Configuration file load via NCC is handled together with the host interface running a specific communication protocol. For information on the relating file transfer service, refer to the relevant protocol description. The distribution process after file load is the same as described in the section Load configuration files via the web server of the RTU500 series (page 7-4).
Function Description Release 11 Start-up, Configuration and Time Management RTU500 series Time Management
7.3 RTU500 series Time Management
7.3.1 Time management principle
RTU500 series is managing a distributed system time driven by a common regulated clock. This clock is provided by a CMU dynamically chosen during runtime based on availability and priority.
The time management supports continuous time, in case of time administration master failure or switch over.
7.3.2 Time administration
At startup of an RTU system, the CMUs synchronizes each other with the newest time that is known by any starting or running CMU in the system. This time is used as starting time of the RTU system time until synchronized by a configured time master.
If no CMU was ever synchronized, the absolute time starts with the following value:
Table 7: Absolute time
Every CMU in an RTU system is able to take over the role of a time administration master independent of their rack place, CMU type or redundancy mode.
During startup of an RTU system, one CMU is selected as administration master controlling the system. This CMU is also working as time administration master, whereas all other CMUs are time administration slaves.
If another CMU is getting the administration master, it is also getting the time administration master.
Only one CMU in an RTU system is time administration master.
Figure 16: Time administration master and time administration slave dependencies
Year Month Day Hour Minute Second
1980 01 01 00 00 00
10 kHz TSO
Time Slave
RTU560 Internal Communication TSI
Time Master
Time Message Time
Message
Time Slave
Time Message
Logic Logic Logic
The CMU acting as time administration master synchronizes the RTU time according to the time master configuration provided. The CMU acting as time administration master maintains the time information for the entire RTU. It generates a controlled 10 kHz clock signal and the internal TSO minute pulse.
These signals are needed by all time administration slaves and the I/O master. It then distributes the absolute time information as time message telegrams to time administration slaves and I/O masters.
The time administration slave CMUs are hard-linked to the 10 kHz clock signal and the TSO minute pulse generated by the time administration master CMU. Its own time base is supplied by this 10 kHz signal. Synchronization is based on the TSO minute pulse. Absolute time is provided as time message by the time administration master via RTU System bus to synchronize the time administrations slave´s time accordingly.
Figure 17: Time synchronization in RTU500 series
Deviations between the internal time and the received time on the time
administration master are regulated by scaling pre-divider registers. This method allows a soft regulation of time differences and a long-time correction of crystal clock errors.
If the computed deviation between internal time and the received time is too large, RTU system time is hard synchronized and regulation is restarted.
The regulation works independent from the active time master. That means even in case of a time master switch over the clock is regulated, if the deviation is not too large.
The I/O master (IOM) on every CMU is hard-linked to the 10 kHz clock signal and the TSO minute pulse generated by the time master. It cyclically receives a time message by the MPU via the DPRAM interface and synchronizes its time accordingly.
The IOM again transmits a time synchronization instruction (broadcast) cyclically to all I/O controllers (IOCs) on the I/O boards via the I/O bus (typically every 2 seconds). The IOCs independently regulate deviations between their internal current time and the cyclic time synchronization instructions. Time of all I/O boards is synchronized via the I/O bus with a resolution of ±100 µs and an accuracy of ±0.3 ms.
Function Description Release 11 Start-up, Configuration and Time Management RTU500 series Time Management
7.3.3 Time sources and time masters
The RTU provides a system time that may be synchronized by the following time sources:
Time synchronization by NCC
Time synchronization through a (cyclic) time message from NCC (see section Synchronization by NCC (page Fehler! Verweisquelle konnte nicht gefunden werden.))
Time synchronization by NCC with external minute pulse
Time Synchronization through a cyclic message via a host communication interface and an external minute pulse wired to the TSI (Time
Synchronization Input) of the RTU (see section Synchronization by NCC with external minute pulse (page 7))
(S)NTP server
Synchronization with an (S)NTP server over the network (see section Synchronization via SNTP)
Radio clock
Synchronization according to the GPS, IRIG-B, or DCF 77 standard (only Central Europe) (see section Synchronization via radio clock (page Fehler!
Verweisquelle konnte nicht gefunden werden.))
User entered time via webserver
Time can be entered via RTU web server to set the RTU system time once.
This method is not be configurable and overwrites the priority of configured time masters.
NOTE:
This method is very inaccurate and may only be used for commissioning and setup purposes.
These time sources can be configured to be used by up to eight time masters according to their configured priority. (see section Redundant Time
Synchronization (page Fehler! Verweisquelle konnte nicht gefunden werden.)).
Time masters can be assigned to any CMU in a RTU independent from time administration master.
During start-up, the RTU determines the time masters and their priority by reading the RCD configuration.