3 Description of Functions and Measuring Principle User Manual PROFview XL
The master simulator can be operated at all baud rates and can determine all PROFIBUS stations of the
plant - and poll their ID numbers. These can be used to provide the assignment to the device master file
(DMF) of the manufacturer and to display the most important information. While the master simulator is run-
ning, the physical bus properties (quality level, disturbance-free voltage range and edge steepness) can be
measured and thus the signal quality of the entire PROFIBUS installation can be checked. Any stations which
are not functioning and any duplicated address assignments can thus also be located. The master simulator
continuously checks the whole possible address range (0 through 126) and will also find stations which are
only connected to the PROFIBUS later.
The master simulator must be operated exclusively on idle PROFIBUS plants, i.e. no other master station
must be operating. To disconnect the master station (if present and ready for operation) from the bus for use
of the PBT master simulator, the PBT accessories include a so-called bus disconnector. This is simply insert-
ed between the master station and its SUB-D 9 bus connector. When doing so, however, it should be ob-
served that the connector of the master station should not simply be removed; otherwise, a defect in the ca-
ble will result
4
and the terminator will not be powered at this point.
The frames of the PBT master simulator are not visible to the PBT. The address of the PBT changes dynami-
cally between the PROFIBUS addresses still free to ensure that the whole address range is available for the
stations during the start-up.
3.4.2 Station scan
This function automatically determines all stations connected to a PROFIBUS plant and ready for communi-
cation. This so-called live list will include all addresses of devices from which at least one valid frame has
been received. The completion of this measurement is the prerequisite both for measuring the physical bus
characteristics and for determining the topology. The station scan can be performed both on a running and
on an idle plant (in this case, with the PBT master simulator). When using the PBT master simulator, the ID
numbers (device codes) of the PROFIBUS stations are also determined, providing an assignment to the devi-
ce master files.
3.4.3 Detection of duplicated addressing
The PBT can detect PROFIBUS addresses assigned twice or more. This is done by detecting bus collisions.
This check for double addressing is performed during the station scan.
3.4.4 Topology scan
The topology scan function can determine the lengths of the lines between the individual PROFIBUS stations
and thus their topological order. This measurement must only be performed on an idle PROFIBUS plant, i.e.
without active master station (to this end, disconnect the master from the bus, as described in Section
3.4.1 "Master simulator") and with activated master simulator. The distance to the PROFIBUS master sta-
tions can therefore not be determined automatically.
4 In accordance with IEC 61158-2, each PROFIBUS connector should contain four inductivities in the signal lines A and B to com-
pensate the connection capacity of a PROFIBUS station. A PROFIBUS connector which is not connected will not have this capaci-
ty, and its inductivities will lead to undesired signal reflections.
10 PROFview XL
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