Schiffsuhrensysteme Marine Time Systems

Master Clock Systems
Master Clock Systems
SIEMENS SIMOS MMC 71
Technical Description
The marine master clock system SIMOS MMC 71 provides the accurate time and date for
the connected systems. Further outputs can control analogue and digital slave clocks, ship’s
data-logging and monitoring systems. The MMC 71 is build from modules of the Siemens
PLC family SIMATIC S7. This is a guarantee of high availability and reliability. The S7 is time
controlled by the real-time hardware clock of the CPU.
Smart slave clocks with four-wire technology can be connected by the interface RS 485.
For the connection of other subsystems the MMC 71 provides serial interfaces with
the TTY, RS232 or RS422 physics. It is also possible to control smart slave clocks with twowire
technology.
With the integrated Siemens MPI-interface the MMC can communicate to other Siemens
marine automation equipment.
The MMC can be synchronized from the operating panel or via an optional external contact
(e.g. from the radio room).
An serial interface (TTY, RS232 or RS422) from a GPS receiver may be used to update and
synchronize the UTC (universal time coordinated) or the LT (local time) of the master clock.
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