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Communication Using Function Blocks
Data Consistency
Please note the following to ensure consistent data transmission:
Sender: Only access the send DB again once all the data has been transferred
(DONE = 1).
Receiver: Only access the receive DB again once all the data has been
received (NDR = 1). Then disable the receive DB (EN_R = 0) until you have
processed the data.
6.4.1
The S7 Transmits Data to a Communication Partner,
10 SEND_440 FB
The SEND_440 FB transfers a data field from a data block, specified by the
DB_NO, DBB_NO and LEN parameters, to the CP 440. The SEND_440 FB is
called cyclically for data transmission or, alternatively, statically (without conditions)
in a time-controlled program.
The data transmission is initiated by a positive edge at the REQ input. A data
transmission operation can run over several calls (program cycles), depending on
the amount of data involved.
The SEND_440 FB can be called cyclically with the signal state "1" at the
parameter input R. This terminates the transmission to the CP 440 and resets the
SEND_440 FB to its initial state. Data that has already been received by the
CP 440 is still sent to the communication partner. If the signal state "1" is at the R
input statically, this means that sending is deactivated.
The LADDR parameter specifies the address of the CP 440 to be addressed.
Error Display on the SEND_440 FB
The DONE output indicates that the job has been completed without errors.
ERROR indicates whether an error has occurred. If there was an error, the
corresponding event number is displayed for STATUS (see Section 8.3). If there is
no error, STATUS = 0. DONE and ERROR/STATUS are also output when
SEND_440 FB is RESET (see Figure 6-1). In the event of an error, the binary
result BR is reset. If the block is terminated without errors, the binary result has the
status "1".
Note
The SEND_440 function block does not have a parameter check. If there are
invalid parameters, the CPU branches to the STOP mode.
6-6
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
- Quick Links:
- Configuring and Parameterizing the Cp
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