The UR Family Communications Guide outlines the Modbus memory map. The map is also viewable in a web browser;
enter the IP address of the L90 in a web browser and click the option.
5.3.6 Real-time clock
SETTINGS PRODUCT SETUP REAL TIME CLOCK
The relay contains a real time clock (RTC) to create time stamps for communications protocols as well as for historical data,
such as event records and oscillography. When the relay restarts, the RTC initializes from an onboard battery-backed
clock, which has the same accuracy as an electronic watch, approximately ±1 minute per month (~23 ppm). Once the RTC
is synchronized with the Precision Time Protocol (PTP), IRIG-B, or SNTP, its accuracy approaches that of the synchronizing
time delivered to the relay. While the RTC is not synchronized via PTP or IRIG-B, or the relay determines that it has an offset
possibly greater than 10 µs from the international time standard, the
activated. When the L30/L90 channel asymmetry function is used, the relay's real time clock must be synchronized to an
external time source using PTP or IRIG-B, typically from a global positioning system (GPS) receiver.
the priority sequence of the time synchronization source, to determine which of the available external time sources to use
for time synchronization. A setting of None causes the RTC and the synchrophasor clock to free-run, and the clock can be
changed from the front panel or from communications protocols. A setting of PP/IRIG-B/PTP/Other, IRIG-B/PP/PTP/Other, or
PP/PTP/IRIG-B/Other causes the relay to track the first source named that is enabled and operational, or free-run if none of
these are available. Here, PP means a time source that is strictly compliant with PP, PTP means a time source that is not
strictly compliant with PP, and Other means any less precise source (SNTP, IEC 103, IEC 104, Modbus, or DNP). When a time
source fails or recovers, the relay automatically transfers synchronization as required by this setting.
When the relay does not have the IEEE 1588 software option and this setting does not display, it uses IRIG-B when enabled
and operational, then failing that SNTP when configured and operational, and otherwise it free-runs unless the clock is
changed from the front panel or from communications protocols.
Setup for IRIG-B is illustrated in the Installation chapter.
For the Other protocols, whenever a time synchronization message is received through any of the active protocols, the L90
clock updates. However, given that IEC 60870-5-103, IEC 60870-5-104, Modbus, and DNP are low-accuracy time
synchronization methods, avoid their use for synchronization when better accuracy time protocols, such as IRIG-B and PTP,
are active in the system. If IRIG-B or PTP is used to update the relay clock, the other protocols (such as SNTP) are not
allowed to update, even if active.
COMMANDS SET DATE AND TIME
REAL TIME CLOCK EVENTS
records the RTC time before the adjustment. A Date/Time Changed event is generated when:
The real time clock changed from SNTP/PTP/IRIG-B and the time difference is more than one second
REAL TIME CLOCK
IRIG-B SIGNAL TYPE:
setting displays when the relay includes the IEEE 1588 software option. The setting configures
menu section of this manual to manually set the RTC.
setting allows changes to the date and/or time to be captured in the event record. The event
Range: None, PP/IRIG-B/PTP/Other, IRIG-B/PP/PTP/
Range: Enabled, Disabled
Range: None, DC Shift, Amplitude Modulated
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
FlexLogic operand is