Technical data

Installation & Operation Manual GM-TTT

Page 60

5 Operation with a Real Time Reference

5.1 Connection of an External Reference

The standard GM-TTT version uses an external reference, for example with a DCF77 or GPS

receiver. At REF.DATA IN, GM-TTT expects to receive a serial data protocol with time, date

and status data, as well as a seconds pulse (1pps signal). The data string has to be automa-

tically sent every second. The data transfer should start shortly after the reference edge of the

seconds pulse and be completed 220 ms after the reference edge at the latest. The data must

refer to this seconds pulse.

• The data transfer format is: 2400/7/E/2.

• The data string consists of 32 ASCII characters:

STX Start of Text $02

D: followed by the date Day.Month.Year

T: followed by the day of the

week

1-7, 1 = Monday (0 = day of the week is not known).

U: followed by the time Hours.Minutes.Seconds

# synchronisation after power-on

# = Invalid time, clock is not set since power-on.

‘ ‘ = Clock is set.

* current synchronisation * = Clock in free-run.

‘ ‘ = in-sync (“lock“).

S time zone S = CEST

‘ ‘ = CET

U = UTC

! announcement ! = Announcement of start/end of DST.

A = Announcement of a leap second.

‘ ‘ = No announcement.

ETX End of Text $03