Meinberg DCF77, Operating Instructions Manual

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Overview
The radio clock PEX511 is designed as a „low profile“ board for computers with PCI
Express interface. The data transfer to the computer is done by using a single PCI
Express Lane (x1 board). The radio clock is equipped with a standard height bracket.
For installation in a „low profile“ computer, an adequate bracket can be mounted that
is included in delivery. The I/O signals provided by a D-Sub connector are not
available in this case.
An external ferrit antenna makes the signal from DCF77 available to the on-board
long wave receiver. The demodulated time marks are decoded by the clock´s micro-
processor. If no errors are detected in the current time message an additional plausi-
bility check against the previous time message is performed. If that plausibility
check passes, too, the buffered real time clock on the board is synchronized corre-
sponding to the decoded time and date. Optionally, the decoded date and time
information can be converted to another time zone. The time zone setting can be
modified using the monitor program. The current setting is saved permanently on the
radio clock board.
Software running on the computer can read out the date/time/status and some more
information. Access to the board is made via writing to/reading from I/O ports. It is
possible but not necessary to let the board generate periodic hardware interrupts on
the computer bus.
Pulse outputs
The radio clock PEX511 generates pulses whenever a new second (P_SEC) or a new
minute (P_MIN) begins. The P_SEC pulse is available with TTL level (0/+5V) and
RS-232 level (-3..12V/+3..12V), the P_MIN signal with TTL level only. If required,
DIL switches can be set up to direct each of the pulses to a corresponding pin of the 9
pin connector in the rear panel.