Industrial automation systems consisting of several distributed controllers need a precise synchronization for commands, events and process data.
For instance, motors for newspaper printing are synchronized within some 5 microseconds to ensure that the color pixels in the different cylinders come within 0.1 mm at a paper speed of some 20 m/s.
Similar requirements exist in high-power semiconductors (e.g. for converting between AC and DC grids) and in drive-by-wire vehicles (e.g. cars with no mechanical steering wheel).
The PTP Industrial Profile (PIP) is a standard of the IEC 62439-3 [1] that specifies in its Annex C two Precision Time Protocol IEEE 1588 / IEC 61588 profiles, L3E2E and L2P2P, to synchronize network clocks with an accuracy of 1 μs and provide fault-tolerance against clock failures.
[2] The IEC 62439-3 PTP profiles can be used to ensure deterministic operation of critical functions in the automation system itself, for instance precise starting of tasks, resource reservation and deadline supervision.