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Glossary
Data block
Default value
Distributed I/O de-
vices
E
ET 200
H
Hardware interrupt
Hot restart
Glossary-2
Data blocks are data areas in the user program which contain the user data.
There are two kinds of data blocks - - global data blocks and instance data
blocks. Global data blocks can be accessed by all code blocks while instance
data blocks are assigned to a certain FB call.
The default value is a realistic basic setting which is always used when no
other value is entered.
Distributed I/O devices are input/output devices which are located decen-
trally at some distance from the CPU and are not installed in the central rack.
A few examples are listed below.
ET 200M, ET 200B, ET 200C, ET 200U
S
S5-95U with PROFIBUS-DP slave interface
S
PROFIBUS- - DP connects the distributed I/O devices with the DP master.
The ET 200 is based on the PROFIBUS standard, part 1 of DIN 19245, and
the draft of the PROFIBUS- - DP standard (part 3 of DIN 19245).
The ET 200 utilizes the master- - slave principle. For example, the master in-
terface IM 308- - C or the CPU 315- - 2 DP can be the DP master.
The distributed periphery ET 200B, ET 200C, ET 200M and ET 200U can be
DP slaves, for example.
The modules causing the interrupt trigger a hardware interrupt due to a cer-
tain event in the process. The hardware interrupt is reported to the CPU. The
related ! organization block is processed in the order of the particular inter-
rupt's priority.
When a CPU restarts (e.g., because you turned the operating mode switch
from STOP to RUN or you turned on the power), either organization block
OB 100 (warm restart) or organization block OB 101 (hot restart, only with
S7- - 400) is executed before cyclic program processing (OB 1) begins. During
a hot restart, the process image of the inputs is read and processing of the
STEP 7 user program is continued at the point at which it was last terminated
(after STOP or power off).
CM35 Counter Module
(4) J31069-D0416-U001-A5-7618
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