5000/5100 Series Digital Analog Clocks Installation and Operation Manual
25
Chapter 2: ADC-5100 Series Analog Digital Clocks
Secondary Reference Mode
The ADC-5100 Series clocks will run as standard wall clocks when no
input timecode is provided. Rear panel DIP switch SW4 selects the
timebase to be used, either the clock’s internal crystal, or the power line
frequency (50/60Hz).
Rear panel DIP switch SW2 should be switched to the
RUN ON
SECONDARY
position when the clock is used in this mode. When in
this position, the error LED on the clock face will extinguish. Note that
the clock will still function without selecting
RUN ON SECONDARY
.
However, the error LED will flash at the rate of twice per second to
indicate the absence of input timecode.
When operating in this mode, the time must be set manually using the
rear panel set switches,
MANUAL SET
,
CW
, and
CCW
. Once set,
however, the correct time is maintained even in the event of a power
failure. Upon the return of external power, the clock will automatically
self-set to the correct time. The internal battery-backed timekeeping
function will maintain time for up to two years in the absence of
external power.
Auxiliary Offset
DIP switch SW3 allows access to a user-programmed auxiliary offset
from the input timecode’s user bits. The timecode source, however,
must have the ability to generate the correct information in the user bits.
The MTG-3901, CSD-3901/3902, and CSD-5300 Clock System
Drivers are real time timecode sources which can program such an
offset into the timecode’s user bits. The offset is programmed in 30
minute intervals up to 23 hours and 30 minutes, using 6 bits of the
timecode’s user bit space.
The offset is encoded using timecode bits 36, 37, 38, 52, 53, and 54. Bit
36 is the least significant bit (LSB), while bit 54 is the most significant
bit (MSB).
When DIP switch SW3 on the ADC-5100 Series clock is in the
USE
OFFSET
position, the auxiliary offset found in the input timecode’s
user bits is added to the input timecode. The clock hands then display
the total. If no input timecode is available, then DIP switch SW3 has no
effect. If the user bits are incorrectly programmed, then the offset is
disregarded.
