Addressing - Siemens SIMATIC S5 Manual

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

9.1 Addressing

In this Section
Configuration of
the DB 1
CPU 944 and
FB 250 and 251
!
9-2
Section 9.1 contains information on the following:
Section
9.1.1 Linear addressing
9.1.2 Page addressing
9.1.3 Addressing via the FB IM308C function block
9.1.4 Access commands for distributed I/O
The CPUs of the S5-135U and S5-155U series require you to generate a
DB 1 if you access consistent data areas in the P area. The rules governing
entries in the DB 1 are as follows:
CPU Entries under "Digital inputs /
CPU 922
CPU 928
CPU 946/947
CPU 948
The warning below applies to the use of the FB 250 and 251 function blocks
and the CPU 944 in conjunction with ET 200:
Warning
There is a possibility of outputs of the distributed I/O being inadvertently
reset.
The FB 250 and 251 function blocks with the CPU do not comply with the
specified sequence for accessing the distributed I/O. This can cause an inter-
ruption in data traffic on the SINEC L2 DP bus and a reset of the slave out-
puts. The IM 308-C may stop processing and the inputs/outputs are not up-
dated.
To avoid this difficulty, do not use the FB 250 and 251 function blocks with
the CPU 944 in the ET 200 distributed I/O system.
Topic
digital outputs"
decrementing
incrementing
decrementing
decrementing
ET 200 Distributed I/O System
EWA 4NEB 780 6000-02a
Page
9-5
9-7
9-10
9-11
Example
20, 19, 18, 5, 4
4, 5, 18, 19, 20
20, 19, 18, 5, 4
20, 19, 18, 5, 4