Communication blocks
Function Blocks - FM 458-1 DP
2-17
Edition 12.2004
The
computation time
essentially depends on the amount of data
transferred. A base computation time of approx. 10 µs as well as approx.
1 µs/byte can be assumed as nominal value.
The following blocks can be connected to this block (pointer input):
DRD, DRD_8, DRD_8D, DRD_8I, DRD_BY, DRD_D, DRD_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 bytes to be read
Number of bytes which are read by the SIMATIC-CPU via the P bus.
Max. number: 128 bytes
0
EN
Enable
For EN=1 at each call, the data sent from the SIMATIC-CPU (max. 128 bytes)
is read.
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
QF
Error status block
QF=1: There is an error; for details, refer to YF
0.0
YF
StatusInfo Block
§§ as for the DRD block!
16#0000
Computation time [µs]
FM 458-1 DP
10,0 + 1 for each byte
Can be inserted online
Yes
Can be configured in
Interrupt tasks
Cyclic tasks
Executed in
Initialization mode
Normal mode
Special features
The block must be configured in the
same
sampling time
as the blocks, connected via the pointer interface
(CFC connection via connections PTR). This can
only be used for the FM 458-1 DP!
Several S7RD_P blocks can be configured.
Although this is not a typical application, it can
make sense if, for example, the 128 byte area
should be read in several blocks or if data is
required in different sampling times.
Associated blocks
I/O
Configuring data
