Siemens SIMATIC EMS400S PSB-S Operating Instructions Manual page 42

Data processing plant segment controller – carrier controller
OB1 cycle time
When creating the EMS project, observe the following information to ensure the proper
response of the system:
The longer the OB1 cycle is, the higher the probability that the time available for the data
subframe will be exceeded. If the time slice is exceeded, the PIO of the segment and carrier
controllers will be transmitted in the next data subframe. This procedure delays the reaction
time of the controller by the time it takes to transmit a data subframe.
Recommendation: The maximum OB1 cycle time of 10 ms should not be exceeded with a
minimum SYNC time of 250 ms.
Data processing
Keep in mind that the requirements on the synchronization signal must be observed during
data transmission. See section "PSB-S module (Page 56)".
If the time slice configured for the data subframe is exceeded as a result of data processing,
transmission of the completed data subframe is delayed until the next data subframe.
Transmission is delayed by one synchronization clock cycle, depending on the time
configured. For example, the delay would amount to 250 ms at a time of t
the synchronization signal.
42
SYNC
Operating Instructions, 03/2014, A5E03474166-03
= 250 ms for
PSB modules