Meinberg FDM511 - Manual (Page 16)

16
Areva FDM String
The AREVA string is a sequence of 71 ASCII characters containing the frequency F,
the frequency deviation FD, the time deviation TD, the power line time PLT and the
reference time REF (preceded by the 3 digit day-of-the year), each item seperated by the
characters Carriage-Return (ASCII code 0Dh) and Line-Feed (ASCII code 0Ah). Each
of the five data items is preceded by a fixed 3 digit address (020 ... 024). The string starts
with the STX character (start-of-text, ASCII code 02h) and ends with a terminating ETX
character (end-of-text, ASCII code 03h) on time with the change of the REF time
seconds. The letters displayed in italics are replaced by the calculated values whereas the
other characters are part of the string:
02049.984
021-0.016
022+00.378
02315_03_30.378
024068_15_03_30_
The meaning of the several values is described below:
49.984 The measured power line frequency with a resolution of 1mHz
-0.016 The frequency deviation between calculated and nominal frequency,
with sign character (+/-), resolution: 1mHz, maximum: ±09.999Hz
+00.378 The time deviation between REF time and PL time,
with sign character (+/-), resolution: 1ms, maximum: ±99.999s
15_03_30.378 The power line time, based on the mains frequency,
(hours_minutes_seconds.milliseconds)
Time jumps, like changeover in daylight saving or leap seconds,
will not be executed by the PL time!
068_15_03_30 The reference time from the preconnected clock,
(day-of-the-year_hours_minutes_seconds)
Over Range Condition
Whenever the frequency deviation or the time deviation exceeds its allowable limit
(±9.999Hz or ±99.999 seconds), an over range condition occurs. In this case the
corresponding value is sent out as a sign character (+ or -) followed by 9_ _ _ _ , where
the <_> character represents a space, e.g.: '+9 ' would follow +9.999 when
incremented by 0.001. Furthermore, this condition is indicated bythe Overflow LED.