Connection Of Several Safety Switches In A Cascade - SICK TR4 Instrucciones De Servicio

Operating Instructions
TR4
WARNING
8014467/YIJ2/2015-03-02
Subject to change without notice
Electrical installation
5.3.4

Connection of several safety switches in a cascade

Several safety switches with cable (TR4-S....P) or an 8-pin M12 connec-
tion plug (TR4-S..01C) can be cascaded (connected in series). The num-
ber of safety switches in a cascade is almost unlimited. However it will
have an effect on the response time of the system (see section 9.1.2
"Response time for multiple cascaded TR4 safety switches" on
page 91). It is therefore recommended not to use more than 30 safety
switches in a cascade.
Use external device monitoring!
The TR4 has no external device monitoring. To achieve SIL3/PL e you
must therefore implement external device monitoring with the aid of
suitable higher level safety evaluation.
The actual performance level or safety integrity level achieved depends
on the external circuit, the design of the wiring, the selection of the con-
trol switch and its placement on the machine.
Evaluate both safety outputs!
To ensure safety it is imperative you evaluate both safety outputs
(Out A and Out B) (see Fig. 7).
Prevent tampering!
On the usage of TJplug connectors for cascading you must mount the
connecting cables such that simple bypassing of the safety switch is
not possible.
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Chapter 5
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