Siemens SIMATIC ET 200SP System Manual page 255

BaseUnit
BaseUnits realize the electrical and mechanical connection of the I/O modules with the
interface module and the server module.
The inserted I/O module determines the signals at the terminals of the BaseUnits.
Depending on the selected BaseUnit, only certain terminals are available.
BaseUnit, dark-colored
Conduction of the internal power and AUX buses from the left adjacent module to the
subsequent modules on the right.
BaseUnit, light-colored
Inserted as first BaseUnit and opens a new potential group with electrical isolation. The
power and AUX buses are separate from the adjacent module on the left. It feeds the supply
voltage.
Baud rate
Data transmission rate; indicates the number of bits transmitted per second (baud rate = bit
rate).
BU cover
Cover for unused slots on the BaseUnit or placeholder for planned I/O modules. For a future
expansion, the reference identification label of the planned I/O module can be kept here.
Bus
Joint transmission path to which all participants of a fieldbus system are connected; has two
defined ends.
BusAdapter
Enables free selection of the connection technology for the PROFINET fieldbus.
Channel fault
Channel-specific fault, such as a wire break or short circuit.
In channel-specific passivation, the affected channel is either automatically reintegrated or
the fail-safe module must be removed and reinserted after the fault has been eliminated.
Channel group
The channels of a module are grouped together in a channel group. Certain parameters in
STEP 7 can only be assigned to channel groups, rather than to individual channels.
Distributed I/O system
System Manual, 12/2015, A5E03576849-AF
Glossary
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