text: <s>[INST] STO during deceleration EDIT: moved to Drives and Motion community -FL I have some servos on K5700 drives. The STO get broke with a light curtain block. This works fine during the move, the servo stops and restarts with an opto, but if the light curtain gets blocked during deceleration the drive keeps going and actually overshoots the target. Has anyone else seen this? There is no brake, but the servo is under load and should want to stop. [/INST] Hello Morley, couple of questions for you: What Kinetix 5700 are you using ERS3 or ERS4 ? Are you using a wired safety signal to the drive or a CIP Safety over EtherneIP ? When you operate an STO on a Servo drive you stop the motor control. So if you request a safety stop action that directly does an STO on the drive , the motor will coast without any control whatever the movement you were doing. This is called a stop category 0. So this is normal that you can overshoot a target since no more control is applied to the motor. With the Mechanical and load inertia the motor can rotate freely for a certain time if you don't have a safety brake. Now you can deploy a different safe stop category. Safe Stop category 1 , called also SS1 . Now the SS1 will give you time to decelerate correctly your axis and stop if before STO occurs. The way of deploying this feature will depend of the answers you will provide on the previous questions. you can also look at this manual : Kinetix 5700 Safe Monitor Functions Safety Reference Manual (rockwellautomation.com) (Link updated) regards \\n </s>