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Step
Activity in the user program of the PROFINET IO controller
Last - 2
Acknowledge receipt of the last data packet by writing the number of the last data packet to byte 1 of the
"Receive" user data interface.
The optical reader scans byte 1 of the "Receive" user data interface cyclically. As soon as it reads the
number of the last data packet, it writes the value "0" in the bytes 2 and 3 of the user data interface and
also in the byte 1. The end of the current data transfer is signaled to the I/O controller with the value "0" in
byte 1.
Last -1
Scan byte 1 of the "Send" user data interface cyclically. As soon as this byte has the value "0", continue to
the next step.
Last
Acknowledge correct receipt of all data by writing the value "0" to byte 1 of the "Receive" user data inter-
face.
Reaction to disruptions, timeouts and errors
The optical reader performs the following monitoring functions:
● The time between the arrival of two acknowledgments of the I/O controller is monitored
based on the configured value setting in the WBM under "Settings > Communication >
Interfaces > PROFINET IO > Time limit".
● The correct order of the data packets acknowledged by the I/O controller is monitored.
If an error occurs, the optical reader enters the value "B#16#FF" in byte 1 of the "Send" user
data interface, which causes the current data transfer to abort.
We recommend that you monitor the following in the user program of the I/O controller:
● Monitor the time between the arrival of two consecutive data packets.
● Monitor the correct order of the data packets sent by the optical reader.
● Check whether the total length of the user data actually transferred matches the net total
length indicated by the optical reader at the beginning of the data transfer.
If an error occurs, you can abort the current data transfer by writing "B#16#FF" to byte 1 of
the "Receive" user data interface.
9.4.5
FB 79 "VS130-2_CONTROL"
The function block FB 79 for PROFINET IO operations is provided for operating the functions
of the optical reader.
In addition to the SIMATIC S7 system mechanisms for integrating the optical reader into a
PROFINET IO environment, the FB 79 facilitates software integration in control programs.
Note
FB 79 for VS130-2 readers
Note that FB 79 should only be used to connect VS130-2 optical readers for reasons of
compatibility. We recommend the use of the Ident profile for all other readers.
SIMATIC MV500
Operating Instructions, 05/2019, C79000-G8976-C494-02
Process interfacing via an automation system (PLC, PC)
9.4 Control with FB 79
139
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