Meinberg DCF77 PCI510, Руководство по эксплуатации, Страница: 12 / 22

12
Connectors and LEDs in the rear panel
The rear panel includes the antenna connector, three status LEDs, the BSL button,
and a 9 pin sub D connector (see figure below).
The LEDs let the user check for proper receiver
operation. The upper, red LED is on if the clock is
not synchronous to DCF77. This LED can only
change when the minute changes (seconds incre-
ment from 59 to 0). The brightness of the LED in
the middle depends on the strength of the RF signal.
The lower, green LED should be blinking exactly
once per second corresponding to the time marks
from DCF77. If this LED flickers there is some
electrical noise around which prevents the receiver
from decoding the time marks and synchronizing.
All information given by these LEDs is also availa-
ble via the monitor program.
The BSL button behind the hole in the slot cover
activates the clock's boot strap loader. This mode of
operation is needed if the clock's firmware shall be
updated.
The 9 pin sub D connector is wired to the radio
clock's serial port. Pin assignment can be seen from
the figure beside. This port can
not
be used as serial
port for the computer. Instead, the clock uses the
port to send out Meinberg's standard time string in
order to control an external display or some other
external device. The string is sent out once per
second, once per minute or if requested by an inco-
ming ASCII „?“. It is also possible to change the
radio clock's board time by sending such a string
towards the clock.
Transmission speed, framing, and mode of opera-
tion can be modified using the monitor program.
The string format is described in the section „Tech-
nical Specifications“ at the end of this manual.
antenna
free run
field strength
modulation
BSL key
RxD
TxD
GND