Behavior Of The Cp 440 On Operating Mode Transitions Of The Cpu - Siemens SIMATIC S7-400 Equipment Manual

Startup Characteristics and Operating Mode Transitions of the CP 440

7.3 Behavior of the CP 440 on Operating Mode Transitions of the CPU

Parameter Assignment
Parameter assignment means that the CP 440 receives the module parameters assigned to the
current slot as created with the CP 440: Point-to-Point Communication, Parameter
Assignment programming interface.
Parameter reassignment is performed. The CP 440 is now ready for operation.
7.3 Behavior of the CP 440 on 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 aborted and the
connection is reestablished.
Data traffic at the interface of the CP 440 is continued with the ASCII driver in the case of
parameter assignment without flow control. In other words, the current send request is
completed. Receiving the data depends on the setting of the basic parameter "Reaction to CPU
Stop" (see section "Basic Parameters of the CP 440 (Page 57)").
CPU STARTUP
On start-up, the CP sends the parameters created with the CP 440: Point-to-Point
Communication, Parameter Assignment programming interface. The CP 440 only parameter
reassignment 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 Sending Message Frames
Message frames can be sent only when the CPU status is RUN.
If the CPU goes into STOP during data transmission from the CPU " CP, the 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 communications partner until it has received all data from
the CPU.
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Point-to-point connection CP 440 Installation and Parameter Assignment
Equipment Manual, 03/2022, A5E00057742-AE