Functions
8.2 Time stamping the input signals with IM 153-2
ET 200M
Operating Instructions, 12/2008, EWA-4NEB780600602-08
157
Structure of a special message
A special message always comes from the IM 153-2 (slot 2). It is structured as follows:
Table 8- 7 Structure of a special message
Meaning Number of
bytes
Remarks
Slot number of the
IM 153-2
1 Always "2" in the case of a special message
01h Start-up data (a)
02h Time message frame failure: the following signal messages have,
among others, a precision that is less than 10 ms (b)
03h not used
04h Time difference between message frame and internal clock > 10 ms
(c)
(message always occurs as a message pair)
05h STOP of the time stamping (b)
06h Buffer overflow: the following signal messages are lost until the
buffer is clear again (b)
07h Changeover in the case of redundancy (a)
Code of the special
message
1
08h Loss of information in the case of redundancy (b)
(internal error)
01h (a) BEGIN 00h (a) END
01h (b) INCOMING 00h (b) OUTGOING
(c)
internal time of the
IM 153-2 at the
moment of
synchronization
00h (c)
Synchronization time to which the
internal clock of the IM 153-2 is
set
Property for special
message
1
01h
From the message pair of the special message (c) it can be seen
whether the internal clock has been put back or forward and how
great the time difference was during at the synchronization.
Reserved 1 Unassigned
Time of the special
message
8 (2 DW) Time stamp in ISP-format
(refer to table below for structure)
Structure of a time stamp in the ISP format
A time stamp in the ISP format is structured as follows:
Table 8- 8 Structure of a time stamp in the ISP format
Byte Contents range
0 … 3 Seconds as of 01.01.1900; 0:00:00,000 o´clock in accordance with
01.01.1900 … 06.02.2036
4 … 7 Fractions of a second in multiples of 1/(2
32
) s 0 … < 1 s
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