Siemens SIMATIC RS 485 Manual page 42

Glossary
DP master
In the DP system, the DP master conducts the communication with the DP slaves according
to a defined algorithm. To do this, the DP master uses the functions for communication with
the DP slaves which are defined by PROFIBUS DP.
DP slave
The DP slave can be addressed by DP masters. The DP slave provides specified functions
(I/O data, diagnostics etc.) to the DP masters.
Master
A master station that is in possession of the token can send data to other nodes and request
data from these (= active node.)
Master-slave process
Bus access method where only one node is → master, and all other nodes are → slaves.
Nodes
Device whose data can be sent and/or received via the bus, for example a
DP master or a DP slave. This device requires a unique PROFIBUS address for this.
PROFIBUS
PROcess FIeld BUS, bit-serial fieldbus system standardized in IEC 61158-2 as "Type 3".
The standard specifies functional, electrical and mechanical properties.
PROFIBUS is a bus system that connects PROFIBUS compatible automation systems and
field devices on a cell and field level. PROFIBUS exists with the DP protocol (= Distributed
Peripheral I/Os), FMS protocol (= Fieldbus Message Specification) or PA protocol (= Process
Automation).
PROFIBUS address
To identify it uniquely, every bus node must be assigned a PROFIBUS address.
PCs/PGs are assigned PROFIBUS address "0".
DP master and slaves use a PROFIBUS address between 1 and 125.
PROFIBUS DP
PROFIBUS bus system with the DP protocol. DP stands for the German equivalent of
distributed I/O. The main task of PROFIBUSDP is the fast, cyclic data exchange between the
central DP master and the peripheral devices.
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RS 485 Repeater
Manual, 02/2011, A5E03382072-01