Festo 572986, Manual, Page: 17 / 42

2 Description of the safety function STO
Festo – GDCP-CMMS-AS-G2-S1-EN – 1306NH – English 17
2.3 Switching example STO – “Safe Torque Off ”
1 2
3
T1
Pilz PNOZ s3
A1
S1
1
S1
2
S2
1
S2
2
S3
4
Y3
2
S1
22
21
A2
11
12
S2
T2
Festo CMMS-AS-...-G2
+2
4
V
0
V
-X9
T1
21 9
DI
N4
DI
N5
-X1
2 3
RE
L
0
V
C2
NC
2
NC
1
-X3
13
14
23
24
T1
PE
In
put
T
3
ac
k
n
o
w
ledg
men
t
T1
13
14
N
L1
24 V DC
0 V DC
Only relevant connections drawn
Out
put
T
3
co
nt
ro
lle
r
e
na
b
le
Out
put
T
3
h
a
rd
w
a
re
en
abl
e
5 6
4
1
Motor controller with safety function
(T2, only relevant connections represented)
2
Safety switching device (T1)
3
Emergency stop switches
4
Inputs and outputs of the higher-order
controller (T3, 24 V)
Fig. 2.3 Circuit diagram, safety function STO
2.3.1 Explanations of the switching example
The switching example shows a combination of the CMMS-AS-...-G2 with a PNOZ s3 safety switching
device from Pilz. A circuit is shown with an emergency stop switch that carries out the safety function
“Safe Torque Off (STO)”. The emergency stop switch (S1) can be replaced by another safety command
device, e.g. safety door switch.
You can find technical data, such as max. current, etc., in the data sheet of the safety switching devices.
Due to the drawn circuitry, a two-channel operation with cross-circuiting recognition is possible. This
permits recognition of:
– earth faults in the start and input circuit.
– short circuits in the input circuit / start circuit.
– cross circuits in the input circuit.
The removal of output stage enable via DIN4 [X1.21] as well as switching off of the driver supply via Rel
[X3.2] results in the motor coasting to a stop.