Typical Installation Configuration
8
Below is a University Campus setup that illustrates the basic configuration of a typical Fiber Optic Network. This
scenario uses a combination of B+B SmartWorx fiber devices, including: 3 x Model FOSTC serial/fiber converters, 2 x
Model FOSTDRP fiber repeaters, and 1 x Model FOSTCDR DIN-rail mount fiber converter. Each of the items requires
a power supply (not shown).
Note 1: For the total transmission time over long fibers, the time to transverse the
fiber must be considered if delay is an issue. Light takes about 8.05 microseconds
to travel over 1 mile of fiber.
Note 2: When operating in a ring configuration, each node in addition to the two
in the point-to-point specification adds an additional 100 to 200 nanoseconds of
delay.
Note 3: When operating in a ring configuration, each node in addition to the two in
the point-to-point specification adds an additional 50 to 70 nanoseconds of skew.
Note 4: When operating in a ring configuration, each serial device must wait at
least this minimum time between receiving data from the ring and transmitting
back on to it.
Table 4. Recommended Maximum FOSTC’s
In A Fiber Ring Topology
BAUD RATE
RS-232
OPERATION
RS-422/485
OPERATION
460.8 kbps
n/a
2
230.4 kbps
n/a
4
115.2 kbps
2
8
57.6 kbps
8
16
38.4 kbps
16
24
19.2 kbps and lower
32
32
Table 3. Transmission Paramters
PARAMETER
Min.
Typical
Max.
Conditions
Data Rates (RS-232 Operation)
0 bps
-
115.2 kbps
-
Data Rates (RS-422/485 Operation)
0 bps
-
500 kbps
-
Power Supply Voltage
10 VDC 12 VDC
14 VDC
-
Power Supply Current Draw
-
140 mA
Full RS-485
termination
Optic Wavelength
-
820 nm
-
-
Fiber TX Launch Power
-17 dBm -13 dBm -10 dBm
-
Minimum Required Fiber RX Power
-
-25.4 dBm -24 dBm
-
Maximum Receiver Power
-
-
-10 dBm
-
Coupled Power Budget
-
12.1 dBm
-
-
Fiber Range
-
2.5 mi.
-
-
End-to-End Delay
-
2000 ns
2650 ns
Point-to-point
RS-232 operation
(See Notes 1 & 2)
End-to-End Delay
-
550 ns
1000 ns
Point-to-point
RS-422/485 operation
(See Notes 1 & 2)
End-to-End Skew
-
900 ns
1100 ns
Point-to-point
RS-232 operation
(See Note 3)
End-to-End Skew
-
50 ns
120 ns
Point-to-point
RS-422/485 operation
(See Note 3)
Maximum Total Diber Ring Length
-
-
5 mi.
(See Note 1)
Delay betw. RX & TX on Fiber Ring
52 µs
-
-
(See Note 4)
