Safety engineering
Safety functions
Safe torque off
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EDS94AYAF EN 1.0
1.3.2.2 Status information
The safety module transfers information via the status of safety functions with the
SMI_dnState status word.
The SMI_dnIoState status word contains information on the status of the safe inputs and
the safe output. The application in the standard device can evaluate and use the status
words for additional tasks.
1.3.3 Safe torque off
Safe Torque Off/STO
This function corresponds to a "Stop 0" according to EN 60204.
When this function is used, the power supply of the motor is immediately safely
interrupted. The motor cannot create a torque and thus no dangerous movements of the
drive can occur. Additional measures, e.g. mechanical brakes are needed against
movements caused by external force.
The restart behaviour can be set. Function sequence and error response have no adjustable
parameters.
1.3.4 Safe stop 1
Safe Stop 1 / SS1
This function corresponds to a "Stop 1" according to EN 60204.
The function monitors the reaching of the speed n = 0 within an adjustable stopping time.
The speed is calculated from the encoder data (safe speed measurement). Without
encoder the function evaluates the speed status n = 0 from the standard device. For this,
the monitored stopping time parameterised in the safety module must be 0.5 s longer
than the stopping time in the controller.
When the stopping time has elapsed, the power supply of the motor is immediately safely
interrupted (STO). The motor cannot create a torque and thus no dangerous movements
of the drive can occur.
Additional measures, e.g. mechanical brakes are needed against movements caused by
external force. The time for a brake to be applied must be considered when defining the
stopping time.
A restart is only possible after the stopping time has completely elapsed with "SS1 mode
= STO after stopping time". If the SS1 mode parameter is set to "STO at n=0", a restart can
be directly carried out after the transition to the STO status.
Deceleration ramp monitoring can be parameterised. Depending on the parameterised
stopping time, a monitoring ramp is calculated. ( 45)
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