Siemens Simatic PCS 7 Commissioning Manual page 35

The bus parameters can be set depending on the bus profile.
● Bus parameters that cannot be changed are grayed out.
● Bus parameters are always displayed only as offline values, even if there is an online
The displayed parameters apply to the entire FF subsystem and are briefly explained below.
"System Management Timers" area
FF is a clocked bus system.
Three timers (T1, T2, T3) are integrated in the System Management Information for monitoring
purposes. These timers are used to control the schedule on the FF segment; they ensure that
each FF device has sufficient time for actions and data transmission.
● In PCS 7, by default, timers T1 and T3 operate on the interface module (LAS).
● Timer T2 operates on the FF devices.
Rule: T2 >= T3 + 3*T1
FOUNDATION Fieldbus
Commissioning Manual, 03/2013, A5E03880935-02
connection to the PLC.
Engineering
4.3 Parameter assignment
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