External Time Synchronization Via Fieldbus; Internal Time Synchronization Via Rtc - Siemens SICAM Q100 7KG95 Series Manual

11 Time Synchronization

11.4 External Time Synchronization via Fieldbus

In these cases, SICAM Q100 is not external synchronized anymore. The device uses the internal clock (on mil-
liseconds time basis) and the last valid drift. After the programmable time delay, the device reports "Clock Er-
ror", see chapter 14.1.
Switching Back from the Secondary to the Primary NTP Server
While the device is synchronized by the secondary NTP server, it continues to cyclically poll the primary NTP
server. The device will only switch back to the primary NTP server if it receives correct time information and if
none of the criteria for Redundant NTP Servers are fulfilled anymore.
NOTE
Chapter 2 of the system manual SICAM Q100 7KG95xx, order number E50417-C1040-C522, provides infor-
mation on the data format.
11.4 External Time Synchronization via Fieldbus
The external time synchronization via fieldbus is used if the device is connected to the systems control via pro-
tocol Modbus RTU using the RS485 interface.
The time information can also be transmitted from the systems control via Modbus TCP or IEC 61850 using
Ethernet interface. When using the Ethernet connection, Siemens recommend, however, synchronizing the de-
vice from an NTP server, see chapter 11.3.
When using the external time synchronization via fieldbus, the client should send a message containing the
time information to the device in 1-minute cycles.
The time synchronization error using the Modbus RTU protocol is ±20 ms max.
NOTE
Chapter 2 of the system manual SICAM Q100 7KG95xx, order number E50417-C1040-C522, provides infor-
mation on the data format.
11.5

Internal Time Synchronization via RTC

Besides external time synchronization, the internal time synchronization is also possible using the battery-buff-
ered RTC (Real Time Clock). Due to the reduced accuracy, RTC should only be used in case of failure or un-
availability of the external time synchronization.
NOTE
Chapter 2 of the system manual SICAM Q100 7KG95xx, order number E50417-C1040-C522, provides infor-
mation on the data format.
364 SICAM Q100, 7KG95xx, Device Manual
E50417-H1040-C522-A6, Edition 06.2019