Glossary
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Trebing & Himstedt | SPI 3 | MODBUS RTU
Glossary
Address
→
Station address
Bit
Abbreviation for
bi
nary digi
t
, the smallest unit in the binary
system; it can have the value 0 or 1.
Bus
Cable with two defined ends which is used for exchanging
data between the connected bus stations.
Bus connector
Plug used to connect the bus stations to the bus cable.
Bus segment
→
Segment
Bus station
Device attached to the bus which can send data over the
bus (e.g. DP master), receive data over the bus (e.g. DP
slave), or amplify signals (e.g. repeater).
Byte
A byte consists of eight bits and is the smallest addressable
amount of memory.
Character timeout
Used to detect the end of a telegram in the case of an
unstructured flow of ASCII data. The telegram currently
being received is considered to be completed when the time
between two received characters is larger than the specified
character timeout.
Configuration
During configuration, the modules and the addresses of the
DP slave are assigned. The actual configuration describes
the modules which are actually present in the slave. the
required configuration describes the modules which should
be present in the slave. This approach allows an incorrect
configuration to be detected when the system is booted.
Configurator
Software for configuring PROFIBUS devices and for setting
parameters.
CPU
C
entral
P
rocessing
U
nit
Data block
Special memory area in a PLC which is optimized for storing
data; it consists of a specified number of words (or bytes) of
memory.
Data channel
A logical channel for exchanging data with the SPI 3. The
size of the data channel (i.e. I/O area) is dependent on the
