Multimaster Mode - Siemens SIMATIC S5 Manual

IM 308-C – addressing, diagnostics and use of the FB IM308C
9.8.1

Multimaster mode

Definition
Tips for
multimaster mode
Rules
9-40
Multimaster mode means that there are at least two masters on the bus, for
example an IM 308-C and a CP 5431 or two IM 308-C master interfaces.
If there are two IM 308-C master interfaces on the bus, they may be in the
same host or in two different hosts.
Master system 1
Slave No. 9 Slave No. 10
Figure 9-5 Multimaster mode
A number of DP windows are reserved for addressing the FB IM308C. If, for
example, as shown in Fig. 9-5, you want to access two IM 308-C master
interfaces from one CPU, you can start the addresses of the first IM 308-C at
(F)F800 and those of the second IM 308-C at (F)FA00.
Bear in mind that you must select the appropriate DP window for
multiprocessor mode under the master parameters in COM ET 200 Windows.
COM ET 200 Windows supports the generation of multiple IM 308-C master
interfaces on one bus:
Enter the entire bus configuration before you start exporting the data to
memory card.
If you change the contents of one memory card, you must always
re-transfer all the data for each memory card.
So as not to sacrifice performance, assign the DP masters consecutive
station numbers that are as low as possible, e.g. 1, 2 and 3 for three DP
masters.
The highest station number (Highest Station Address, HSA) in the "Bus
parameters" dialog box should also be as low as possible.
Host system 1
IM 308-C No. 1 IM 308-C No. 2
Slave No. 11
Master system 2
Slave No. 12
ET 200 Distributed I/O System
EWA 4NEB 780 6000-02a