PROFIBUS DP overview
PROFIBUS manual
Version FELD-V2002.02
Page 13
4.2 General
information
For PROFIBUS DP (cyclical data traffic), one must define at the
configuration stage how many bytes are transferred between master and slave
during each cyclical access. (GSD file)
The device is controlled using the data transferred from master to slave. This
data always consists of two bytes for the DIGIFORCE
®
type 9310 unit. The
function of these two bytes is explained on page <>.
The data transferred in the opposite direction from slave to master contains
the measurement results and status information. Since the DIGIFORCE
®
type
9310 is a highly complex piece of test equipment, there is an extremely large
amount of data could be transferred in this case. This is not always practical
however. For example, if one is only interested in the status information, it
makes little sense to transfer more than 90 bytes of measurement results per
access which the master makes no use of. On the other hand, there are
applications in which the measurement results from a specific window need
to be transferred; but this would not be possible if only the status information
per interface is available.
Hence in order to satisfy as many customer requirements as possible, nine
different combinations of different measurement results have been provided.
These different options specify what information is sent to the master. The
information content of the individual options (“modes”) ranges from a simple
short message (e.g. mode1 contains just PLC and status information; just 3
bytes are sent to the master in this case) to complex longer messages
containing a large amount of information (e.g. mode9 contains PLC and
status information, general curve data, entry and exit points, and minima and
maxima of windows 1-3; 99 bytes are sent to the master in this case). When
designing the system, the user can select the option that best meets his
requirements so that he receives precisely the data that he needs.
4.3 GSD
file
DIGIFORCE
®
equipment with the PROFIBUS option is supplied with a floppy
disk. This disk includes the device description file BUR_06E5.gsd (GSD file).
This GSD file describes the physical properties of the device (baud rate,
specific bit times, sent/received bytes per cycle etc.).
The structure, contents and encoding of this device description data is
standardized so that any DP slaves can be configured using configuration tools
from various manufacturers.
The GSD file does not specify what data is transferred or how this data should
be interpreted. The user must glean this information from the operating manual
and program his master accordingly.