Siemens SIMATIC CP 440, Руководство пользователя

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Communication Using Function Blocks
6-10
Point-to-point connection CP 440 Installation and Parameter Assignment
A5E00057742-02
6.4.2 S7 Receives Data from a Communication Partner,
9 RECV_440 FB
The RECV_440 FB transmits data from the CP 440 to an S7 data area specified
by the DB_NO, DBB_NO and LEN parameters. The RECV_440 FB is called
cyclically for data transmission or, alternatively, statically in a time-controlled
program (without conditions).
With the (static) signal state “1” at the EN_R parameter, the check as to whether
data is to be read by the CP 440 is enabled. An active transmission can be aborted
with the signal state “0” at the EN_R parameter. The aborted receive job is
terminated with an error message (STATUS output). Receiving is deactivated as
long as the EN_R parameter has the signal state “0”. A data transmission can run
over several calls (program cycles), depending on the amount of data involved.
If the function block detects the signal state “1” at the R parameter, the current
send job is aborted and the RECV_440 FB is set to the initial state. Receiving is
deactivated as long as the R parameter has the signal state “1”.
The LADDR parameter defines the CP 440 to be addressed.
Error Display on the RECV_440 FB
The NDR output indicates that the job has been completed without errors (all data
read). ERROR indicates that 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. NDR and ERROR/STATUS are also output when
RECV_440 FB is RESET (LEN == 16#00 parameter) (see Figure 6-2). 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 RECV_440 function block does not have a parameter check. If there are
invalid parameters, the CPU branches to the STOP mode.