164 Rockwell Automation Publication 2198-UM005C-EN-P - February 2022
Chapter 9 Kinetix 5300 Safe Torque Off Function
Probability of Dangerous
Failure Per Hour
Safety-related systems are classified as operating in a High-demand/
continuous mode. The SIL value for a High-demand/continuous mode safety-
related system is directly related to the probability of a dangerous failure
occurring per hour (PFH).
PFH calculation is based on the equations from IEC 61508 and show worst-case
values. Table 83
provides data for a 20-year proof test interval and
demonstrates the worst-case effect of various configuration changes on the
data.
Table 83 - Safety Relevant Parameters
Safe Torque Off Connector
Data
The 10-pin connector consists of two parallel 5-pin rows for cascading safety
connections from drive-to-drive when drives are joined by the zero-stack
feature.
Figure 73 - Pin Orientation for 10-pin Safe Torque Off (STO) Connector
Table 84 - Safe Torque Off Connector Pinouts
ATTENTION: Determination of the safety parameters is based on the
assumptions that the system operates in High-demand mode and that to
maintain the integrity of the STO function it must be executed at least once per
year.
Attribute Value
Hardware Fault Tolerance (HFT) 1
Mode of operation High-demand/continuous
STO function components type according to IEC 61508-2 Type A
PFH (1e-9/hour) 0.021
MTTFd 400,000 years
Proof test interval
(1)
(1) No proof test related maintenance is required within 20 years mission time.
20 years
Diagnostic Coverage (DC) 92%
Pin 1
SB+
SB-
S1
SC
S2
Pin 5
STO Pin Description Signal
1/6 Safety bypass plus signal. Connect to both safety inputs to disable the STO function. SB+
2/7 Safety bypass minus signal. Connect to safety common to disable the STO function. SB-
3/8 STO input 1 (SS_IN_CH0). S1
4/9 STO input common (SCOM). SC
5/10 STO input 2 (SS_IN_CH1). S2
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