General; Safety Function Request; Acknowledgement Methods - ABB FSO-21 User Manual

48 Safety functions

General



Safety function request

A safety function can be activated locally from FSO digital inputs, from a safety PLC,
in FSO internal fault situations or by another safety function (see section
Dependencies between safety functions
If you want to control a safety function with a push button, connect an activation
button to an FSO digital input. 24 V in the input is the standby (negative) state and
0 V is the positive (request) state.
Button pressed
A
B
ID Description
A Normal request: The request is recognized when the button is pressed. The pressing
time of the button must be at least 20 ms.
Note: The safety function request must be removed before the acknowledgement is
accepted.
B Short low signals (less than 20 ms) are ignored.


Acknowledgement methods

You can configure the acknowledgement method separately for the start-up, STO
(SSE and SS1 always end in drive STO), SLS, SDI and POUS safety functions.
The acknowledgement method can be manual or automatic, from a safety PLC via
the PROFIsafe communication bus, or either manual or from a safety PLC.
• Automatic: The FSO module acknowledges the start-up and/or safety functions
automatically when this has completed successfully and the safety function
request has been removed.
• From a safety PLC: The FSO module expects an external acknowledgement
signal from a safety PLC via the PROFIsafe communication bus. The PROFIsafe
profiles include the acknowledgement bits (see section
on page 166).
• Manual: You must connect an acknowledgement button to the FSO module. The
user must push the button to acknowledge the start-up and/or safety functions.
on page 158).
Button release allowed
20 ms
FSO PROFIsafe profiles
Time