Siemens SIMATIC S7-1500 Function Manual page 354

Point-to-point connection
Bidirectional data exchange via communications modules with a serial interface between two
communications partners (and two only).
Port
Physical connector to connect devices to PROFINET. PROFINET interfaces have one or
more ports.
Primary CPU
If the R/H system is in RUN-Redundant system state, the primary CPU controls the process.
The backup CPU processes the user program synchronously and can take over process
control if the primary CPU fails.
Process image (I/O)
The CPU transfers the values from the input and output modules to this memory area. At the
start of the cyclic program, the CPU transfers the process image output as a signal state to
the output modules. The CPU then reads the signal states of the input modules into the
process image input. The CPU then executes the user program.
PROFIBUS
Process Field Bus - European Fieldbus standard.
PROFIBUS address
Unique identifier of a device connected to PROFIBUS. The PROFIBUS address is sent in
the frame to address a device.
PROFIBUS device
Device with at least one PROFIBUS interface either electrical (for example RS-485) or
optical (for example Polymer Optical Fiber).
PROFIBUS user organization
Technical committee dedicated to the definition and development of the PROFIBUS and
PROFINET standard.
PROFIBUS DP
A PROFIBUS with DP protocol that complies with EN 50170. DP stands for distributed I/O =
fast, real-time capable, cyclic data exchange. From the perspective of the user program, the
distributed I/O is addressed in exactly the same way as the centralized IO.
Communication
Function Manual, 11/2019, A5E03735815-AH
Glossary
353