Pilz PMCprotego S1, Operating Manual, Page: 27 / 99

4-9
4.3 Safety functions
4 Function Description
4.3.1 Safe torque off - STO
Safe฀torque฀off฀-฀STO 4- Sicherheitsfunktion_STO_Ueber_S1
The฀safety฀function฀"Safe฀Torque฀Off"฀(STO)฀removes฀the฀power฀to฀the฀
motor.฀It฀is฀implemented฀via฀the฀servo฀amplifier's฀shutdown฀path฀and฀the฀
safety฀card's฀safe฀outputs.
Features฀of฀the฀safety฀function:

The฀motor฀becomes฀torque-free฀and฀no฀longer฀generates฀any฀hazard-
ous฀movements.

To฀prevent฀the฀drive฀running฀down฀in฀an฀uncontrolled฀manner,฀in฀nor-
mal฀operation฀the฀safety฀function฀STO฀is฀activated฀via฀the฀safety฀func-
tion฀SS1.

STO฀is฀only฀activated฀directly฀when฀
– there฀is฀an฀internal฀error฀on฀the฀servo฀amplifier฀or฀safety฀card
– the฀STO฀delay฀time฀is฀set฀to฀0
– the฀inputs฀"SS1฀Activate"฀and฀"SS1฀SIL3/Reset"฀simultaneously฀
switch฀to฀a฀"0"฀signal฀

The฀STO-ENABLE฀reset฀lock฀on฀the฀servo฀amplifier฀has฀no฀function฀if฀
the฀servo฀amplifier฀contains฀a฀safety฀card.฀The฀output฀contact฀is฀linked฀
internally.฀In฀this฀case,฀the฀safety฀card฀activates฀the฀safe฀pulse฀disa-
bler฀on฀the฀servo฀amplifier฀in฀order฀to฀shut฀down฀the฀power฀element.

The฀safety฀function฀"Safe฀Torque฀Off"฀corresponds฀to฀a฀category 0฀
stop฀(uncontrolled฀stop)฀in฀accordance฀with฀EN 60204-1.
Sicherheitsfunktion_Sxx_Voraussetzung_S1
Prerequisites฀for฀normal฀operation:฀

Input฀"SS1฀Activate"฀and฀"SS1฀SIL3/Reset":฀"1"฀Signal฀(+24฀VDC)

"Ready"฀output:฀"1"฀Signal฀(+24฀VDC).฀The฀safety฀card฀is฀ready฀for฀op-
eration.

"STO฀Acknowledge"฀output:฀“0”฀Signal
Sicherheitsfunktion_Sxx_Voraussetzung_SIL3

To฀achieve฀SIL3฀or฀Ple:฀Connect฀the฀output฀"STO฀SIL3"฀to฀servo฀am-
plifier฀terminal฀X4A/฀3.
Sicherheitsfunktion_STO_Ausloesung
Safety฀function฀is฀activated฀

By฀an฀error฀after฀limit฀values฀have฀been฀exceeded฀or฀

By฀an฀internal฀error฀on฀the฀safety฀card฀or฀servo฀amplifier,฀if฀the฀drive฀
can฀no฀longer฀be฀braked฀safely

By฀executing฀the฀safety฀function฀SS1฀(1/0฀pulse฀edge).฀In฀this฀case฀the฀
drive฀is฀braked฀safely฀before฀it฀is฀switched฀to฀torque-free฀(see฀section:฀
"Safe฀stop฀–฀SS1").
Sicherheitsfunktion_STO_Ausloesung_S1

The฀inputs฀"SS1฀Activate"฀and฀"SS1฀SIL3/Reset"฀simultaneously฀
switch฀to฀a฀"0"฀signal฀

A฀second฀error฀occurs฀while฀SS1฀(drive฀shutdown)฀is฀activated.
Sicherheitsfunktion_STO_Reaktion