Overview c28com, Installation – Meinberg C28COM User Manual
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Overview C28COM
The radio remote clock C28COM is designed to operate in conjunction with a serial
RS-232 interface of a computer. The supply voltage for the module is provided by
control signals of the COM port. Therefore no external voltage needs to be applied.
The module generates a serial Meinberg Standard String which contains informations
like date, time and status of the clock. C28COM sends this string once per second with
transmission speed 9600bd framing 7E2, see chapter „Format of the Meinberg stan-
dard time string“ for details.
An internal ferrit antenna is used to receive the signal from DCF77 and supplies it to
the on-board LF receiver where it is demodulated by a straight detector with automatic
gain control. The demodulated time marks are fed to the clock´s microprocessor for
decoding. Parity and consistency checks over a period of two minutes take care for
detecting errors in the received time telegram. The checked and decoded time is
written to the software clock and spread by the serial interface of C28COM.
C28COM includes a two-color LED which displays the demodulated DCF77 time
marks and the status of the clock.
The clock is precanned with a connection cable of two meters length and is equipped
with a 9pin D-SUB female connector (25pin on request). It is appropriated to connect
directly to the RS-232 port of a PC.
The scope of supply includes a driver software for Windows95/98
®
operating
systems. This program adjusts the system time of the computer and displays several
status information of the time adjustment and the clock C28COM.
Meinberg driver software for various different operating system can be found for
free download at:
Note about using the driver software: the module C28COM doesn’t
include a real time clock. After power up the time string can’t
contain the current time until first synchronization therefore. If you
are using a Meinberg driver software, the option of accepting the
time send by the DCF-clock even in case of free run should not be
active.