CPU ADAM 821x
Chapter 6 Deployment of the CPU 821xDP
ADAM 8000 Manual CPU 821x – Rev 1.1
6-21
Profibus employs a screened twisted two-core cable as communication
medium, which is based on the RS485 interface.
The RS485 interface employs differential voltages. For this reason it is less
sensitive to electrical interference than a voltage or a current based
interface. You may configure networks with linear as well as with tree
geometry.
Your ADAM CPU 821xDP carries a 9pin socket. You connect the Profibus
coupler directly to your Profibus network as a slave by means of this
connector.
Every segment supports a maximum of 32 stations. Different segments are
connected by means of repeaters. That maximum length of a segment
depends on the data communication rate.
The rate of data transfer of a Profibus-DP link is set to a value between
9.6kBaud and 12MBaud. Slaves are configured automatically. All the
stations on the network communicate at the same baudrate.
The structure of the bus is such that stations may be inserted or removed
without repercussions or to commission the system in different stages.
Extensions to the network do not influence those stations that have already
been commissioned. New stations or stations that have failed are detected
automatically.
The picture shows a Profibus connection under RS485 with indicated
terminating resistors:
L2P
shield
Master interface
Slave interface
3
8
L2P
3
8
shield
L2N
L2N
Transfer medium
