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Entry type: FAQ Entry ID: 40924020, Entry date: 04/19/2010

How do you implement an Emergency Stop for stop categories 0 and 1?

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The F Systems library does not contain the Emergency Stop block for stop categories 0 and 1. However, this can be created from separate blocks of the Fail Safe library. Fig. 01 shows such a configuration for stop category 1.

Fig. 01: Emergency Stop for stop category 1

In the case of a stop category 1 emergency stop, the "Stop1" emergency stop button is connected via channel driver block "F_CH_DI". This is directed to an AND operation "F_AND4" to which other input drivers can be connected. The RS flip-flop "F_RS_FF" is reset via the negated output of the AND operation.
The acknowledge signal "Quit" is also read in with a channel driver block "F_CH_DI" and interconnected via an edge evaluation "F_R_TRIG" to the set input of the RS flip-flop. The Reset input has priority.
The output signal of the flip-flop is interconnected to the timer block "F_TOF" that switches off the signal with a time delay. The output signal of the time is now directed to another AND operation "F_AND4" to which operational switching can also be connected. The output is interconnected to the output driver "F_CH_DO". These then control the two emergency stop contactors K1 and K2.

The configuration and function are comparable in the case of a stop category 0 emergency stop. Only there is no timer block "F_TOF", so that the output of the flip-flop is wired directly to the "F_AND4" block.

In order to ensure error-free operation of the fail-safe blocks, it is essential to have correct and complete connection of the blocks. More information on this is available in the programming and operating manual "SIMATIC Industrial Software, S7 F/FH Systems - Configuring and Programming" in Entry ID 2201072.

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