MPI bus addresses
Data transfer rate
does not start
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
On the SINUMERIK 840Di, nodes must not be plugged in or removed during
operation on the MPI bus.
Each node at the MPI bus must have a bus address in the range (0...31).
The data transfer rate at the MPI bus of the SINUMERIK 840Di must be set
to 1.5 Mbaud.
If no communication can be established as a whole or with individual nodes at
the MPI bus, check the following:
Is the data transfer rate of all nodes whose data transfer rate is set manually
(DIP switches) set to 1.5 Mbaud?
Are there any loosen cable connections?
Are all bus segments terminated correctly?
With the MPI bus operating at 1.5 Mbaud, bus segments not terminated cor-
rectly will certainly result in disturbances of communication.
In some components (e.g. HHU and HT 6), the terminating resistor is installed
Observe the following rules when installing an MPI network:
1. An MPI bus line must be terminated on both ends. To this aim, enable the
terminating resistor in the MPI connector of the first and last nodes and dis-
able the remaining terminating resistors.