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6 Message Frames
6.1.2 Meaning of the characters used in the identification of "free message frames"
Error identifier (character 6)
F (error) =
If a received message frame cannot be processed or contains an error, the
initiating message frame is returned to the sender (production control
computer or PLC) with the identification "F" as 6th character.
otherwise blank (space)
Subgroup identifier (character 7)
Within a session it must be possible to clearly distinguish between the individual message
frames. With the 7th character of the message frame header a session step is defined with
which specific message frames repeatedly occurring within a session are additionally identified.
In this way, the message frame becomes unambiguous within the session.
7th character:
A (Start)
= Start of a session
B (Machining stat.)
= Arrival of a pallet at the machining station
E (end)
= End or temporary end of a session
G (Off)
= Event off
K (On)
= Event on
M (Machine)
= Arrival of a pallet at the machine
otherwise blank (space)
Localization identifier (character 8)
In the case of message frames for specific mode groups, the mode group is defined by means
of the 8th character. If the message frame shall apply to all mode groups, 0 is entered as 8th
character.
When alarms are reported, identification "P" is specified as the 8th character for PLC alarms
or "N" for NC alarms resp.
8th character:
g
= Number of the mode group
(1...8, 0=all mode groups)
N(NC alarms)
= Reporting NC alarms
P(PLC alarms)
= Reporting PLC alarms
A blank (space character) is used as 8th character for message frames for which the allocation
to mode groups makes no sense, such as message frames for connection monitoring
(T_OK____)
6.1.2
Meaning of the characters used in the identifications of
"free message frames"
"Free message frames" are user message frames that do not comply with the System 800
message frame specification, i.e. there is no message frame identification.
The identification bytes of "free message frames" are used in a different manner. They are
used for communications between the interface module and the user interface but are not
transmitted via the link.
6–4
© Siemens AG 1989 All Rights Reserved
06.91
6FC5 197-0AB20-0BP0
SINUMERIK 840/880 (PJ)
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