Westermo ODW-641 - Manual (Page 23)

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About the automatic data rate detection
ODW-641 automatically detects the data rate by monitoring incoming PROFIBUS data
frames on both the electrical and optical interfaces. When the data rate has been estab-
lished the BA LED will go active.
If no data frames are transmitted for a period of time the automatic data rate detection
will restart and the BA LED will go inactive.
The idle time before the automatic data rate detection re-starts is set using DIP-switches
S2:4 and S2:5. The factory default setting is 5 seconds.
The automatic data rate detection determines the actual data rate by listening for
PROFIBUS Start Delimiters (SD1 – SD4) at the beginning of each data frame. If one or
more Start Delimiters are lost the automatic data rate detection will re-start.
The number of lost Start Delimiters before the automatic data rate detection re-starts
is set using DIP-switches S1:2 and S2:6 – S2: 8. The factory default setting is 31 faulty
frames (31 lost Start Delimiters).
Note: Start Delimiters can be lost during an electrical or optical disturbance.
For example a PROFIBUS slave unit is connected/disconnected or an optical fibre is
disconnected. It is advisable to start of by using the factory default settings and only
manipulate them if a problem exists.