Siemens S7-300 Configuration Manual page 130

Intelligent PROFINET IO device with S7-300 CP
7.4 Programming
Initialization
The CP is configured by the PROFINET IO controller as a PROFINET IO device. For the
configuration, the CP requires the following information in the user program each time it
starts up:
● Length of the input data (with a PNIO_SEND (FC11) call)
● Length of the output data (with a PNIO_RECV (FC12) call)
When the connection between the PROFINET IO controller and the PROFINET IO devices
of a PROFINET IO line is established, the total length of the input and output data is
checked. For each PROFINET IO device, the PROFINET IO controller checks the configured
total length of the input and output data. The total length is compared with the LEN
parameter of the PNIO_SEND and PNIO_RECV program blocks in the user program of the I-
device.
If there is a discrepancy in the length information for the input/output data, the relevant
program block is ended with an error.
During this initialization phase, the two program blocks must be called until PNIO_SEND sets
the DONE parameter to 1 and PNIO_RECV sets the NDR parameter to 1.
Note
Note that successful configuration by the PROFINET IO controller is possible only after local
initialization by the program block calls PNIO_SEND (FC11) for the input data and
PNIO_RECV (FC12) for the output data.
Note
During the initialization, the data of PNIO_SEND (FC11) is not evaluated and the data of
PNIO_RECV (FC12) is set to default values.
The PNIO_SEND and PNIO_RECV program blocks only transfer valid data with the
subsequent calls.
Causes that make reinitialization necessary
Under certain circumstances, the PROFINET IO device demands renewed initialization by
the user program:
● The length information of the input and output areas transferred to the program blocks
does not match the information configured in the PROFINET IO system for this
PROFINET IO device. A change in length in the program block calls in the user program
corresponds to a configuration change.
● The CPU or the CP changes to STOP.
● The watchdog was exceeded (see below).
● Following a connection abort between the PROFINET IO controller and PROFINET IO
device (for example caused by turning off the PROFINET IO controller).
130
Configuring and commissioning S7 CPs for Industrial Ethernet
Configuration Manual, 09/2013, C79000-G8976-C182-13