Data Exchange S7 Cpu − Ethernet Cp - Siemens S7-300 Configuration Manual

● The user program sends data via a connection using an AG_SEND call at any point, in
● At any point in the CPU cycle, the user program accepts data received via a connection
4.3 Data exchange S7 CPU − Ethernet CP
The Ethernet CP processes the send and receive jobs regardless of the CPU cycle and
requires a certain transfer time. The interface with the program blocks to the user program is
synchronized with an acknowledgement.
2 cases must be distinguished:
● The CPU cycle is faster than the transfer time.
● The CPU cycle is slower than the transfer time.
FC calls faster than the transfer time
If a program block is called again in the user program before the data has been completely
sent or received, the reaction on the interface of the program blocks is as follows:
● AG_SEND / AG_LSEND / AG_SSEND:
● AG_RECV / AG_LRECV:
Configuring and commissioning S7 CPs for Industrial Ethernet
Configuration Manual, 09/2013, C79000-G8976-C182-13
other words event and program-driven.
using an AG_RECV call.
Note
The program blocks can also be called more than once in a cycle for a single
communication connection.
Note
Refer to the flow diagrams for the program blocks in /10/ (Page 230). These diagrams
show how you need to supply and handle the SEND/RECEIVE interface in the user
program for problem-free data exchange.
Consider the following information relating to the CPU cycle and the transfer time as
additional information.
No further job is accepted until the transfer of the data via the connection has been
acknowledged by the Ethernet node. The user program receives the condition code "Job
running" until the Ethernet CP can accept the next job on the same connection.
The job is acknowledged with the condition code " No data yet" if there is no data to be
received on the Ethernet CP. The user program receives this condition code in the CPU
cycle until the Ethernet CP has received the data completely via the connection.
SEND/RECEIVE interface in the user program
4.3 Data exchange S7 CPU − Ethernet CP
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