Balluff BIS M-370-000-A02, Manual, Page: 128 / 198

PROFIBUS INTERFACE
121
9
9.3 DATA EXCHANGE
The Master Profibus is usually a PLC (Siemens S7 or others) but it could be a PC based
device as well. The Profibus Processor unit is always Slave in the Profibus network.
PLC
RFID
Controller
RFID
Controller
RFID
Controller
RFID
Controller
RFID
Controller
Profibus Network
Profibus Master
Profibus Slaves
Profibus Slaves
Figure 66 - Profibus-DP Network Diagram
Basically two shared memory areas (Exchange Areas) are used to exchange information
between the SLAVE and the MASTER, both devices provide information to each other.
INPUT
AREA
OUTPUT
AREA
PLC BIS M-622-070-A01
Write Read
Write Read
Exchange Areas
Master Slave
Figure 67 - Profibus Communication
– Data Exchange Areas Diagram
Input and Output areas always refer to the Master: this means that the Processor unit writes
to the Input buffer and the PLC writes to the Output buffer.
The dimension of the exchange areas can be set to different values by the PLC through the
GSD file: the Profibus Processor unit allows up to
152 bytes as a combined total of the
Input and Output Areas .
NOTE
For further information regarding Fieldbus interfacing including
downloadable support files, go to the HMS website at
http://www.anybus.com, choose the link to the support page, select the
Anybus-CompactCom product type and then your network type .