Westermo ODW-610-F2 - Manual (Page 12)

12 6651-22611
Multidrop, one data exchange
• The data exchange between PROFIBUS DP master and slave via ODW-610-F2 fibre
optic link will run from the ODW-600 units connected to PROFIBUS DP master
to the slave and the same way back to the master. The system delay is calculated by
summing the following:
1. Fibre: The optical fibre length PROFIBUS DP master to addressed slave
delay x 2.
2. Optical repeaters: The optical repeater delay * Number of optical repeat-
ers (excluding the ODW-610-F2 units connected to PROFIBUS DP master and
addressed slave) x 2.
3. Converter electrical to fibre: Signal processing delay x 2
(ODW-610-F2 units connected to PROFIBUS DP master and addressed slave).
4. Converter fibre to electrical: Signal processing delay x 2
(ODW-610-F2 units connected to PROFIBUS DP master and addressed slave).
Example
• Redundant ring, one data exchange between master and one slave.
One PROFIBUS DP master and 11 slaves with data rate 1.5 Mbit/s. 12 ODW-610-F2
units with a total fibre length of 40 km. A data exchange between master and one
slave.
1. Fibre: The total optical fibre ring length delay.
40 x 5 µs = 200 µs
2. Optical repeaters: The optical repeater delay x Number of optical repeat-
ers (excluding the ODW-610-F2 units connected to PROFIBUS DP master and
addressed slave).
(12 – 2) x 1 µs = 10 µs
3. Converter electrical to fibre: Signal processing delay x 2
(ODW-610-F2 units connected to PROFIBUS DP master and addressed slave).
(1 tBit + 1.0 µs) x 2 = (0.7 µs + 1.0 µs) x 2 = 3.4 µs
4. Converter fibre to electrical: Signal processing delay x 2
(ODW-610-F2 units connected to PROFIBUS DP master and addressed slave).
0.3 µs x 2 = 0.6 µs
5. The system delay is calculated by summing the delays in item
1 to 4 above:
200 µs + 10 µs + 3.4 µs + 0.6 µs = 216 µs