Datum bc632D, User Manual

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DIGITAL TIME TRANSMISSION PROTOCOL
Datum Inc bc632D Wall Mount LED Display (Rev A) A-5
A.7.2 MESSAGE FORMATS
There are three possible message formats. A device may be designed to read any or all of them.
A.7.3 DIGITAL TIME - CHARACTER MODE
Digital time is the highest-precision method of transmission. With good local clocks, synchronization to
less than 5 microseconds is easily achieved. A digital time message consists of two messages in this
format:
* <CR> <LF>
Time YY+DDD HH:MM:SS.
::::::
<CR> <LF>
Where:
"*" is an asterisk, which is transmitted as soon after to the on-time mark
as possible. It is followed by a carriage return ($0D) and a line feed
($0A).
There is a space after the word Time, and case is significant.
"YY" is two ASCII numeric characters representing the year, followed by a
space. Numbers from "90" to "99" refer to 1990-1999 and numbers
from "00" to "89" refer to 2000-2089.
"+" is a single character representing the sign of the time. It may be "+"
or " ", representing time greater or equal to zero, or "-" representing
time less than zero. It may be ignored for receiving devices that do
not operate with count down times.
"DDD" is three ASCII numeric characters representing days, followed by a
space. This can range from "000 " to "999."
"HH:" is two ASCII numeric characters representing hours, followed by a
colon. This can range from "00:" to "23:."
"MM:" is two ASCII numeric characters representing minutes, followed by
a colon. This can range from "00:" to "59:."