6.1 Configuration of redundant optical rings
31
6 Configuration
Version 2.4 04/07
6 Configuration
During configuration, the PROFIBUS network parameter
"Slot time" must be adapted to the network coverage,
network topology and the data rate due to frame delays
caused by lines and network components, as well as by
monitoring mechanisms in the network components.
6.1 Configuration of redundant optical rings
The following configuration conditions must be fulfilled in
the redundant optical ring (for details see Chap. 3.3
”Redundant optical ring“, p.13):
䡲 (1) Configuration of a non-existent bus subscriber
䡲 (2) Increasing the retry value to at least 3
䡲 (3) Checking and adjusting the slot time
Use the user-specific profile of the configuration tool to
set the parameters under (2) and (3).
Calculate the slot time with the following equation:
Slot time = a + (b
.
Length
OF
) + (c
.
Number
OZD
)
䡲 ”Slot time“ is the monitoring period in bit times
䡲 ”Length
OF
“ is the sum of all the optical fiber
lines (segment lengths) in the net-
work.
The length must be given in km!
䡲 ”Number
OZD
“ is the number of OZD Profi 12M …
in the network.
The factors a, b and c are dependent on the transmission
rate and are listed in the tables below.
Data rate a b c
12 MBit/s
1)
1651 240 28
6 MBit/s
1)
951 120 24
3 MBit/s
1)
551 60 24
1.5 MBit/s 351 30 24
500 kBit/s 251 10 24
187.5 kBit/s 171 3.75 24
93.75 kBit/s 171 1.875 24
45.45 kBit/s 851 0.909 24
19.2 kBit/s 171 0.384 24
9.6 kBit/s 171 0.192 24
Table 3a: Constants for calculating the slot time at DP standard
(redundant optical ring)
Data rate a b c
12 MBit/s
1)
1651 240 28
6 MBit/s
1)
951 120 24
3 MBit/s
1)
551 60 24
1.5 MBit/s 2011 30 24
500 kBit/s 771 10 24
187.5 kBit/s 771 3.75 24
93.75 kBit/s 451 1.875 24
45.45 kBit/s 851 0.909 24
19.2 kBit/s 181 0.384 24
9.6 kBit/s 171 0.192 24
Table 3b: Constants for calculating the slot time at DP/FMS
(”universal“) and DP with S595U (redundant optical
ring)
1)
see p. 32
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