Our customer has a problem on a CB3 robot, that if you stop the robot with a strong force, the CO configured as “System Emergency Stop” are Low after. And this is a big problem, because it stopps another big maschine. Is there a possibility, not to lower this signal, when the robot is stopped by an external force?
It sounds like the robot cannot stop in time due to heavy payload or high speed (or similar), which results in an error instead of a regular protective stop. 
You could try to change the safety settings in the installation. This will, however, also affect how much force is exerted before going into protective stop etc, so you must take that into account.