish, you close all your refences because you're no longer using them. This follows the good programming practice of Open, Read/Write, Close.
The examples do make this concept a little confusing. This is because the examples were created to run on their own and you had to break them up to incorporate them into the main robot code. Lets say you wanted to use the Simple Digital Input Example in your robot code. You would place the DIO Input Open VI in Begin VI. DIO Input Get Value would go in Teleop. Finally, DIO Input Close would go in Finish.
I hope my answers helped.
~Olivia
