Siemens SIMATIC S5-115U, User Manual

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S5-115U Manual Communications Capabilities
Sending/Receiving with the 3964/3964R Line Procedure in Detail
Connection Buildup
The 3964(R) line procedure executes the following steps automatically.
Trans-
mitter Receiver
When there is no Send order to process, the 3964(R)
driver waits for the peer in the link to establish a
connection.
STX is a control character (02
H
) which initiates
connection buildup.
STX
Possible Responses from the Receiver Response (from the Transmitter's Point of View)
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
Receiver acknowledges with DLE (10
H
) prior
to time-out (QVZ).
Connection buildup was successful; the trans-
mitter sends the first character from the send
buffer.
(QVZ: Word 5 in the parameter list)
Receiver acknowledges with a character
other than DLE or STX prior to time-out
(QVZ)
or
receiver does not acknowledge prior to
time-out Connection buildup was initially unsuccessful;
the transmitter makes another attempt to
establish a connection. (Number of attempts to
establish a connection: Word 7 in the parameter
list). If the last attempt also proves unsuccessful,
the transmitter enters a code in the Send coordi-
nation byte (CBS).
Receiver transmits an STX control character
prior to time-out (QVZ) Initiation conflict, i.e. both peers in the link want
to transmit. The peer with the lower priority
sends DLE, thus enabling the higher-priority
node to transmit first; the lower-priority node
then transmits its data. The two peers must never
have the same priority!
(Priority: Word 3 in the parameter set)
EWA 4NEB 811 6130-02b
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