Lenze I/O system 1000 System Manual - Manual (Page 387)

PROFIBUS communication
System configuration
Types
9
l
387 EDSIO1000 EN 7.0
9.2 System configuration
9.2.1 Types
PROFIBUS differentiates between active nodes (master) and passive nodes (slave).
Class 1 master (DPM 1)
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 master (DPM 2)
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.
Slave
Slaves are peripherals (PROFIBUS bus couplers) making process information (input data
and output data) available. Slaves only respond to direct requests by the master.
9.2.2 Mono−master system
Master
(DPM 1)
Slave 1 Slave 2 Slave 3
epm−t227
Fig. 9−1 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.