Siemens NCM S7 Manual page 77

S At various points (event and program-controlled) the user program sends data
on a connection using the AG_SEND call.
S At various points in the CPU cycle, the user program accepts the data received
on the connection using an AG_RECV call.
Note
The blocks can also be called more than once in a cycle for the same
communication connection.
SIMATIC NET NCM S7 for Industrial Ethernet
C79000-G8976-C129–06
SEND/RECEIVE Interface in the User Program
77