I believe I am seeing the same problem. I think the new v2 motors are the root cause.
CONFIGURATION:
Code:
#pragma config(Motor, mtr_S1_C1_1, LeftMotor, tmotorTetrix, openLoop, encoder)
#pragma config(Motor, mtr_S1_C1_2, RightMotor, tmotorTetrix, openLoop, reversed)
#pragma config(Motor, mtr_S2_C1_1, FlagMotor, tmotorTetrix, openLoop)
#pragma config(Motor, mtr_S2_C1_2, LiftMotor, tmotorTetrix, openLoop)
Robot is up on blocks. FlagMotor and LiftMotor are DISENGAGED from the gear drives; i.e., no load.
TEST #1:
LeftMotor: v2 Tetrix DC motor
RightMotor: v2 Tetrix DC motor
FlagMotor: ORIGINAL Tetrix DC motor
LiftMotor: v2 Tetrix DC motor
Robot drives just fine, low to max power, forward and reverse. FlagMotor is also fine. No surprises.
However, whenever you run LiftMotor (the third v3 motor in the set) for more than a few seconds, the NXT "loses connection", the downstream servo controllers go ape, and everything freezes, requiring a hard boot of the NXT and usually ROBOTC.
I've tried various changes in pragma (daisy chain, parallel, swapped the controllers...) to no effect. I have not tried swapping the order of the motors in their sequence.
TEST #2:
LeftMotor: v2 Tetrix DC motor
RightMotor: v2 Tetrix DC motor
FlagMotor: Original Tetrix DC motor
LiftMotor:
ORIGINAL Tetrix DC motor
NO CRASH! Everything seems to run just fine with one of the original motors as the fourth motor. In fact, I can run all four motors simultaneously at max power, forward and reverse like a madman.
Now my problem is this: As a rookie team, we were shipped four of the original motors with the plastic gears in our KOP. LEGO Education recently sent us 4 v2 motors as replacements. We have not received our "gear replacement" kits. Our LiftMotor probably cannot be relied on as a plastic gear motor. Should I swap the metal gears from one of our v2 motors into our original plastic gear motors?
WHAT A MESS. We've also been unable to get an encoder to work so we're having to run open loop in autonomous. Advice on that problem is we got a bad encoder. Our first competition is next Saturday and we can't even get past our basic motor usage due to problems created by the exclusive vendor's failure to manage their supply chain. I imagine you guys have been living with this for years but as a rookie coach I find this especially shocking.
I am in a near panic at this point. The team has worked so hard and mechanically our robot is finished. However, we'll be lucky at this point to show up with a robot that does little more than drive.