Siemens SIMATIC NET S7-300 Manual page 196

7 Programming FCs (Functions) and FBs for S7 Ethernet CPs
FC5 AG_SEND / FC50 AG_LSEND - continued
S Case b: Sequence with newer CP types (S7-300 only!)
The send job is started as soon as the parameter ACT = 1 is passed.
In contrast to case a, the protocol used here to transfer the data segments
(each 240 bytes of user data) requires the FC to be called again for each
segment.
Depending on the length of the user data, you must therefore continue to call
the FC with ACT=0 until transfer of the entire data record is indicated; at least
one call with ACT=0 is always necessary. The data is transferred to the
communication partner in segments of 240 bytes.
The status code in the output parameters DONE, ERROR and STATUS is
updated in each block call and can be evaluated.
User program
(CPU cycle)
Supply AG_SEND with
data "X"
ACT = 1
AG_SEND
Job active
Supply AG_SEND
ACT = 0
AG_SEND
Job active
AG_SEND
Job active
AG_SEND
Job active
AG_SEND
Job completed without error
Time
Legend:
1)
Parameter transfer DONE, ERROR, STATUS
A -196
Ethernet CP
1)
Transfer of field 1 active
over Ethernet
1)
Transfer of field 2 active
over Ethernet
1) Transfer of field n -1 active
over Ethernet
1)
Transfer of field n active
over Ethernet
1)
Time
S7-CPs for Industrial Ethernet Configuring and Commissioning
Communications Partner
Data record X is
transferred in
segments.
Time
C79000-G8976-C182-07
Release 01/2007