
Glossary
Glossary-3
ET 200S IM 151-7 CPU Interface Module
A5E00058783-04
Diagnostic buffer
The diagnostic buffer is a buffered memory area in the CPU in which diagnostic
events are stored in the order of their occurrence.
Diagnostic interrupt
Diagnostics-capable modules use diagnostic interrupts to report system errors
which they have detected to the central CPU.
In SIMATIC S7/M7: When an error is detected or disappears (e.g. wire break),
the ET 200S triggers a diagnostic interrupt, provided the interrupt is enabled. The
CPU of the DP master interrupts the execution of the user program or
lower-priority priority classes and processes the diagnostic interrupt block
(OB 82).
In SIMATIC S5: The diagnostic interrupt appears in the station diagnosis. Using
cyclical querying of the diagnostic bits in the station diagnosis you can detect
errors such as a wire break.
Direct Communication
Direct communication is a special communication relationship between
PROFIBUS-DP nodes. Direct communication is characterized by the fact that the
PROFIBUS-DP nodes ”listen in” to find out which data a DP slave is sending
back to its DP master.
Distributed I/O Systems
Distributed I/O devices are input/output devices that are not used in the central
unit but set up at distributed locations at large distances from the CPU, e.g.:
ET 200S, ET 200M, ET 200B, ET 200C, ET 200U, ET 200X, ET 200L
DP/AS-I Link
S5-95U with a PROFIBUS-DP slave interface
Other DP slaves from either Siemens or other vendors
The distributed I/O systems are connected to the DP master via PROFIBUS-DP.
DP Master
A master that behaves according to the IEC 61784-1:2002 Ed1 CP 3/1
standard is designated a DP master.
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