Application Note for “Usage of AC500 digital standard I/Os in functional safety applications up to PL c (ISO 13849-1)”, V1.0.0
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3 Example
The following example describes the safety analysis and implementation needed for
AC500 digital standard I/O module usage in functional safety applications up to PL c
(ISO 13849-1). In our example, we refer to the AC500/AC500-S setup described in
Figure 5.
3.1 General
We will provide only a safety analysis with the supporting calculation for the Safety
PLC part in the safety loop, which means that values for sensor and actuator parts will
be omitted for simplicity. We aim to reach ~ 15 % of safety loop PFH equivalent for PL
c (ISO 13849-1), as it is shown in Figure 7 [1].
Figure 7. A typical safety loop with Safety PLC [1]
The safe stopping of the woodworking machine with PL c (ISO 13849-1) is discussed
in our example. The presented safety analysis for Safety PLC part can be similarly
applied for other safety functions up to PL c (ISO 13849-1).
3.2 Safety function
The safety function in this example is the actuation of the “Off” switch (see S1 in Figure
5), which leads to SS1 (Safe Stop 1) with a controlled stop of the motor within a maxi-
mum permissible time.
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