Lenze 2130IB - Manual (Page 13)

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1.1.2. Explanations about PROFIBUS-FMS / mixed operation
PROFIBUS-FMS is the standard PROFIBUS according to part 1 and
part 2 of DIN19245. This operating mode supports the communication
on a bus with several masters (e.g. connected PLC systems) and with
a number of slaves (e.g. controllers). In addition, a mixed bus access
procedure is possible, where several PROFIBUS masters (e.g. PLC
systems) with the same priority can have access to PROFIBUS slaves
(e.g. controllers); see figure "extended structure".
Extended structure
DP, FMS or mixed operation
Slave Slave Slave
Master Master
PROFIBUS-FMS is based on the description of objects. Devices are
written in as virtual field devices (VFD = virtual field device); with one
device having several VFDs. Parameters or variants are displayed as
objects, which can be read out or written in using the services "Read"
or "Write", when an index (index + subindex) is specified. The FMS
device supplies an object description of every variable or data type
which contains the most important information about the
communication.
In a mixed PROFIBUS system, you can operate PROFIBUS-DP
devices and PROFIBUS-FMS devices on the same bus.
In a mixed system, however, only participants with the same
communication profile (FMS or DP) are able to communicate with
each other.
Lenze controllers have both communication profiles. In the operating
mode "mixed operation" PROFIBUS-FMS and PROFIBUS-DP are
active at the same time. This means that in a mixed system the Lenze
controller can be called up by PROFIBUS-FMS masters and
PROFIBUS-DP masters.
A disadvantage of the mixed operation compared with the pure
PROFIBUS-DP operation is the lower protocol efficiency. There are no
disadvantages compared with the pure PROFIBUS-FMS operation.
Therefore, a special operating mode for PROFIBUS-FMS for the
controller is not necessary.
The description of the PROFIBUS-FMS functions of the Lenze
controller can be obtained from the chapter "operating modeOperating
mode PROFIBUS mixed operation (FMS/DP)" (page 46).