I have some safety planes setup on PolyScope 3, and that prevents the TCP from crossing the plane, but it does not prevent the robot itself from crossing it. If this plane is a Wall, I should be able to prevent the robot from ever touching the wall, no? Or even coming close to a pinch point?
Restricting the elbow to not pass through a safety plane is only available on e-series robots.
Depending on the movement needs of your robot, you can restrict motion with limits on the joint angles to prevent collisions behind the robot.