Glossary
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MODBUS RTU | SPI 3 | Trebing & Himstedt
SPI 3 configuration. If a telegram is larger than the data
channel, it needs to be fragmented.
Data transfer rate
Measurement for the speed of data transfer, specified in bits
per second.
Data word
16 bit area of memory in a data block.
Diagnosis
Detection, localization, classification and display of errors,
faults and messages.
DP
→
PROFIBUS
DP address
ID number used to uniquely identify each bus device
(station) in PROFIBUS DP.
DP standard
Bus protocol for PROFIBUS DB which is standardized in
EN 50 170.
Floating
Indicates that a component or circuit is not electrically
connected to ground
FREEZE
Control command that a DP slave receives from the DP
master. It causes the slave to store (freeze) the current
states of its inputs and to transfer the frozen values cyclically
to the master. The slave only starts to transfer the cyclically
updated values to the master again after it receives the
UNFREEZE command.
Galvanically isolated
With galvanically isolated I/O devices, the reference
potentials of control circuits and power circuits are not
electrically interconnected.
Ground
Conductive material (e.g. ground wire) whose electrical
potential is considered to be zero; all interconnected
inactive components of a device which cannot assume
dangerous voltages even in case of faults.
GSD
Device Data Base file (DDB), i.e. electronic device data
sheet which describes the features of the PROFIBUS device
uniquely and completely in a clearly specified syntax. You
can download a GSD file for the SPI 3 from the internet
(www.t-h.de); it is required to set up the device.
Handshake
Method used to synchronize data exchange. For example,
data can only be exchanged between a master and slave
