Transferring Data Sets - Siemens SIMATIC FM 458-1 DP User Manual

Configuring

4.3.4 Transferring data sets

Application
Features,
limit values
SIMATIC S7
access with SFC
FM 458-1 DP with
"virtual
connections"
4-12
If extremely large quantities of data are to be transferred, e.g. for
visualization applications (WinCC), or if data have to be transferred
between SIMATIC and FM 458-1 DP for an extremely high number of
drives.
 Memory available on the P bus: 114688 bytes (0x1C000 hex), for
various "data sets" (or "telegrams").
 max. 125 read and 125 write data sets
 max. length per data set (telegram): 240 bytes
 max. data quantity which can be transferred:
For internal data management and buffer mechanisms, the following
are required
- for received data sets, 2x data set length
- for sent data sets 3x data set length
The sum of the required bytes for all of the write and read data sets
may not exceed the above mentioned memory size of 114688 bytes!
Example:
Max. number of write and read data sets, each 240 bytes:
114688 bytes / (5 * 240 bytes) = 95.5733
A maximum of 95 write- and 95 read data sets, each with 240 bytes can
be configured.
"System Function Calls" SFC are used in the SIMATIC-CPU for data set
transfer:
 write SFC 58 data set (to the FM 458-1 DP)
 read SFC 59 to the data set (from FM 458-1 DP)
Refer to Chapter 2.1.6 for possible return values of the SFCs when the
operating state changes.
This coupling type is configured on the FM 458-1 DP in 3 steps:
1. Establish the coupling:
Configure a central communications block @CPB (from the
"SpezKomm" block family) to initialize and monitor the data set
coupling.
2. Define the send and receive data sets:
A function block must be configured for each data set (telegram):
CRV to receive,
CTV to send
Data/entries at the CRV/CTV connections:
Application Module FM 458-1 DP - User Manual
A5E01078222-02 Edition 03.2009