2
Description of the safety function STO
16
Festo – GDCP-CMMS-AS-G2-S1-EN – 1306NH – English
A plausibility check is performed in the µP between the relay control for the output stage driver supply
and the monitoring of the driver supply. This serves to provide both error detection of the impulse block
and suppression of the error message E 05-2 (“driver supply undervoltage”) occurring in normal opera-
tion.
Potential-free acknowledgment contact:
Further, the integrated circuit for the “Safe Torque Off ” has a potential-free acknowledgment contact
([X3] pin 5 and 6) for the presence of the driver supply. This is an N/C contact. It must be connected to
an external safety controller or the higher-order controller, for example. Through this controller, the
STO function must be checked regularly (e.g. every 24 hours or at the beginning of the shift, if possible
at every STO request).
If an error occurs in the plausibility check, the control system must prevent further operation, for ex-
ample, by switching off the intermediate circuit voltage or breaking off the output stage enable by the
PLC.
The feedback contact has a single channel and may only be used for monitoring.
Tab. A.7 in Appendix A.1.3 describes the electrical data and runtime performance of the
acknowledgment contact.
When the 24 V supply of the basic unit is switched on and off, the switching status of the
relay can deviate briefly (approx. 100 ms) from the status of the control relay driver sup-
ply Rel [X3.2], due to the difference in speed at which the internal supply voltage starts
up.
Registration of the status of the acknowledgment contact NC1/NC2 is required for every
request of the safety function.
When the safety function has been requested, a change in signal must occur at the ac-
knowledgment contact within an application-specific time. A safety-related reaction must
be initiated in the event of a violation.
Auxiliary supply 24 V, 0 V [X1] and [X3]
The motor controller CMMS-AS-...-G2 makes available one 24 V auxiliary supply each at [X1] and [X3].
This can be employed when using the acknowledgment contact NC1/NC2 or to supply external, active
sensors.
Tab. A.8 Appendix A.1.3 describes the electrical data for the auxiliary supply.
2.2.3
Runtime performance
The runtime performance for typical applications can be found in the sample circuits:
–
Sample circuit for STO in
Section 2.3.
–
Sample circuit for SS1
Section 2.4.