Communication blocks
2-18 Function Blocks - FM 458-1 DP
Edition 12.2004
2.3.3 S7WR_P Sending data to a SIMATIC-CPU (P Bus)
S7WR_P
Offs in 128By-PBus-Buffer
I OFF PTR DW
PtrBuffer Transmitdata
Number bytes to be write
I LEN QF BO
Error-Status Block
Number bytes to be write
BO EN YF W
StatusInfo Block
This block can only be used for the SIMATIC application module FM 458-
1 DP.
An FM 458-1 DP can send up to 128 bytes to the SIMATIC-CPU via the
P-Bus. The block S7WR_P sends data which were previously loaded
with write blocks via the pointer interface.
This block operates similar to the telegram block CTV_P. A maximum of
128 bytes can be transferred via this pointer interface and via the P bus
to the SIMATIC CPU. This data is previously loaded into the telegram
buffer using write blocks DWR… of the copy block CPY_Y.
This block only communicates with a SIMATIC-CPU. This means that the
required byte or word swap operations are automatically made
(depending on the data type of the connected read/write blocks). The
entry, which is normally required at the SW-connection of the read/write
block, is not evaluated and is therefore not required.
The computation time essentially depends on the amount of data
transferred. A base computation time of approx. 5 µs as well as approx.
0.7 µs/byte can be assumed as nominal value.
The following blocks can be connected to this block (pointer input):
DWR, DWR_8, DWR_8D, DWR_8I, DWD_BY, DWR_D, DWR_I, CPY_P
Default:
OFF Offs in 128By-PBus-Buffer
Offset of the value to be sent within the 128 byte memory relative
to the start of the buffer;
max. offset: Buffer length - length of the data type
0
LEN
Number of bytes to be written
Number of bytes which are to be sent to the SIMATIC CPU via the P bus.
Max. number: 128 bytes
0
EN Enable
For EN=1, at each call, the telegram buffer (max. 128 bytes) is sent to
the SIMATIC-CPU.
1
PTR PtrBuffer Transmitdata
Pointer to the telegram/data buffer; to connect with the same connection
type of other pointer-based communication blocks.
The CFC connection can be changed online.
The connection also includes monitoring information to ensure correct
configuring.
16#00000000
Symbol
Brief description
Mode of operation
Associated blocks
I/O
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