Siemens SIMATIC CP 440, Руководство пользователя

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Basic Principles of Serial Data Transmission
2-17
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
The figure below illustrates a receive operation with the end criterion “end-of-text
character”.
Waiting for
character
Character
arrived
Message frame buf
fered
End criterion for message frame identified, error entry follows
Character received
with end control
and character delay
time
Error entered in the
STATUS output of
the FB.
Waiting for valid
end code
Message
frame
complete
Error when receiving
Expiration
of the
monitoring
time
Message frame
entered in receive
buffer
Figure 2-6 Sequence of Receive Operation with End Criterion “End-of-Text Character”