Pilz PSSnet SHL 8T MRP - Manual (Page 97)

Synchronizing the system time in the
network
98
7.3 Precision Time Protocol
PSSnet SHL - Basic Configuration
Pilz GmbH & Co. KG, Felix- Wankel Str. 2, 73760 Ostfildern
X Cable delays; device delays The communication protocol specified by
IEEE 1588 enables delays to be determined. Formulas for calculating the
current time eliminate delays.
X Accuracy of local clocks The communication protocol specified by IEEE
1588 takes into account the inaccuracy of local clocks in relation to the
reference clock. Calculation formulas permit the synchronization of the lo-
cal time, taking into account the inaccuracy of the local clock in relation to
the reference clock.
PTPv1
Stratum
number PTPv2
Clock class Specification
0 – (priority 1 =
0) For temporary, special purposes, in order to assign a higher
accuracy to one clock than to all other clocks in the network.
1 6 Indicates the reference clock with the highest degree of
accuracy. The clock can be both a boundary clock and an
ordinary clock. Stratum
1/ clock class 6 clocks include GPS
clocks and calibrated atomic clocks. A stratum 1 clock cannot be
synchronized using the PTP from another clock in the
PTP
system.
2 Indicates the second-choice reference clock.
3 187 Indicates the reference clock that can be synchronized via an
external connection.
4 248 Indicates the reference clock that cannot be synchronized via an
external connection. This is the standard setting for boundary
clocks.
5–254 – Reserved.
255 255 Such a clock should never be used as the best master clock.
Table 6: Stratum – classifying the clocks