Behavior Of The Cp 440 During Operating Mode Transitions Of The Cpu - Siemens SIMATIC CP 440 Manual

7.3 Behavior of the CP 440 During Operating Mode Transitions of
the CPU
Once the CP 440 has been started up, all the data is exchanged between the CPU
and the CP 440 via the function blocks.
CPU STOP
In CPU-STOP mode, communication via the S7 backplane bus is not possible. Any
active CP-CPU data transmission, including both send and receive message
frames, is terminated and the connection is reestablished.
With the ASCII driver and parameterization without flow control, data traffic at the
CP 440 interface is continued. In other words, the current send job is completed.
Receiving the data depends on the setting of the basic parameter "Reaction to
CPU Stop" (see Section 5.3.1).
CPU STARTUP
During startup the CPU sends the parameters created with the CP 440:
Point-to-Point Communication, Parameter Assignment parameterization interface.
The CP 440 only carries out reparameterization if the parameters have changed.
CPU RUN
When the CPU is in RUN mode, sending and receiving are unrestricted. In the first
FB cycles following the CPU restart, the CP 440 and the corresponding FBs are
synchronized. No new FB is executed until this is finished.
Points to Note When Receiving Frames
You can only send message frames in CPU RUN.
If the CPU goes into STOP during data transmission from the CPU
SEND_440 FB reports after restart that the current program has been interrupted
and the job has been terminated due to BREAK/restart/reset.
Note
The CP 440 does not send data to the communication partner until it has received
all the data from the CPU.
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
Startup Characteristics and Operating Mode Transitions of the CP 440
CP, the
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