VEGA VEGACOM 557 Profibus DP - Manual (Page 79)

VEGACOM 557 Profibus DP 79
Profibus DP multimaster system
DP Master (DPM2)
PLC
Profibus DP
Actor Sensor
decentralised inputs and outputs
DP Slaves
Several Masters can (reading) access to the data of the DP Slaves
CNC
DP Master (DPM1) DP Master (DPM1)
decentralised inputs and outputs
Data traffic between DPM1 and the DP
Slaves or planning instruments
The data traffic between the DPM1 and the
allocated DP Slaves is carried out automati-
cally by the DPM 1 in a predetermined, recur-
ring sequence. During the planning of the
bus system, the user determines the affilia-
tion of a DP Slave to the DPM1. Furthermore,
the user defines which DP Slaves will be
included in the cyclical useful data traffic and
which will be removed again.
Supplementary to the functions between DP
Master and DP Slaves, Master -Master com-
munication functions are available (see chart
1). They enable the planning of the system
by means of planning and diagnostic instru-
ments via the bus.
In addition to the upload and download func-
tions, the Master -Master functions of fer the
option of switching on/off the useful data
traffic between the DPM1 and the individual
DP Slaves dynamically , and of modifying the
operating condition of the DPM1.
Useful data transmission with Profibus DP
Profibus DP
Data-Exchange function
Final info
Output data
Head info
Head info Input data
Final info
Answering telegram
Enquiry telegram
DP Master DP Slave
direct answer
Supplement C