Error in Inventor's Guide?
 

I have Vex Robotics Kit. I built a 4WD skid-steer robot like the Tumbler-Bot on the web site at http://www.vexlabs.com/vex-triplets.shtml Each wheel has its own motor. I tried to follow the instructions on page E-9 but one wheel won't work if the motors are connected to motor ports 2, 3, 7, and 8. If I connect the motors to ports 1, 2, 7, and 8, all wheels work BUT when I want to turn the robot left, the robot turns right, and when I want to turn the robot right, the robot turns left. Please check into this.

Re: Error in Inventor's Guide?
 

One thing you may want to check: Did you put a jumper in Port 15 (for tank/"23" mode), or Port 16 (for arcade/"12" mode)? Refer to page 7.17 in the guide.

Re: Error in Inventor's Guide?
 

I put a jumper on Port 16.

Re: Error in Inventor's Guide?
 

Did you buy a fourth motor from Vex, or are you using only the ones from the kit? The standard kit only comes with three continuous rotation motors, and one limited rotation servo. This is probably what is making the fourth wheel not fully rotate 360 degrees.

Re: Error in Inventor's Guide?
 

After buying the Vex Robotics Kit and using it for a while, I bought another motor, another servo, wheel kit, gear kit, bumper switch kit, limit switch kit, and metal and hardware kit. I used four motors and four large wheels. The transmitter is set for "12" drive.