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3Tk2845-.Eb; Table 2-8: Enabling Button, Instantaneous (Simplified Representation) - Siemens 3TK2845 Manual

Safety relays, multifunction device
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Functional Information
3TK2845-.EB.. "Enabling Button"
The 3TK2845-.EB.. has two sensor inputs (S1 enabling button with automatic
start-up, S2 protective door with monitored start-up/automatic start-up), one
cascading input (CAS/OS with automatic start-up) as well as one switching input
(key-operated switch). On the output side there are two relay and two electronic
enabling circuits as well as an electronic signaling output.
Standard operation
In standard operation (key-operated switch "OFF") all enabling circuits are activated. The
cascading input CAS/OS and the protective door input S2 are AND-connected with each
other and affect all enabling circuits at the same time, whereby some are time-delayed.
Input S1 for the enabling button has no function in this context. The opening of the
protective door or a missing signal at the cascading input CAS/OS deactivates all
enabling circuits.
During maintenance (key-operated switch "ON") only two of the four enabling circuits are
activated. In this case, sensor input S2 (e.g. protective door) has no function. The
hazardous area can be entered since the dangerous motion has been switched off via the
two inactive enabling circuits. The dangerous motion can be started again via the
enabling button at sensor input S1 despite the protective door being open.
Safety logic

Table 2-8: Enabling button, instantaneous (simplified representation)

3TK2845 Multifunction Device Manual
GWA 4NEB 926 2087-22 DS 01


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