Connection Pin
Type
Identifier
Function
X1A.11
#STO-B
Safe torque off, channel B
X1A.12
DIN
#STO-A
Safe torque off, channel A
[X1A]
X1A.22
DOUT
STA
Safe torque off acknowledge
Tab. 8 Inputs and outputs for the STO safety function
STO connection example
The STO safety function (safe torque off) is triggered by an input device that makes the safety request
(e.g. light curtain).
1 Input device for safety request (e.g. light cur-
tain)
2 Safety relay unit
3 Servo drive CMMT-AS
4 Drive axle
Fig. 13 STO sample circuit
Information on the sample circuit
The safety request is passed on through 2 channels over the inputs #STO-A and #STO-B at the connec-
tion [X1A] to the servo drive. This safety request results in the 2-channel switch-off of the driver supply
of the power output stage of the servo drive. Through the STA diagnostic output, the safety relay unit
can monitor whether the safe status has been reached for the STO safety functions.
Installation
23
Festo — CMMT-AS-...-S1 — 2018-02