Lenze EPM−T9XX Modular system - Manual (Page 259)

System configuration
Types
10
Networking via PROFIBUS−DP
10.2
10.2.1
L
10.2−1 EDSPM−TXXX−9.0−11/2009
10.2 System configuration
10.2.1 Types
PROFIBUS differentiates between active nodes (master) and passive nodes
(slave).
A class 1 master (DPM 1) is a central control which exchanges data with the slaves
in a fixed cycle. Typical DPM 1 are, for example, PLC or PC. Via an active bus
access, measured data is read cyclically from the input modules of the slaves and
setpoints are written to the output modules of the slaves.
Class 2 masters (DPM 2) are used for engineering, configuration or operation.
During commissioning, maintenance and diagnostics, for example, DPM 2 can be
used to configure the connected slaves, evaluate measured values and
parameters and query the status of the slaves. The data is transmitted acyclically.
DPM 2 do not have to be permanently connected to the bus. DPM 2 are provided
with active bus access.
Slaves are peripherals (PROFIBUS Gateway, PROFIBUS GatewayECO) making
process information (input data and output data) available. Slaves only respond to
direct requests by the master.
10.2.2 Mono−master system
Master
(DPM 1)
Slave 1 Slave 2 Slave 3
epm−t227
Fig. 10.2−1 PROFIBUS−DP mono−master system
In the case of mono−master systems, only one master on the bus is active during
operation. The slaves are coupled to the master via the transmission medium in
a decentralised manner. This system configuration achieves the shortest bus cycle
time.
Class 1 master (DPM 1)
Class 2 master (DPM 2)
Slave