QUESTION:
In S7 communication on the S7-400 with the "BSEND" (SFB12) and
"BRCV" (SFB13) blocks, is the send job repeated automatically on
the system side when the "BRCV" block (SFB13) is in the "disabled"
state ("EN_R = 0")?
ANSWER:
If the send job has been started on "BSEND" block and the
recipient ("BRCV") is in the "disabled" state ("EN_R = 0"), then
the "BSEND" block receives a negative acknowledgment in the user
program (ERROR = 1; STATUS = 6 (decimal)). The send job is thus
completed.
There is no system-side strategy for repeating the "BSEND" job,
this is the responsibility of the user. This means that the send
job has to be repeated in the user program until the "BRCV" block
is ready to receive the data sent - "EN_R = 1" on the "BRCV"
block.
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