What is the purpose of the Rear-End PLC2-M7034-Work area conveyor belt feeding operation timeout error?

Can you explain the steps that should be taken to fix the Rear-End PLC2-M7034-Work area conveyor belt feeding
The solution to the described error requiring attention to sensor X51 on the rear-end PLC2-M7034-Work area conveyor belt feeding operation timeout is to check the condition of the sensor and verify that it is functioning