Communications
configuring
System- and communication configuring D7-SYS - SIMADYN D
3-279
Edition 12.2003
From D7-SYS Version 6, communication links, for example PROFIBUS-
DP, SIMATIC-CPU
↔
FM 458-1 DP as well as for SIMATIC TDC or T400
and SIMADYN D can be alternatively configured using communication
blocks which have become recently available.
In this case, interface data is accessed from the CFC screen using new
blocks, which are inter-connected using a special pointer interface.
Both of these configuring methods (virtual interconnections and pointer-
based communications) can be used together on the same hardware
platform, in the same configuring (application software) and even for the
same interface.
3.24.4.1 Principle
mode of operation
Telegram blocks (CRV_T, CTV_P and S7RD_P, S7WR_P) allow access
to the receiving or to the sending data blocks (telegrams) by providing a
pointer to the particular data block.
This pointer is connected to read/write blocks (DRD…, DWR…).
Together with an offset, a write block can save the data at its input
connection at the required location in the buffer. A read block then
retrieves the appropriate data from the specified location of the receive
buffer and makes it available at its output.
This means that in principle, a virtual interconnection is replaced by a
(read/write) block and a "normal" CFC connection.
3.24.4.2 Applications
Pointer-based communications are especially advantageous where large
amounts of data are involved. For large amounts of data, it is simpler and
faster to configure and change and interconnections are more flexible.
Large data
quantities
