System Manual HS3A-H21M4
19
Connection of several HS3A in a switch chain
Important!
A HS3A switch chain may contain a maximum of 20 safety switches.
The switches are connected in series using plug connectors and Y-distributors.
If a safety guard 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 guard is open or on which switch a fault has occurred.
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. OA must be connected to IA and OB to IB. If the
connections are interchanged (e.g. OA to IB), the unit will switch to fault state.
Always use input RST 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 DC
must be applied to the RST input for at least 3 seconds. If input RST is not
used in your application, it must be connected to 0 V DC.
Note the following in this aspect:
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 9).
Reset must always be performed simultaneously for all switches of the chain.
Figure 9: Connection example for series connection
GND
24 V DC
Plug /
connector
(male)
1
2
3
4
5
1
HS3A # n
B
1
2
U
B
2
3
O
A
3
4
O
B
4
Y-distributor
M12 plug-connector
(8-pin)
5
O
U
T
5
6
IA
6
7
Socket /
connector
(female)
0
V
7
8
R
S
T
8
1
2
3
4
5
Plug /
connector
(male)
1
2
3
4
5
1
HS3A # n-1
B
1
2
U
B
2
3
O
A
3
4
O
B
4
Y-distributor
M12 plug-connector
(8-pin)
5
O
U
T
5
6
IA
6
7
Socket /
connector
(female)
0
V
7
8
R
S
T
8
1
2
3
4
5
Plug /
connector
(male)
1
2
3
4
5
1
HS3A # 1
B
1
2
U
B
2
3
O
A
3
4
O
B
4
Y-distributor
M12 plug-connector
(8-pin)
5
O
U
T
5
6
IA
6
7
Socket /
connector
(female)
0
V
7
8
R
S
T
8
1
2
3
4
5
1
2
3
4
5
Plug /
connector
(male)
Terminal plug
-K1
-K2
-M1
M
+
-
+
-
S1
