4 SEND/RECEIVE Interface in the User Program
A-96
S7-CPs for Industrial Ethernet Configuring and Commissioning
Release 01/2007
C79000-G8976-C182-07
FC Calls Slower than the Transmission Time
If a block is called again before the data were completely transferred or received,
the procedure is as follows on the interface of the FC blocks:
AG_SEND/AG_LSEND:
The job is positively acknowledged. The Ethernet CP is ready to receive a new
send job (at the earliest however with the next call).
AG_RECV/AG_LRECV:
The job is acknowledged with “New Data Received” when the data have been
transferred to the user program. Following this, the FC call can be repeated.
Notice
Remember that resource shortages can occur if the processing speeds on the
sender and receiver are not the same (sender faster than receiver).
The sender receives a message from the FCs if problems occur (“No resources on
the destination station”).
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