Step 8: Programming The Emergency Stop Function - Siemens SIMATIC S7 Functional Safety Manual

Getting started
2.3 Programming
2.3.5

Step 8: Programming the emergency stop function

In this step, you program the emergency stop function for this example.
Used for emergencies only, the emergency stop button is a safety measure to immediately
shut down all machine functions. An emergency stop button must be highly visible in color
and shape and must be easy to operate in emergency situations. In this example, the
emergency stop is a manual push button attached next to the safety door entrance to the
service area enclosure. The emergency stop function provides shutdown in the case of an
emergency stop, an open safety door, or someone entering the protected area monitored by
the laser scanner.
Click the "Play" button to start the animation file. Click the other control elements to rewind,
pause, go back, or go forward.
Procedure
1. In the interface of the "Safety_Interlock" F-FB, create a static tag of data type "Bool"
named "EN_Safety" (Enable safety circuit).
Note
If the emergency stop is off, the safety door is closed, and the protected area laser
scanner is not triggered, the inputs from the emergency stop, safety door, and the laser
scanner are all true. All three inputs must be true, before the ESTOP1 instruction can
power "EN_Safety". When "EN_Safety" is true, then the user knows that his operation is
back to normal and that he can startup safely.
2. Insert a new network.
3. Insert the "AND logic operation" instruction from the "Bit logic operations" subfolder of the
"Instructions" task card.
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S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA