VEGA VEGASCAN 850 Profibus DP signal output - Manual (Page 24)

24 Profibus DP signal output VEGASCAN 850
Supplement
Each Profibus DP system consists of differ-
ent instrument types. Depending on their
individual tasks, the instruments can be clas-
sified into three types:
DP Master class 1 (DPM1)
This is a central control, exchanging in a
predetermined message cycle information
with the decentralised stations (DP Slaves).
Typical instruments are e.g. PLC, CNC or RC.
DP Master class 2 (DPM2)
Instruments of this type are programming,
planning or diagnostic instruments. They are
used for setup to create the configuration of
the DP system.
DP Slaves
A DP Slave is a peripheral instrument (sen-
sor/actuator), reading in input information and
outputting output information to the peripher-
als. Instruments that only produce input or
output information are also possible. Typical
DP Slaves are instruments with binary inputs/
outputs for 24 V or 230 V, analogue inputs,
analogue outputs, counters etc.
System reaction
The system reaction of Profibus DP has been
standardised to ensure a large degree of
instrument exchangeability. In general, this is
determined by the operating condition of the
DPM1. The DPM1 can be controlled by the
planning instrument either locally or via the
bus. There are three different (main) system
conditions, as the following explains:
Stop
There is no data traffic between the DPM1
and the DP Slaves.
Clear
DPM1 reads the input information of the DP
Slaves and keeps the outputs of the DP
Slaves in safe condition.
Operate
DPM1 is in the data transfer phase. The in-
puts of the DP Slaves are read in a cyclical
data traffic and the output information is
transferred to the DP Slaves.
M
Profibus DP mono-master system
DP Master (DPM1)
PLC
Profibus DP
Actor Sensor Drive
decentralised inputs and outputs
DP Slaves