Diagnostic Block "Cpu_Rt - Siemens SIMATIC PCS 7 Operating Manual

Configuring the safety program
7.11 Monitoring times and system response times
● min. F-specific monitoring times
This sheet contains formulae for calculating minimum values:
– MAX_CYC
– PROFIsafe monitoring time
– TIMEOUT between F-shutdown groups
– TIMEOUT between F-CPUs
● Max. response times
You can use this to determine the maximum runtime of a signal from an input to an output
in the system, with various types of configuration taken into account.
● Typ. Response times
A wizard for estimating the typical response time
7.11.1

Diagnostic block "CPU_RT"

Diagnostic block "CPU_RT"
In PCS 7 V7.0 and above the "CPU_RT" diagnostic block is inserted with "Generate module
drivers" in the @CPU_RT chart. Channel/diagnostic blocks in PCS 7 Library V7.0 and above
must be used for this.
The "CPU_RT" diagnostic block implements a new controller and cycle behavior in the
overload range. When there is a cycle overload in the CPU, the time intervals between two
calls of the interrupt OBs are increased (the number of calls are reduced). In the safety
program, this may cause I/O modules to be passivated or an F-STOP to be triggered,
depending on the setting of the subsequently calculated monitoring times. To avoid this, the
cyclic interrupt OB with security program must be disabled to reduce the calls. To do this, set
the OBxx_ATT input (xx = no. of the cyclic interrupt OB with safety program) at the CPU_RT
block to "0".
134
Maximum time between 2 calls of the cyclic interrupt OB with F-program
Maximum time between 2 frames from the master to the F-I/O.
Timeout value for fail-safe communication between F-shutdown groups in an F-CPU
Timeout value for fail-safe communication between two F-CPUs
Compendium Part B - Process Safety (V8.2)
Operating Manual, 07/2016, A5E35031794-AB