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10.3
Synchronisation of several devices
For synchronization of the SIMEAS Q80 7KG8080 units, the device has a BNC socket labeled SYNC. Depending on
the configuration, an external synchronization signal (DCF77, GPS, IRIG-B or NTP) can be received or used to
synchronize several devices with each other.
Technical specification of the synchronization.
DCF77
The DCF77 signal is applied via the BNC socket SYNC. SIMEAS Q80 7KG8080 processes a LOW active 5 V TTL
signal: 1 Hz pulse:
Duration of synchronization: The complete time is encoded within one minute and begins at the start of the next
minute.
For this reason the minimum duration for the synchronization process is at least one minute!
GPS
The GPS receiver is connected at the 9-pin DSUB terminal "GPS". The supply is provided via SIMEAS Q80
7KG8080. In this way, the GPS receiver finds its positions as soon as the device is activated.
Duration of synchronization process: The minimum duration for synchronization depends on the reception and
on the last location of use. Upon first use, the receiver needs a few minutes until multiple satellites and its own
position have been located. Upon the next start, the last position data are usd, and the satellites are found found
more quickly.
With a direct line of sight to the sky, the receiver is typically synchronized within one minute.
NTP Network Time Protocol
The Network Time Protocol (NTP) is a standard for synchronizing clocks in computer systems and uses the
connectionless transport protocol UDP. It was specially developed to enable reliable timing via networks having
variable package runtimes.
Precision: NTPv4 can keep a local system's time via the public Internet at a precision of 10 milliseconds; in local
networks under ideal conditions, precision levels of 200 microseconds and even better are possible.
Duration of synchronization process: Synchronization on an NTP server is a lengthy process. At intervals of 64
seconds, SIMEAS Q80 7KG8080 exchanges a data package with the server. Initially, 4 x64s are needed to set the
clock, after which the clock is synchronized at 64s intervals. It can take up to 3 h to reach precision in the range of
20ms. In order for the synchronization to begin upon activation, the measurement device must be set to use NTP
by default.
SIMEAS Q80 7KG8080 supports up to two NTP servers. For setting NTP, the following parameters are needed:
· selection of the time zone
· observance of the daylight saving's time transitions
· IP of the NTP server (1)
· IP of the NTP server (2)
Note
DCF77 TTL signal with inverted logic (Low active)
The synchronization between devices synchronized with NTP (see
Separate synchronization of all devices.
However, it is not possible to determine it.
If the phasing between two voltages in different devices is to be compared, only the Master is
to be synchronized to NTP. This synchronizes additional devices via DCF77, see
LAN in Master/Slave setup
Connections and Conditioning
) is within approx. 10ms in the best cases.
40
.
39
Power Quality Recorder SIMEAS Q80 7KG8080, Operating instruction
NTP time via LAN under
NTP time via
E50417-B1074-C419-A1, Release 07.05.2010
E-37
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