Siemens SIMATIC KP8 - Fail-Safe Mode

Technical specifications
9.4 Fail-safe mode
KP8, KP8F, KP32F
Operating Instructions, 11/2011, A5E03284305-02
109
9.4 Fail-safe mode
KP8F and KP32F internally
The block diagram:
,QSXWXQLW &RQWUROOHU %ODFNFKDQQHO,QSXW
2XWSXW
3RZHUVXSSO\
The relevant values of the individual blocks are shown in the following.
Note
All values for the following data are based on the SN 29500:2005 and an ambient
temperature of 60 °C.
Input unit – 1oo1 mode
Parameter Value Comment
Hardware Fault Tolerance 0 –
Classification A –
Architecture 1oo1D –
Failure mode
• Detected
• Undetected
Dangerous process value
• 5.50 FIT
• 0.34 FIT
Due to failures in the input circuit
Failure Mode Diagnostic
• Detected
• Undetected
No error signaling or no safe
values
• 0 FIT
• 0 FIT
Calculation according
IEC 13849-1, CAT4
Diagnostic Coverage 94.15 % –
Diagnostic test interval 15 ms Errors detected in each firmware cycle
Safe Failure Fraction 99.19 % –