236 Safe torque off function
An example of a Safe torque off wiring with external +24 V DC power supply is shown
below.
For information on the specifications of the STO input, see chapter Control
connection data (page 186).
Activation switch
In the wiring diagram above (page 235), the activation switch has the designation (K).
This represents a component such as a manually operated switch, an emergency
stop push button switch, or the contacts of a safety relay or safety PLC.
• If a manually operated activation switch is used, the switch must be of a type that
can be locked out to the open position.
• Inputs IN1 and IN2 must open/close within 200 ms of each other.
• A CPTC-02 thermistor protection module can also be used. For more information,
see CPTC-02 ATEX-certified thermistor protection module, Ex II (2) GD
(+L537+Q971) user's manual (3AXD50000030058 [English]).
Cable types and lengths
• Double-shielded twisted-pair cable is recommended.
• Maximum cable length 300 m (984 ft) between activation switch (K) and drive
control board.
Note: A short-circuit in the wiring between the switch and an STO terminal causes a
dangerous fault and therefore it is recommended to use a safety relay (including
wiring diagnostics), or a wiring method (shield grounding, channel separation) which
reduces or eliminates the risk caused by the short-circuit.
Note: The voltage at the INx terminals of each drive must be at least 13 V DC to be
interpreted as “1”. Pulse tolerance of input channels is 1 ms.
2414
2313 Y1
A2
Y2
A1
31
32
Safety relay
Safety PLC
OUT
GND
34
37
35
38
Drive
36 SGND
IN1
IN2
OUT1
OUT2
K
+24 V DC external
power supply
- +
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