Electro-Voice 1252 - Manual (Page 82)

Electro Industries/GaugeTech
Doc #: E107706 V1.25 5-24
5.22: Five Modes of Time Synchronization
The Nexus meter offers up to five modes of Time Synchronization, depending on options selected at
the time of ordering.
1. Internal Crystal: The Default Time Constant is an Internal Crystal. The crystal is accurate to
approximately 1 minute per month.
2. Line Frequency: The meter ignores the internal crystal and counts frequency to synchronize the
clock. This feature is highly accurate in the presence of reliable system frequency. If power is
lost, the unit automatically switches to the internal crystal.
3. Modbus Commands Time Synchronization: The meter uses Serial Modbus-Based Commands
to change the date and time of the clock. The meter relies upon the Internal Crystal between
synchronization intervals. This mode is used in conjunction with MV90.
4. DNP Line Synchronization: The meter uses DNP Protocol Commands to change the date and
time of the clock. The meter relies upon the Internal Crystal between synchronization intervals.
5. IRIG-B: The meter uses a Signal Generating Device connected to the GPS Satellite System to
synchronize Nexus Time. This mode is accurate to within one millisecond. This mode is
detailed in section 5.23.