EUCHNER CES-I-AR-U-C04 (Unicode) - Manual (Page 16)

Operating Instructions Safety Switch CES-I-AR-U-C04
16
Connection of several CES-I-AR in a switch chain
Important!
Ì An AR switch chain may contain a maximum of 20 safety switches.
Ì In the estimation of the PL for the overall system, a maximum value of 100
years can be assumed for the MTTF
d
according to the limit value in EN ISO
13849-1:2008, section 4.5.2. This corresponds to a minimum value for the
PFH
d
of 2.47x10 -8 /h.
Ì When up to 11 devices are connected in series, these limit values can be
assumed for the entire switch chain as a subsystem. As a subsystem, this
switch chain achieves PL e.
Ì In the case of series connection of more than 11 devices, the PFH
d
can be
calculated according to one of the stated methods in EN ISO 13849-1:2008,
section 4.5.1.
Ì If the simplified method according to section 6.3 of EN ISO 13849:2008-12
is used for validation, the Performance Level (PL) might be reduced when
more than 11 devices are connected in series.
The series connection is shown here based on the example of the version with plug
connectors M12. The switches are connected one behind the other with the aid
of pre-assembled connection cables and Y-distributors. If a safety door is opened
or if a fault occurs on one of the switches, the system shuts down the machine. A
higher level control system cannot, however, detect which safety door is open or
on which switch a fault has occurred with this connection technology. A special AR
evaluation unit is required for this purpose (see section Information on operation
on an AR evaluation unit).
The series connection can also be realized via additional terminals in a control
cabinet.
The safety outputs are permanently assigned to the respective safety inputs of the
downstream switch. FO1A must be routed to FI1A and FO1B to FI1B. If the connec-
tions are interchanged (e.g. FO1A to FI1B), the unit will switch to the fault state)
Always use the RST input in series connections. All switches in a chain can be
reset at the same time with this reset input. To do this, a voltage of 24 V must be
applied to the RST input for at least 3 seconds. If input RST is not used in your
application, it should be connected to 0 V.
Note the following on this aspect:
Ì A common signal must be used for all switches in the chain. This can be a
changeover switch or the output of a control system. A button is not suitable
because Reset must always be connected to GND during operation (see switch
S1 in Figure 5).
Ì Reset must always be performed simultaneously for all switches of the chain.
Information on operation on an AR evaluation unit
The devices can be operated on an AR evaluation unit. Please refer to the operating
instructions for the relevant AR evaluation unit for more information.