ABB AC 800M User Manual page 55

Section 2 Transmission Technology
Delay time of optical fiber lines
The delay time is approx. 5 µs for each km of line. Converted to bit periods this
gives:
For calculating the line delay time, the maximum line length in km is multiplied by
the delay time corresponding to the transmission rate (see table).
Delay time of Optical Link Modules
The processing time per module is 1.5 tbit. The overall processing delay results
from the number of modules passed between telegram transmitter and receiver
multiplied by 1.5 tbit.
Delay time of other active PROFIBUS network components
The delay time is to be taken from the respective product documentation.
Transmission delay time T
The overall delay time is the sum total of the values determined in
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•
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3BDS009029R5001 B
Table 7. Delay times of optical fibre lines
Transmission rate in kbit/s
93.75
187.5
500.0
1500.0
Delay time of optical fiber and RS 485 lines.
Delay time of Optical Link Modules.
Delay time of other active PROFIBUS network components.
Calculation of transmission delay time TTD
9.6
19.2
TD
Delay time in tbit per km
0.05
0.10
0.47
0.94
2.50
7.50
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