Safety Functions In The Drive; Brief Description; Safe Torque Off (Sto) - Siemens SIMATIC S7-1500 Function Manual

3.11

Safety functions in the drive

3.11.1

Brief description

The safety functions are internal drive functions and are described in detail in the relevant
drive documentation.
The following section describes the reactions to the supported safety functions at the
controller end .
The safety features are only supported for the drive connection via PROFIdrive.
The following safety features are supported by S7-1500 Motion Control:
● Safe Torque Off (STO)
● Safe Stop 1 (SS1)
● Safe Stop 2 (SS2)
The active safety functions can also be evaluated via Safety Info Channel (SIC). Since the
SIC is not a component of S7-1500 Motion Control, you must evaluate it separately in the
user program.
3.11.2

Safe Torque Off (STO)

The Safe Torque Off (STO) safety function is the most common and basic internal safety
function in the drive. STO ensures that no torque generating energy acts on a drive. This
prevents an unintended startup of the controller. The pulses of the drive are eliminated. The
drive is reliably torque-free. This state is monitored internally in the drive.
You can use STO when the drive comes to a standstill in a sufficiently short time due to the
load torque or friction. Other areas of use are where "coasting" of the drive has no relevance
for safety.
Behavior with S7-1500 Motion Control
When STO is triggered in the drive, technology alarm 421 is output, and the technology
object is disabled (alarm reaction: Remove enable).
When the STO signal is no longer present in the drive, you can enable the technology object
again after acknowledgment of the alarm.
S7-1500 Motion Control V13 Update 3
Function Manual, 07/2014, A5E03879256-AC
3.11 Safety functions in the drive
Basics
33