Safety Properties Overview

General properties	Values
Hardware fault tolerance (IEC 61508)	HFT = 1
Classification element (IEC 61508)	Type B subsystem
Systematic capability	SC = 3
Mission time	TM = 20 Years
Proof test interval	> 20 Years
Safe failure fraction	SFF = 99%
PFH fraction of SIL 3	1.7%
Probability of dangerous failure per hour	PFHd = 1.7E-09 1/h
Mean time to dangerous failure	MTTFD = 55.6 Years
Diagnostic coverage	DCAVG = 99.6%
Common cause failure (see annex F of ISO 13849-1)	CCF: score = 75

Calculation example for safety chain PFH_d:

• Safety PLC that is the FSoE master.
• EtherCAT cabling etc.
• Two drives configured for STO activation over FSoE.

Contribution to the safety chain of the safety PLC: PFH_PLC refer to manufacturer data.
Contribution to the safety chain of using FSoE via EtherCAT cabling etc. is 1.0E-9 1/h.
Contribution to the safety chain of the two drives PFH_d is 2 x 1.7E-9 1/h.

Total value: PFH_d = PFH_PLC + 2 x 1.7E-9 1/h + 1.0E-9 1/h = PFH_PLC + 4.4E-9 1/h

Activation by FSoE

Safety Function	ISO 13849-1	IEC 62061	Maximum Response Time	Comment
STO	PLe, Cat.4	SIL 3	< 10 ms
SS1-t	PLe, Cat.4	SIL 3	< 10 ms	followed by STO*
SS1-r	PLe, Cat.4, SIL 3 or PLd, Cat.3, SIL 2 (limited by the safe encoder)		< 10 ms	followed by STO*
SS2				followed by SOS
SOS, SSM, SSR, SCA, SDI, SLA, SLI, SLP, SLS, SAR

* = configured delay (time to STO) see AXIS#.SAFEPARAM.SS1_#​.TIMETOSTO.

Activation by Safety Functions

Safety Function	ISO 13849-1	IEC 62061	Maximum Response Time	Comment
SBC with one brake	PLd, Cat.3	SIL 2	< 10 ms	Needs to be configured for activation during STO process
SBC with two brakes	PLe, Cat.4	SIL 3	< 10 ms
SDB single channel	PLd, Cat.3	SIL 2	< 10 ms
SDB dual channel	PLe, Cat.4	SIL 3	< 10 ms