Monitoring and Response Times of F-Systems
A.3 F-Related Monitoring Times for S7 Distributed Safety
Safety Engineering in SIMATIC S7
A-4
System Manual, 04/2006, A5E00109529-05
A.3.1
Minimum Monitoring Time for F-Cycle Time
Maximum Cycle Time Parameter
The monitoring time for the F-cycle time can be specified in the "Edit F-Runtime Groups"
dialog.
To ensure that monitoring of F-cycle time does not respond when no faults are present
causing the F-CPU to go to STOP mode, the "maximum cycle time" parameter setting must
be greater than the maximum cycle time of the associated OB.
Extending the Maximum Cycle Time Using CiR:
If "Configuration in RUN (CiR)" is used, the maximum cycle time is extended by the lesser of
the following two values:
•
CiR synchronization time of F-CPU
The CiR synchronization time of the F-CPU is the sum of the CiR synchronization times
for all DP master systems that are to be changed simultaneously. The CiR
synchronization time of a DP master system is displayed in
HW Config in the Properties
dialog for the relevant CiR object.
•
Upper limit of CiR synchronization time
The default value for the upper limit is 1 s. You can increase or decrease this value
according to your requirements by calling SFC 104 "CiR".
Additional Information on CiR and Maximum Cycle Time
•
STEP 7 online help: "System Changes during Operation Using CiR"
•
SIMATIC System Software for S7-300/400 System and Standard Functions manual
•
For instructions on determining the maximum cycle time, refer to the manual for the F-
CPU you are using
Determining Runtime of the Safety Program
The runtime of the safety program can be calculated with the aid of an Excel file. The Excel
file is available on the Internet at
http://support.automation.siemens.com/WW/view/en/11669702/133100.
