Siemens SIMATIC ET 200AL - Time Sequence of Synchronization

Functions
5.7 Isochronous mode
PROFINET with STEP 7 V15
200 Function Manual, 12/2017, A5E03444486-AH
Isochronous workflow
When the isochronous mode property of the system is used, the measured value acquisition
is clocked and occurs simultaneously at the various measuring points. The time required for
measurement is reduced. Resultant workflow:
● Continuous machining of the camshaft
● Synchronous measurement of the camshaft positions and gradients within a continuous
rotation.
● Machining of the next camshaft
All camshaft positions and the corresponding measured values (red) are measured
synchronously within a single rotation of the camshaft. This increases machine output and
maintains or enhances precision of the measurement.
5.7.4
Time sequence of synchronization
From reading-in of input data to outputting of output data
The basic time sequence of all components involved in synchronization is explained in the
following:
● Reading-in of input data in isochronous mode
● Transport of input data to the IO controller (CPU) via the PROFINET subnet
● Further processing in the isochronous application of the CPU
● Transport of output data to the outputting IO device via the PROFINET subnet
● Outputting of output data in isochronous mode
T_DC
Data cycle (Time_DataCycle)
T
I
Time for reading in the input data
T
O
Time for outputting the output data
Figure 5-67 Time sequence of synchronization