PID Questions

[StrMNX]

Hello, So i'm trying to understand PID in the off-season before 2017. For the most part things have been normal and fully working but i do have some questions on certain things. Any assistance would be greatly appreciated

1. How would you handle an output to multiple motors? i know for 2 motors most teams would use a "y" cable, but what would you do if you had to control 3 motors (such as a 6 cim drive-train)? is there any example code on how to do so?

2. I've studied up on the methods of tuning (Ziegler-Nichols) and i'm aware of how to properly tune the loop, but what are your starting value for the constants? like people say "increase P Gain until it oscillates", but what is a good starting point for the P Gain, I Gain, and D Gain?

Thank you for your time