Glossary
32
Function code
Used to uniquely specify a function that can be executed in the
controller.
Galvanically isolated
With galvanically isolated I/O devices, the reference potentials
of control circuits and power circuits are not electrically intercon-
nected.
Ground
Conductive material (e.g. ground wire) whose electrical poten-
tial is considered to be zero; all interconnected inactive compo-
nents 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. A GSD file for the
SPI 3 you can download from the internet and 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 after the
master and the slave have “agreed” that the exchange should
take place.
ID byte
Configures the number and size of the bytes to be transferred
in a module.
Input byte
PLC address area which contains the data that the DP slave
sends to the DP master.
IP 20
Protection class specification to DIN 40 050. Components of the
device which carry voltages are protected against touching with
the fingers and against the penetration of solid objects with a di-
ameter of more than 12 mm.
Master
Active bus station that can send data to other bus stations and
request data from other bus stations.
Mirror
The input byte 0 of a data channel is called the mirror. The SPI 3
mirrors (returns a copy of) the stamp (q.v.) to confirm the oper-
ation or when user data is being processed. Mirror = 0 indicates
that the DP slave is ready for data exchange. If mirror = 0, input
byte 2 contains information on the length of the following user
data. Mirror
≠
0 indicates that user data will now follow or that
the operation is completed.
