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S5-115U Manual
The SEND block must be called in the control program in "ALL" mode at least once per interface
when
•
the CP can request data from a PLC on its own initiative, e.g., the CP 525 for display output or
the CP 535 with the job mode "READ PASSIVE".
•
a CP job is initiated with SEND DIRECT, but the CP asks the PLC for the data for this job via
"background communications".
•
the amount of data to be transmitted to the CP with SEND DIRECT is greater than the speci-
fied 1 frame size.
Description of the SEND DIRECT Function
The SEND DIRECT function works with the following parameters:
•
SSNR -
interface number
•
A-NR
-
job number (assign " 0")
•
ANZW -
job status word
•
PAFE -
parameter assignment error byte
•
QTYP -
source type
•
DBNR -
data block number
•
QANF -
source start address
•
QLAE -
amount of source data
Normally, the SEND DIRECT function is called in the cyclic part of the control program. The block
can be invoked in an interrupt service routine, but the job status word would not be updated
cyclically in this case. This task must then be performed by the CONTROL block.
The following two conditions must be met to transfer data or to activate a SEND job:
•
RLO "1" was forwarded to the function block
•
The CP enabled the job. (The "SEND/FETCH in progress" bit of the condition code word is "0").
If RLO "0" is forwarded (empty run), only the job status word is updated.
If "NN" is entered in the QTYP parameter, the source parameters have to be stored in the CP. If
not, the job is aborted with error.
Data interchange can proceed as follows:
•
The requested data is transferred directly to the CP.
•
The CP asks only for the job parameters.
•
The amount of data to be transmitted is too large. The block transfers the parameters and the
first data block to the CP. Then the CP requests the remaining data or an additional data
frame from the PLC via the SEND ALL function.
For the block user, the operator interface is the same in all initiation words. However, in the last
two cases, the instant of data transfer is postponed by at least one program cycle.
Description of the WRITE Function
If "RW" is entered in the QTYP parameter, the block transfers the indirectly specified source and
destination parameters to the CP. Then the destination parameters are sent along with the useful
data (requested via the SEND ALL function) to the communications partner (WRITE function).
EWA 4NEB 811 6130-02b
Integral Blocks
11-21
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