Siemens SIMATIC S7-300 Series Reference Manual page 175

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.
DP Master
A ³ master which behaves in accordance with EN 50170, Part 3 is known as a
DP master.
DP Slave
A ³ DP Slave is operated on a PROFIBUS bus system, using the
PROFIBUS-DP protocol and behaves in accordance with EN 50170, Part 3.
Equipotential bonding
Electrical connection (equipotential bonding conductor) which gives the bodies of
electrical equipment and external conducting bodies the same or approximately
the same potential, in order to prevent disturbing or dangerous voltages from
being generated between these bodies.
Error display
Error display is one of the possible responses of the operating system to ³
runtime error. Other possible reactions are: ³ Error response in the user
program, CPU STOP status.
Error handling via OB
If the operating system detects a specific error (e.g. an access error with STEP
7), it calls the organization block (error OB) which is provided for this event and
which specifies the subsequent behavior of the CPU.
Error response
Reaction to a ³ runtime error. The operating system can react as follows:
Switching the PLC to STOP, call of an OB in which the user can program a
specific reaction, or display of the error.
External power supply
Power supply for signal/function modules and the connected hardware I/O.
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01
Glossary
Glossary-5