Cyclic Interrupt Ob; Cyclic Interrupt Ob - Cycle Time And Phase - Siemens SIMATIC S7-1500 Getting Started

Software section
3.2 Creating the program
3.2.4

Cyclic interrupt OB

3.2.4.1 Cyclic interrupt OB – Cycle time and phase
Cycle time and phase offset can be changed
Main [OB35] is located below the program blocks inserted into the project. Main [OB35] is a
cyclic interrupt organization block (cyclic interrupt OB). Cyclic interrupt OBs serve to start
programs in periodic time intervals independently of the cyclic program execution. The start
times of a cyclic interrupt OB are specified using the cycle time and the phase offset.
Cycle time
The cycle time determines the interval at which an OB is called. The cyclic interrupt OB has
a cycle time of 100000 μs by default.
Phase offset
The phase offset is used to increase the accuracy of the processing intervals of cyclic
interrupt programs. If an OB has the same or a common multiple clock pulse of another OB,
both can be operated at a precise interval by a phase offset.
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Getting Started, 05/2014, A5E03981761-AC
S7-1500