Parameters and properties
36
SIPROTEC PROFIBUS-DP - Communication profile
C53000-L1840-B001-03
Figure 2-1 Routing of the OLM status indications in DIGSI
External OLM If a SIPROTEC device with an electrical PROFIBUS module is connected to a redun-
dant optical ring topology using an external OLM (ref. to chap. 5.1) then a fibre-optical
line-break is signaled via a potential-free contact at the OLM device.
The output of this contact can be connected to an input of the SIPROTEC device and
used for evaluation of line-break indication.
SIPROTEC devices with surface-mounting case, two tier terminal top/bottom, are
delivered only with electrical PROFIBUS connection, in principle.
For the connection of these devices to an optical ring an external OLM device is
required.
Note:
• The OLM status indications are ON if a line-break is detected.
• A delay of max. 5 sec. between the line-break and the signalling of the interruption
can appear.
• The device recognizes the failure of a reception line.
A failure of the transmit line is signaled by the neighbor device.
• The “Byte offset” and “Bit mask” of the OLM status indications exist in DIGSI also
at SIPROTEC devices with electrical PROFIBUS module, then do not have any
meaning however.
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