Modicon Fiber Optic Repeaters User`s Guide

Modicon
Fiber Optic Repeaters
User’s Guide
GM–FIBR–OPT Rev. B
1
Contents
GM–FIBR–OPT
1.1
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
1.2
Electrical Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
1.3
Fiber Optic Cable Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3
1.4
Typical Cable System Layouts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.1
Point–to–Point Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.2
Bus Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.3
Optical Star Coupler Configuration . . . . . . . . . . . . . . . . . . . . . . . . .
1.4.4
Self–Healing Ring Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . .
4
4
5
6
7
1.5
Selecting Fiber Optic Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
1.6
Calculating the Optical Path . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6.1
The Optical Power Loss Budget . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.6.1.1
Point-to-Point Example . . . . . . . . . . . . . . . . . . . . . . .
1.6.1.2
Star Coupler Connection Example . . . . . . . . . . . . . .
1.6.1.3 Calculating the Minimum Cable Distance . . . . . . . . . . . . . . . . . . .
1.6.2
Calculating the Number of Chained Repeaters . . . . . . . . . . . . . .
9
9
9
9
10
10
1.7
Recommended Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7.1
Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7.2
Termination Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7.3
Passive Coupler . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7.4
Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.7.5
Fiber Optic Cables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
11
11
11
11
12
12
1.8
Mounting Shelf/Panel Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13
1.9
Mounting Rack–Mount Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
14
1.10 Connecting the Repeater . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.10.1 Observing Safety Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.10.2 Rear Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.10.3 Connecting Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.10.4 Connecting the Network Cable . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.10.5 Setting the Remote I/O Shield–to–Chassis Jumper . . . . . . . . . .
1.10.6 Applying Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
15
15
16
17
17
18
18
1.11
Reading the Network Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
19
1.12 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.12.1 Troubleshooting Fiber Repeaters for Modbus Plus . . . . . . . . . . .
1.12.2 Testing Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1.12.3 Troubleshooting Fiber Repeaters for Remote I/O . . . . . . . . . . . .
1.12.4 Broken Cable Detection and Remedies . . . . . . . . . . . . . . . . . . . . .
1.12.4.1
Remote I/O Systems . . . . . . . . . . . . . . . . . . . . . . . . .
1.12.4.2
Modbus Plus Networks . . . . . . . . . . . . . . . . . . . . . . .
20
20
22
24
25
25
28
1.13
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
30
1.14
Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
32
Contents
iii
Figures
Figure 1
Figure 2
Figure 3
Figure 4
Figure 5
Figure 6
Figure 7
Figure 8
Figure 9
iv
Contents
Simplified Internal Schematic of Fiber Optic Repeaters . . . . . .
Example of Point–to–Point Connection . . . . . . . . . . . . . . . . . . . .
Example of Repeaters in a Bus Configuration . . . . . . . . . . . . . .
Example of Optical Star Configuration . . . . . . . . . . . . . . . . . . . . .
Example of Self–Healing Ring Configuration . . . . . . . . . . . . . . .
Mounting Dimensions: Shelf/Panel Models . . . . . . . . . . . . . . . .
Mounting Dimensions: Rack Mount Models . . . . . . . . . . . . . . . .
Rear Panel Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Indicators Layout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2
4
5
6
7
13
14
16
19
GM–FIBR–OPT
Fiber Optic Repeaters
User’s Guide
Introduction
Electrical Cable Connections
Fiber Optic Cable Connections
Selecting Fiber Optic Cable
Calculating the Optical Path
Recommended Materials
Mounting Methods
Installing the Repeater
Reading the Network Indicators
Troubleshooting
Specifications
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
1
1.1 Introduction
This manual describes how to install and operate Modicon Fiber Optic Repeaters (Part
Numbers 490NRP253, 490NRP254, 490NRP954, NWFR85D200, and NWFR89D200).
The repeaters have the following characteristics:
Model 490NRP253 provides a Fiber Optic Point-to-Point link between two Modbus
Plus connections. The Repeater contains one Fiber Optic Transceiver and one
electrical interface for Modbus Plus.
Models 490NRP254 and NWFR85D200 provide Fiber Optic Bus and electrical
Line-Drop links between Modbus Plus nodes or network segments. Each Repeater
contains two Fiber Optic Transceivers and one electrical Modbus Plus interface.
Models 490NRP954 and NWFR89D200 provide Fiber Optic Bus and electrical
Line-Drop links between Remote I/O nodes or network segments. Each Repeater
contains two Fiber Optic Transceivers and one electrical Remote I/O interface.
Part Number
Network
Application
Mounting Method
Power (Nominal)
490NRP253
Modbus Plus
Point-to-Point
Panel or Shelf
115/230 Vac, 24 Vdc
490NRP254
Modbus Plus
Bus and Line Drop
Panel or Shelf
115/230 Vac, 24 Vdc
NWFR85D200
Modbus Plus
Bus and Line Drop
19 in Rack
125/24 Vdc
490NRP954
Remote I/O
Bus and Line Drop
Panel or Shelf
115/230 Vac, 24 Vdc
NWFR89D200
Remote I/O
Bus and Line Drop
19 in Rack
125/24 Vdc
Except for their operating power and mounting methods, Modbus Plus repeater models
490NRP254 and NWFR85D200 are identical, and Remote I/O models 490NRP954 and
NWFR89D200 are identical.
POWER OK
POWER
SUPPLY
ELECTRICAL RX
ELECTRICAL TX
COMMUNICATION
CONTROLLER
MBUS+/RIO
ELECTRICAL
INTERFACE
EXTERNAL
CONNECTIONS
ELECTRICAL PORT
FIBER CH1 RX
FIBER CH1 TX
FIBER OPTIC
CHANNEL 1
INTERFACE
RX
TX
FIBER CH1
FIBER CH2 RX
FIBER CH2 TX
FIBER OPTIC
CHANNEL 2
INTERFACE
RX
TX
FIBER CH2
Figure 1 Simplified Internal Schematic of Fiber Optic Repeaters
2
Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.2 Electrical Cable Connections
Electrical connection to the Modbus Plus network is through the standard Modbus Plus
9–pin “D” connector. Connection to the Remote I/O network is through an “F”–style
connector and external Modicon Remote I/O 14 db tap. The electrical port of the
Repeater has the same network connections, specifications and restrictions as other
Modbus Plus or Remote I/O devices, and must be treated accordingly.
Refer to the Modbus Plus System Planning and Installation Guide (GM–MBPL–001), or
the 984 Remote I/O Planning Guide (GM–0984–RIO) for information regarding planning
your network configuration and the installation of the network electrical cable.
1.3 Fiber Optic Cable Connections
The fiber optic cable is connected to the fiber optic ports by a low–loss, industrial
ST–type connector. All of the repeaters are passive, meaning there is no regeneration
of the received signal in the repeater, and no additional delay to the signal produced by
the repeater.
Prior to installing the Fiber Optic Repeaters, fiber optic cable must be installed. Follow
the cable manufacturer’s recommendations for routing, installation, and testing of the
cable. Take care when terminating the ends of each fiber optic cable in order to
minimize loss of the optical signal. Follow the manufacturer’s guidelines for installing
optical connectors. Test the cable for proper attenuation prior to the connection of the
Fiber Optic Repeaters. The cable ends should be accessible at each installation site.
Allow sufficient cable length for a service loop and strain reliefs. Label each cable end
to facilitate future maintenance.
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
3
1.4 Typical Cable System Layouts
This section of your manual describes four typical configurations, and is illustrative of
the wide range of Fiber Optic Repeater applications.
1.4.1
Point–to–Point Configuration
Figure 2 shows a Point–to–Point connection for two segments of a Modbus Plus
network using Fiber Optic Repeaters.
The distance between the two Repeaters is limited by the maximum allowable power
loss from end to end. Power loss includes the fiber optic cable attenuation, connector
losses at the Fiber Optic Receiver and Transmitter ports, and the system margin of
3 dB. Methods of calculating the power loss are explained later in this guidebook.
BM85
BRIDGE
MULTIPLEXER
IBM PC/AT
490NRP253
FIBER OPTIC
REPEATER
490NRP253
FIBER OPTIC
REPEATER
COMPACT 984
(A984–145)
with MOTION
CONTROL
MODBUS
PLUS
TAPS
984–685E
PROGRAMMABLE
CONTROLLER
= COPPER CORE CABLE
= FIBER OPTIC CABLE
Figure 2 Example of Point–to–Point Connection
4
Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.4.2
Bus Configuration
Figure 3 shows the use of Fiber Optic Repeaters in a Bus configuration.
This type of configuration permits chaining multiple Repeaters to extend the fiber optic
link, thus increasing the distance between the nodes of the network. Such a
configuration permits connection of single nodes or clusters of nodes over the fiber
optic medium. The calculation of the number of chained Repeaters, and the total
distance of this type of fiber optic network, is explained later in this guidebook.
PANELMATE
PLUS 1000
COMPACT 984
(A984–145)
with MOTION
CONTROL
984–685E
PROGRAMMABLE
CONTROLLER
IBM PC/AT
984–785E
PROGRAMMABLE
CONTROLLER
MODBUS
PLUS
TAPS
490NRP253
FIBER OPTIC
REPEATER
490NRP254
FIBER OPTIC
REPEATER
490NRP254
FIBER OPTIC
REPEATER
490NRP253
FIBER OPTIC
REPEATER
= COPPER CORE CABLE
= FIBER OPTIC CABLE
Figure 3 Example of Repeaters in a Bus Configuration
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
5
1.4.3
Optical Star Coupler Configuration
The use of Optical Star Couplers (active or passive) can provide flexibility in the layout
of Modbus Plus and Remote I/O networks. Figure 4 shows one example of an Optical
Star Coupler configuration. Additional repeaters can be connected in order to extend
communication between electrical links.
If a passive Star Coupler is used, the use of 100/140 µm cable is recommended
because of its higher available optical power.
984–685E
CONTROLLER
490NRP253
FIBER OPTIC
REPEATER
#5
490NRP253
FIBER OPTIC
REPEATER
#6
OPTICAL
STAR
COUPLER
IBM PC/AT
490NRP254
FIBER OPTIC
REPEATER
#4
490NRP254
FIBER OPTIC
REPEATER
#1
490NRP253
FIBER OPTIC
REPEATER
#2
IBM PC/AT
IBM PC/AT
IBM PC/AT
490NRP253
FIBER OPTIC
REPEATER
#3
16–BUTTON
MMI
OPERATOR
PANEL
MODBUS
PLUS
TAPS
Compact–984
with MOT 201
Compact–984
with MOT 202
= COPPER CORE CABLE
= FIBER OPTIC CABLE
Figure 4 Example of Optical Star Configuration
6
Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.4.4
Self–Healing Ring Configuration
In some cases, because of the plant layout or network topology, it may be desirable to
connect the Modicon fiber optic repeaters in a “self–healing” ring configuration. To
support this configuration, the Repeaters have special features built into the signal
timing that allow them to be connected in a ring. The advantage of this approach is
that if there is a break in the ring, communications will continue on both “legs” of the
cable, thus adding a level of reliability to the system. However, it is important to note
that there is no sense bit, and detection of a fault is only accomplished through visual
inspection of the indicator lights on each Repeater, and by inspecting the physical
status of the cable. If fault tolerance with diagnostics is required from the network, the
recommended approach is to use dual cable Modbus Plus Communication Adapters
such as the AM–S985–800, which do have health and status bits associated with each
leg of the cable.
Figure 5 shows the “Self–Healing Ring” configuration of Modbus Plus or Remote I/O
links connected by Fiber Optic Repeaters over the optical medium. This configuration
can be achieved by connecting the second transceiver of the first and last Repeater, in
order to close the optical loop. This type of connection has all the advantages of the
previously described configurations, along with built–in redundancy. A broken
connection between any two Repeaters in the ring will automatically reconfigure the
network to continue the communication. The total length of the fiber optic cable in this
case can be up to 10 km (32,000 ft), and is essentially limited by the blanking built into
the Repeater to prevent the second pass of the data through the optical loop.
IBM PC/AT
984–685E
CONTROLLER
490NRP254
FIBER OPTIC
REPEATER
490NRP254
FIBER OPTIC
REPEATER
490NRP254
FIBER OPTIC
REPEATER
490NRP254
FIBER OPTIC
REPEATER
490NRP254
FIBER OPTIC
REPEATER
490NRP254
FIBER OPTIC
REPEATER
PANELMATE
PLUS 1000
IBM PC/AT
= COPPER CORE CABLE
984–785E
CONTROLLER
= FIBER OPTIC CABLE
Figure 5 Example of Self–Healing Ring Configuration
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
7
1.5 Selecting Fiber Optic Cable
When selecting which type of fiber optic cable to use, several factors must be
considered, among them the cable attenuation and the cable bandwidth. Cable
attenuation and bandwidth are parameters specified by the cable manufacturers, and
depend upon several factors:
the wavelength and the spectral width of the optical signal;
the cable index (use graded–index only) , and
the bandwidth (depends upon the size of the cable [50/125 µm, 62.5/125 µm, and
100/140 µm]).
The maximum attenuation for an 820nm optical signal is:
50/125 µm cable
3.5 dB/km
62.5/125 µm cable
3.5 dB/km
100/140 µm cable
5.0 dB/km
The bandwidth is the parameter limited by the dispersion of the optical signal along the
length of the cable. Two types of dispersion exist: modal dispersion and material
dispersion. The modal dispersion widely depends on the fiber core size, numerical
aperture (NA), and the difference in the refraction coefficient between core and cladding
material of fiber optic cable. This difference in refraction is called the cable index, and
results in a pulse spreading because of the different traveling distances for different
rays of light entering the multimode fiber. For example, a difference of 1% in refraction
coefficient between core and cladding material for step–index fiber produces a pulse
spreading (or pulse width distortion) of 50 ns/km.
Modal dispersion (and the resultant pulse width distortion) can be reduced by using a
smaller core size cable; using a graded–index fiber; and using a fiber with a smaller
numerical aperture.
Material dispersion results in pulse spreading at the end of the fiber because of the
difference in velocities for different wavelengths of the light signal, and depends upon
the wavelength and the spectral width of the transmit optical signal.
Shown below is the total amount of pulse width distortion (or “jitter”), contributed by
fiber optic cable for different cable sizes for 820 nm with +50 nm of spectral width
optical signal:
50/125 µm
62.5/125 µm
100/140 µm
3ns/km
5ns/km
7.5ns/km
=X
where “X’ is the “jitter”
in nanoseconds
per kilometer
Note The value of “X” is used in the formulas on Page 18 when calculating the
maximum number of chained repeaters.
8
Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.6 Calculating the Optical Path
1.6.1
The Optical Power Loss Budget
The maximum length of any optical path between two fiber optic repeaters must be
calculated separately, and depends on the total loss in all components used in the
path, including fiber optic cable, optical connectors, star couplers, and splices. The
sum of the losses in all components used in the optical path must not exceed the
specified Power Loss Budget for the chosen cable type.
The specified Power Loss Budget includes the loss of the two ST–type connectors
which connect at the two repeaters, and also includes the system margin of 3 dB.
Thus only other components such as additional connectors, star couplers, and splices,
along with cable attenuation, should be taken into account in calculating the loss.
1.6.1.1
1.6.1.2
Point-to-Point Example
Point–to–Point connection of 3 km for two repeaters with one splice using 62.5/125 µm
optical cable with attenuation of 3.5 dB/km.
Power Loss Budget in 62.5/125 µm cable
=
11 dB
Distance between Repeaters
Cable attenuation
Splice Loss
=
=
=
3 km
3.5 dB/km
.25 dB
System loss = 3.5 dB/km x 3 km + .25 dB
=
10.75 dB
(less than the allowable
Loss Budget of 11 dB)
Star Coupler Connection Example
Total end-to-end connection of 1 km for two repeaters through one star coupler using
100/140 µm optical cable with attenuation of 5 dB/km.
Power Loss Budget in 100/140 µm cable
GM–FIBR–OPT
=
16.5 dB
Kaptron 502402–4, 4 x 4, 100/140 µm Star Coupler
2 ST type connectors
=
Distance between Repeaters
=
Cable attenuation
=
8dB loss
1 dB each
1 km
5 dB/km
System loss = 5 dB/km x 1 km + 2 x 1 dB + 8 dB =
15 dB
(less than the allowable
Loss Budget of 16.5 dB)
Fiber Optic Repeaters User’s Guide
9
1.6.2
Calculating the Minimum Cable Distance
Because the transmit optical power greatly depends of the fiber size, the calculation of
the minimum distance is important to avoid overdriving the Repeater’s optical receiver.
When 50/125 or 62.5/125 µm cable is used, there is no limit on the minimum distance
required. The minimum distance for other fiber sizes must be calculated.
Receiver Sensitivity
Repeater Dynamic Range
Minimum =
Distance
=
=
–30 dBm
20 dB, meaning the maximum received
Signal = –10dBm
Maximum Optical Power (dBm) – Maximum Received Signal (dBm)
Cable attenuation dB/km
For example, if 100/140 µm fiber is used, the maximum optical power is – 4 dBm:
– 4 dBm – (–10) dBm
5 dB/km
= 1.2 km
Conclusion: When higher Optical Power is required when using the Optical Couplers
or Splitters, then it is permissible to use the larger size fiber. For short distances and
minimum distortions, use of the 62.5/125 size fiber is a better solution.
1.6.3
Calculating the Number of Chained Repeaters
Because the Repeaters are passive and do not regenerate the received optical data,
the number of chained repeaters is limited by the system’s total pulse width (jitter)
distortions.
The total allowable pulse width and jitter distortion is limited to 20% of the bit period, or:
for Modbus Plus
for Remote I/O
200 nsec
130 nsec
The Jitter contributed by Modicon’s Fiber Optic Repeaters is 10 nsec per box.
The Jitter contributed by the Modbus Plus or Remote I/O electrical interface is 40 nsec
(receive – transmit).
The formula to determine the number (N) of chained Repeaters is:
For Modbus Plus
N=
200 nsec – X(L)nsec – 40 nsec
10 nsec
where “L” is the total cable length (km),
and “X” is the jitter in ns/km
(see Page 16)
For Remote I/O
N=
130 nsec – X(L)nsec – 40 nsec
10 nsec
where “L” is the total cable length (km),
and “X” is the jitter in ns/km
(see Page 16)
10 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.7 Recommended Materials
Modicon offers these guidelines for selecting optical materials.
1.7.1
Connectors
Table 1 Suggested Connectors
1.7.2
Connector Type
Part Number
Description
St Bayonet
St Bayonet
Push–Pull St
ST Bayonet
ST Cleave and Crimp
Mechanical Line Splice
3M 6105
3M 6100
3M 6102
AMP 501380 Series
AMP 504034 Series
3M 2529 Fiberlok II
Epoxy, –40 to + 80° C Operational temp
Hot Melt, –40 to + 60° C
Epoxy, –40 to + 80° C
Epoxy, –30 to + 70° C
Cleave and Crimp, –40 to + 65° C
One size fits all, –40 to + 80°
Termination Kits
Table 2 Suggested Termination Kits
1.7.3
Kit Type
Part Number
Description
Bayonet or Push–Pull ST
Bayonet or Push–Pull ST
Bayonet ST
Bayonet ST
Mechanical Line Splice
3M 8154
3M 6150
AMP 501258–7
AMP 501258–8
3M 2530
Epoxy, 110 or 220 VAC, only for 3M Connectors
Hot Melt, 110 or 220 VAC, only 3M
Epoxy, 110 VAC, only AMP Connectors
EPOXY, 220 VAC, only AMP
Fiber Splice Prep Kit, Complete with Cleaving Tool
Passive Coupler
The AMP Model 95010–4 is a “pig–tail” option, and must be used with an enclosure
(use AMP Model 502402–4, a 19” Rack–Mount Enclosure, 1.7 ” high)
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
11
1.7.4
Tools
Table 3 Tools
Product
Part Number
Description/Use
3M (Photodyne) Optical Source Driver
9XT
3M (Photodyne) Optical Light Source
1700–0850–T
3M (Photodyne) Power Meter
3M Optical Light Source, 660 nm, visible
17XTA–2041
7XE–0660–J
Hand–held optical source driver
(requires a light source)
850 nm Light Source, ST Connectors,
for 9XT
Hand–held Fiber Optic Power Meter
Use with 9XT to troubleshoot raw
fiber, requires FC/ST patch cord
Connects FC connector on 7XE to ST
Permits use of above source and
meter to test raw fiber (2 required)
3M FC/ST Patch Cord
BANAV–FS–0001
3M Bare Fiber Adapter, ST Compatible
8194
1.7.5
Fiber Optic Cables
Modicon recommends the use of 62.5/125 graded index, multimode glass fiber for all
applications, except where the use of a passive coupler requires use of 100/140 fiber
for sufficient launch power to get a satisfactory signal budget. Many cable vendors
offer multiple choices for a variety of code ratings.
From the variety of cables offered by AMP or Belden, select the one that meets the
demands of your application. Wherever possible, Modicon recommends that a
multiconductor cable be considered, since it is inexpensive; it provides a backup in
case a cable gets cut in the process of pulling it; and you will always find uses for
the extra path(s), be it for voice, video, other communications, and/or other control
applications.
Most 62.5/125 cables are rated at 3.5 dB loss per km. With a multiconductor cable,
all the pairs come with an attenuation specification “as measured”.
12 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.8 Mounting Shelf/Panel Models
Fiber Optic Repeater models are available for mounting on a horizontal shelf or vertical
panel. Your choice of mounting method should provide access to the Repeater for
observing its status indicators. You should also locate the unit for easy access to its
rear panel connectors, for ease of installation and future servicing.
The bottom surface of shelf/panel models is fitted with pads for placement on a
horizontal surface, such as a shelf or platform.
For vertical mounting, use the brackets supplied with the unit for bolting to a panel.
The brackets have tabs that insert into slots on the Repeater’s bottom panel. No
additional hardware is required for securing the brackets to the Repeater. You will have
to furnish hardware for bolting the Repeater brackets to your panel. Four bolts are
required. Typically, standard 1/4–20 (10mm) bolts will be satisfactory.
The mounting brackets supplied with the unit for vertical panel mounting can also be
used to secure the unit on a horizontal surface.
TOP VIEW
ALLOW 4.0 IN (100 MM) REAR CLEARANCE FOR
ACCESS TO SWITCHES, CABLES, AND FUSE
Fiber Optic Repeater
490NRP954
8.3 IN
(211 MM)
1.53 IN
(39
MM)
5.25 IN
(133 MM)
11.5 IN (292 MM)
12.83 IN (326 MM)
14.08 IN (358 MM)
REAR PANEL VIEW
2.59 IN
(66 MM)
Figure 6 Mounting Dimensions: Shelf/Panel Models
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
13
1.9 Mounting Rack–Mount Models
Fiber Optic Repeater models are available for installation into a standard 19-inch rack.
Your choice of mounting method should provide access to the Repeater for observing
its status indicators. You should also locate the unit for easy access to its rear panel
connectors, for ease of installation and future servicing.
You will have to furnish hardware for bolting the unit into your rack. Four bolts are
required. When mounted, the unit can support itself by its front mounting bolts. It is
light enough in weight that you do not have to provide rear support within the rack.
FRONT PANEL VIEW
3.0 in
(76 mm)
3.47 in
(88 mm)
18.25 in (464 mm)
19.0 in (483 mm)
TOP VIEW
ALLOW 4.0 IN (100 MM) REAR CLEARANCE FOR
ACCESS TO SWITCHES, CABLES, AND FUSE
17.25 in (438 mm)
9.15 in
(232 mm)
8.48 in
(215 mm)
10.59 in
(269 mm)
1.44 in
(37 mm)
Figure 7 Mounting Dimensions: Rack Mount Models
14 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.10 Connecting the Repeater
1.10.1
Observing Safety Precautions
Before installing the Repeater, read the warning and cautions below. Follow them at all
times during the installation of the Repeater.
Warning DO NOT view the ends of fiber optic cable under magnification while a
transmit signal is present on the cable – SEVERE EYE DAMAGE MAY RESULT.
Use white light ONLY!
Caution If you are replacing a Repeater on an active Modbus Plus network, the
communication between the two links of the network will be temporarily disabled
as you replace the unit. Always plan for an orderly shutdown of your control
process (if necessary) while you replace a Repeater on an active network.
Caution Fiber Optic Repeaters CANNOT be operated with both 115 VAC and 24
VDC power applied at the same time (i.e., as with UPS backup), or with both 125
VDC and 24 VDC applied at the same time.
Caution When DC power is used, the POWER switch on the unit is disabled.
Power is supplied to the unit when source power is activated. Under DC power,
the unit does not provide surge protection.
Caution Do not remove the fiber optic connector covers until the fiber cable is
about to be connected. Also, if any optical connector will remain unused, do not
remove the connector covers from the unused connector. After connecting the
fiber cable, retain the dust covers for future use.
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
15
1.10.2
Rear Panel Connectors
AC/DC MODELS
24 VDC
CONNECTOR
CHASSIS
GROUND
SCREW
JP1
FIBER PORT 1
Tx
Rx
FIBER PORT 2
Tx
Rx
1
2
+ –
POWER
SELECTOR
PLUG
AND FUSE
POWER
SWITCH
POWER
CABLE
CONNECTOR
REMOTE I/O
SHIELD–TO–CHASSIS
JUMPER
(RIO MODELS ONLY)
MODBUS PLUS
CABLE
CONNECTOR
REMOTE I/O
CABLE
CONNECTOR
(RIO MODELS ONLY)
(MODBUS PLUS MODELS ONLY)
DC/DC MODELS
GROUND
FIBER PORT 1
JP1
Tx
Rx
FIBER PORT 2
Tx
Rx
1
2
+ –
125 VDC
+ –
24 VDC
REMOTE I/O
SHIELD–TO–CHASSIS
JUMPER
(RIO MODELS ONLY)
REMOTE I/O
CABLE
CONNECTOR
(RIO MODELS ONLY)
MODBUS PLUS
CABLE
CONNECTOR
(MODBUS PLUS MODELS ONLY)
Figure 8 Rear Panel Connectors
16 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.10.3
Connecting Power
Grounding: The Repeater obtains its ground through the chassis ground screw or
DC ( – ) wire. Connect the Repeater to the site ground. After making and securing
this connection, use a continuity tester to verify the Repeater chassis is grounded to
the site ground.
Connecting AC Power: Before connecting power, remove the power at its source.
The AC power cable supplied with the Repeater is keyed for North American 110–120
VAC power outlets. If necessary, install a different plug on the cable for the power
source at your site.
Remove the AC power cable from the Repeater. Set the power selector plug to the
110–120 VAC or 220–240 VAC position for the power source at your site. To do this,
remove the power selector plug by prying under its tab using a small screwdriver. Set
the plug to the proper voltage position as shown on the plug body, then reinsert it.
Insert the power cable into the rear panel connector. Plug the cable into the AC power
source.
Connecting DC Power: Before connecting power, remove the power at its source.
Connect the source to the DC power terminals, observing the proper polarity.
1.10.4
Connecting the Network Cable
The electrical cable should already be run to the Repeater site, with a connector
installed. If the cable and connector are not in place, refer to the Modbus Plus System
Planning and Installation Guide (GM–MBPL–001), or the 984 Remote I/O Planning
Guide (GM–0984–RIO), for information regarding planning your network configuration
and the installation of the network electrical cable.
The fiber optic cables should already be run to the site, with connectors installed. If
they are not in place, install them using the guidelines given earlier in this guide. Each
cable should be labeled to identify the transmit/receive link to which it connects.
Refer to Figure 8. Connect the Modbus Plus or Remote I/O electrical cable and the
fiber optic cables to the Repeater’s rear panel connectors. Secure the electrical cable
connector by tightening its two screws.
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
17
1.10.5
Setting the Remote I/O Shield–to–Chassis Jumper
The RIO cable shield–to–chassis jumper (on the rear of the unit) is shipped in the
neutral position (midway between “1” and “2” pins.)
Set the jumper to the position that will be used in your application.
When the jumper is in the “2” position, the RIO cable shield is connected directly to
chassis ground.
When the jumper is in the “1” position, the RIO cable shield is isolated from chassis
ground by a capacitor.
1.10.6
Applying Power
Before applying power, verify that all power connections, electrical cable connections,
and fiber optic connections are correctly installed for your application.
Applying AC Power: If you are using AC line power, apply AC to the Repeater site.
The Repeater’s main power switch controls the power to the unit. Set the power switch
to the “1” position (ON). The unit’s POWER OK indicator will illuminate.
Applying DC Power: If you are using DC power, switch on your DC to the Repeater.
The unit’s POWER OK indicator will illuminate.
18 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.11 Reading the Network Indicators
The layout of the Repeater’s indicators is shown in Figure 9. Refer to the illustration
applicable to your unit.
490 NRP 253
power OK
fiber port
power OK
fiber port 1
modbus plus
490 NRP 254
fiber port 2
modbus plus
FR85D200
modbus plus
fiber port 2
fiber port 1
power OK
490 NRP 954
power OK
fiber port 1
fiber port 2
remote I/O
FR89D200
remote I/O
fiber port 2
fiber port 1
power OK
Figure 9 Indicators Layout
The POWER OK indicator illuminates steadily when the Repeater has normal power
from the AC line or DC source and its internal power supply is operating normally.
The MODBUS PLUS or REMOTE I/O port indicator lights when a signal is received at
the Repeater’s electrical port. Each FIBER port indicator lights when a signal is
received at the fiber RX port.
If a port indicator fails to illuminate, it can indicate a lack of transmitted signal at
another network node. Before replacing the Repeater, check the cable connections on
the rear panel for a possible incorrect or loose connection. Also check the indicators
on other devices on the signal path to see if the signal loss is external to the Repeater.
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
19
1.12 Troubleshooting
1.12.1
Troubleshooting Fiber Repeaters for Modbus Plus
The indicator lights on Modicon’s Modbus Plus Fiber Optic Repeaters can be used to
debug and troubleshoot an application. In fact, when the function of the indicators is
understood, an installer can usually successfully bring on line good equipment, and
isolate fault down to the replaceable element of a system having faulty components.
This requires only a knowledge of the indicators’ operation and the use of known good
components.
This section explains how the indicators work, and how such knowledge can be used
by an installer to bring up a system; or in case of fault, how to troubleshoot down to
the replaceable component.
An example of indicators on a Modbus Plus Repeater is shown below:
power OK
fiber port
modbus plus
Power
Fiber port 1
= ON, steady green, when power is applied.
= ON, steady amber, when the fiber receiver is receiving packets from
another fiber optic repeater.
Modbus Plus = ON, steady amber, when the repeater is receiving packets from
devices on the wireside Modbus Plus network.
The Modbus Plus indicator is also activated by receive signals, illustrated conceptually
as:
RX
Optical Signal
TX
Fiber
Port
MB+
Modbus
Plus
Packet
20 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
The following example makes use of this information in bringing up two point–to–point
fiber optic repeaters. Connect the repeaters as shown:
490NRP253 FIBER
OPTIC REPEATER FR1
TX
RX
RX
TX
490NRP253 FIBER
OPTIC REPEATER FR2
POWER
POWER
NOTE: Connect Transmitter to Receiver
and Receiver to Transmitter. Duplex
cables have markings on one of the two
jackets to aid in identification.
Apply power and observe:
490NRP253 FIBER
OPTIC REPEATER FR1
Pwr
FP
TX
RX
RX
TX
MB+
490NRP253 FIBER
OPTIC REPEATER FR2
Pwr
FP
MB+
Both power lights should illuminate; no other lights should come on. Now connect a
single Modbus Plus Node to one of the repeaters:
MODBUS PLUS
NODE #1
490NRP253 FIBER
OPTIC REPEATER FR1
TX
RX
Pwr
FP
MB+
RX
490NRP253 FIBER
OPTIC REPEATER FR2
TX
Pwr
FP
MB+
The Modbus Plus Node generates packets, regardless of whether an application is
present; therefore, the Modbus Plus receiver is getting data, and its indicator is
blinking. The transmitter of FR1 passes the packets to the receiver of FR2, and its
fiber port indicator will blink.
Note The Repeater’s blinking pattern does not follow the standard Modbus Plus
network indicator flashing pattern of other Modbus Plus devices.
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
21
To verify proper operation of the rest of the system, relocate Modbus Plus Node 1 so it
is attached to FR2, as shown below. If the system is configured correctly, the
indicators should illuminate as follows:
Repeater
FR1
FR2
490NRP253 FIBER
OPTIC REPEATER FR1
Pwr
FP
Indicator
Fiber Port
BLINKING
OFF
TX
RX
RX
TX
MB+
1.12.2
Modbus Plus
OFF
BLINKING
490NRP253 FIBER
OPTIC REPEATER FR2
Pwr
FP
MODBUS PLUS
NODE #1
MB+
Testing Connections
Most failures in any kind of network are in the “medium”; that is, the wire, the fiber, and
their connections. Therefore, if any of the above configurations fail to give the
expected state of the indicators, your first suspicion should be that the cable, fiber, or
their terminations are at fault.
Test #1 In the above example, with Node 1 alone attached to FR1, if the Modbus
Plus light on FR1 does not blink, check for continuity of the Modbus Plus
cable, pin–to–pin. If this is correct, try attaching Node 1 to FR2. If the
Modbus Plus indicator on FR2 begins to blink, then Node 1 must be
transmitting, FR2 is receiving, and FR1 has failed and needs replacement.
If Node 1 attached to FR2 fails to cause the Modbus Plus indicator to blink,
Node 1 must be presumed to have failed.
Test #2 Assuming Node 1 attached to FR1 succeeds in illuminating the Modbus Plus
indicator, the FP indicator of FR2 should blink. If it does not, reverse
the fiber connections at either one or another (but not both) of the fiber
repeaters. [The correct connection is Transmitter to Receiver, Receiver to
Transmitter.] If the fiber port indicator of FR2 still fails to blink, reattach
Node 1 to FR2.
Test #3 After Node 1 is reattached to FR2, the Modbus Plus indicator of FR2
and the FP indicator on FR1 should both be on. If this test succeeds, you
have probably isolated the failure to the optical fiber now connected to the
receiver of FR2, the transmitter of FR1. To confirm this suspicion, reverse
the fiber connections to both FRs. If, as suspected, one fiber repeater is
“bad”, Node 1 attached to FR2 will no longer communicate to FR1. If
Node 1 is reattached to FR1, then the signal will transmit to FR2. Having
isolated the fault to the fiber, you will have to use other tools, such as a light
source and power meter, to verify discontinuity, and then confirm continuity
after correction of the fault.
22 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
Using the tests just described, most of the time you will be able to find the fault/failure
in a “broken” system without use of elaborate test equipment. Necessary components
(pre–tested for reliability) for such troubleshooting are:
a Modbus Plus node (It can – but need not – be running an application. All it must
do is pass tokens to be usable.)
a length of Modbus Plus cable, properly terminated
Fiber Optic Repeater
a fiber “pigtail”
knowledge and implementation of the above procedures.
The previous descriptions use the 490 NRP 253 Repeater, which has a single fiber
port. You can use a two–port Repeater in the same place as a single–port unit, but the
reverse is not true. When a two–port unit is used as a point–to–point device, one fiber
port is simply not connected.
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
23
1.12.3
Troubleshooting Fiber Repeaters for Remote I/O
Examine this conceptual diagram of a typical Remote I/O Fiber Optic application:
MASTER NODE
PLC
S
9
0
8
14 dB Tap
To Other
Drops
or Repeaters
Coaxial Cable
Coax
May or
May Not be
Connected to
Other Drops
or Repeaters
TX
FP2
490 NRP 954
FR1
Fiber
FP1
RX
RX
FP1
Fiber
To Other
Drops
or Repeaters
490 NRP 954
FR2
TX
FP2
May or
May Not be
Connected to
Other Drops
or Repeaters
14 dB Tap
DROP
J
8
9
0
There are well documented procedures for analyzing the wireside characteristics of this
type application, and it is recommended they be used as a first line of attack and
afterward whenever trouble is suspected.
If the S908 is working properly, it should cause the Remote I/O indicator for FR1 to
blink. If that indicator blinks as expected, then the fiber port indicator (FP1) for FR2
should blink, and the other (FP2) should be OFF. If the FP1 indicator does not blink,
check for proper connection (Transmit to Receive, Receive to Transmit). If no results
are obtained, substitute a known good FR for the one at FR2 and proceed from the
beginning. If this fails, the fault has been isolated to faulty fiber, and fiber testing
procedures must be used.
24 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
1.12.4
Broken Cable Detection and Remedies
1.12.4.1
Remote I/O Systems
Unlike S908 coaxial cable, fiber optic cable contains physically separate transmit and
receive lines. It is possible to lose communications through the receive line while the
transmit line remains intact, as depicted here:
PLC
S908 RI/O COAXIAL
CABLE TO DROP 2
490 NRP 954
S908 BRIDGE
RX
TX
FIBER OPTIC CABLE
BROKEN OR DISCONNECTED RECEIVE LINE
RX
TX
490 NRP 954
S908 BRIDGE
S908 RI/O COAXIAL
CABLE TO DROP 2
S908
RI/O
HEAD
B805
16 IN
B804
16 OUT
A break in the receive line as shown above will deprive the PLC of input data. Under
ordinary circumstances, the PLC will continue to drive outputs via the intact transmit
line. This could lead to outputs turning ON or OFF due to invalid (INPUT STATE: 0)
input data.
A method to prevent this from happening is to use STAT and SENS function blocks in
the PLC’s ladder logic to detect the loss of input communication. This logic can inhibit
outputs from improper state changes. Here is an example:
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
25
Seg. 1 #1 / 1
40101
STAT
#0187
#0001
( )
40285
00097
SENS
#0001
( )
00097
00001
( )
00097
00002
The STAT and SENS blocks monitor the I/O status of Drop #2 and inhibit outputs
00001 and 00002 if communications are lost. The STAT block provides access to the
system’s status, including the status of S908 communications. The status information is
stored in a table which starts at 40101 and has a length of 187 words (as shown in the
top and bottom nodes of the STAT block).
The SENS block has been programmed to sense the first, or “Communications Health,”
bit (SENS top node value = 1) of the 185th word in the status table (SENS middle node
value = 40285). This bit is the communications health for Drop 2 of the S908.
Coils 00001 and 00002 in the example have been configured as outputs in the I/O
Map, as shown below.
26 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
Utility
DelDrop HoldTme ASCPort GetDrop
Quit
F1––––––F2––––––F3––––––F4–––––––F5––––––F6–––––––F7–Lev8–F8–OFF–––F9
I/O MAP
800 SERIES I/O
Drop
:
2 of 32
Rack
:
1
Drop Hold Up Time:
3 (x100ms) ASCII Port :
0
Number Inputs:
16
Number Outputs :
16
___________________________________________________________________________________
Slot
Module
Type
101
102
103
104
105
106
107
108
109
110
111
984
984
B805
B804
B8
B8
B8
B8
B8
B8
B8
Reference Numbers
Input
Output
10001 –10016
00001 –00016
Data
Type
Module
Description
PLC–685E
PLC–685E
16–IN
B805
16–OUT B804
When the PLC’s Rx line is broken as depicted, the SENS’ed bit becomes 0 (OFF). The
middle node output to coil 00097 is set to 0 (OFF). Coil 00097 controls normally open
relays which, when power is removed, opens the circuits to coil 00001 and coil 00002,
thus inhibiting these outputs.
As an alternative, the logic could control a SKP block to prevent execution of that
portion of the network which would ordinarily output data through coils 00001 and
00002.
Refer to the Modicon 984 Programmable Controller Systems Manual (GM–0984–SYS)
for further information about using STAT and SENS and SKP blocks for this application.
Be sure to test your logic for correct performance.
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
27
1.12.4.2
Modbus Plus Networks
Due to the nature of fiber optic cable, it is possible to break or disconnect the TX line
independent of the RX line. The effect of this on a Modbus Plus network is shown in
the following example:
PC 3
(Running
MBPSTAT)
SEE NETWORK STATUS
DISPLAY “A”
PLC 1
PLC 2
MODBUS PLUS CABLE
490 NRP 253
MODBUS PLUS
PT–to–PT
TX
RX
RX
TX
FIBER OPTIC CABLE WITH BROKEN OR
DISCONNECTED TRANSMIT LINE
490 NRP 253
MODBUS PLUS
PT–to–PT
MODBUS PLUS CABLE
PLC 4
PLC 5
PC 6
(Running
MBPSTAT)
SEE NETWORK STATUS
DISPLAY “B”
Note that the sample network consists of six nodes, three on either side of each Fiber
Optic Repeater.
A broken Tx line from the standpoint of nodes 1, 2, and 3 will cause the Modbus Plus
network indicator LED’s on every node to illuminate. This “disconnect code” consists of
2 flashes, followed by a 2–second pause. The two PLC’s and the PC will cease data
communications. The MBPSTAT program, running on the PC at node 3, displays all six
nodes of the network, but no communication activity.
28 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
MODBUS PLUS NETWORK STATUS version 2.30
Global Data Activity, strike any key to exit
01
02
03
04
05
Adapter: 0
Success: 0
Failure: 0
06
DISPLAY “A”
On the other side of the break, nodes 4, 5, and 6 “re–form” into a smaller Modbus Plus
network. The Modbus Plus status LED’s at each node blink rapidly, indicating normal
communication among these three nodes. Note that MBPSTAT, running on the PC at
Node 6, displays only the three nodes of the re–formed network.
MODBUS PLUS NETWORK STATUS version 2.30
Global Data Activity, strike any key to exit
Adapter: 0
Success: 103
Failure:
0
04
05
06
00
00
00
DISPLAY “B”
GM–FIBR–OPT
Fiber Optic Repeaters User’s Guide
29
1.13 Specifications
Product Identification
The following table summarizes Fiber Optic Repeater part numbers and applications:
Part Number
Network
Application
Mounting Method
Power (Nominal)
490NRP253
Modbus Plus
Point-to-Point
Panel or Shelf
115/230 Vac, 24 Vdc
490NRP254
Modbus Plus
Bus and Line Drop
Panel or Shelf
115/230 Vac, 24 Vdc
NWFR85D200
Modbus Plus
Bus and Line Drop
19 in Rack
125/24 Vdc
490NRP954
Remote I/O
Bus and Line Drop
Panel or Shelf
115/230 Vac, 24 Vdc
NWFR89D200
Remote I/O
Bus and Line Drop
19 in Rack
125/24 Vdc
Except for their operating power and mounting methods, Modbus Plus repeater models
490NRP254 and NWFR85D200 are identical, and Remote I/O models 490NRP954 and
NWFR89D200 are identical.
System Specifications
Data Rate, Modbus Plus
1 Mbit/sec for Modbus Plus with Bi–Phase S
encoded data
Data Rate, Remote I/O
1.544 Mbit/sec for Remote I/O with Manchester
encoded data
Electrical Interface
Modbus Plus connection via 9–pin “D” connector
Remote I/O via “F” Connector
Optical Interface
ST–type Connectors
Pulse Width Distortion/Jitter
< 10 nsec
Bit Error Rate
10–9 over specified Optical Receiver Dynamic Range
Wavelength
820 nm
Power Loss Budget
(includes 3dB of
system Margin)
50/125 µm fiber – 7.0 dB
62.5/125 µm fiber – 11 dB
100/140 µm fiber – 16.5 dB
Maximum Distance for
point–to–point connection
2km over 50 µm fiber @ 3.5 dB/km
3km over 62.5 µm fiber @ 3.5 dB/km
3km over 100 µm fiber @ 5 dB/km
Reliability
Service Life
5 years
MTBF
50,000 hours (minimum) @ 30° C,
assuming fixed ground and component
stress within maximum specifications
30 Fiber Optic Repeaters User’s Guide
GM–FIBR–OPT
Power Requirements (AC/DC Models)
AC Input
DC Input
90–130 VAC
180–264 VAC
19.2–30 VDC
AC Internal Fuse Rating
120 mA
60 mA
300 mA
1 A @ 110 V
.5 A @ 220 V
Power Requirements (DC/DC Models)
DC Input
105–140 VDC
19.2–30 VDC
41 mA @ 125 VDC
300 mA
Retention on Power Loss
Remains in regulation > 10 ms
after removal of power
Inrush Current
6 A typical @ 125 VDC
Ground Leakage
1 mA @ 140 VDC
Optical Transmitter Specification
Optical Power
– 13.0 – 20.0dBm average power
(Measured with 1m Test fiber)
in 50/125 µm Fiber cable
–10.0 – 16dBm average power
in 62.5/125 µm Fiber cable
– 4.0 – 10.5dBm average power
in 100/140 µm Fiber cable
Rise/Fall Time
Silence or “OFF Leakage”
20 nsec or better
– 43 dBm
Optical Receiver Specification
Receiver Sensitivity
Dynamic Range
Directed Silence
– 30dB/m average power
20 dB
– 36 dB
Environmental Specification
Operating Temperature
Storage Temperature
Humidity
0 to 60° C
– 40 to + 85° C
10% – 95% non–condensing
Radiated Susceptibility
27 ... 500 mHz, 10 V/m (IEC 801-3, level 3)
Surge Withstand, Fast Transient
2 kV, 1 kV on I/O (IEC 801-4, level 3)
Surge Withstand, Oscillatory Wave 2.5 kV (IEEE 472).
(Surge Withstand tests into 50 ohms using V-3300 Generator, corresponds to
levels twice as high into open circuit)
GM–FIBR–OPT
Surge Transients
2 kV (IEC 801-5, level 3)
Electrostatic Discharge
8 kV, ten discharges (IEC 801-2, level 3)
Fiber Optic Repeaters User’s Guide
31
1.14 Glossary
attenuation The decrease in magnitude of power of a signal in transmission between
points. A term used for expressing the total losses on an optical fiber consisting of the
ratio of light output to light input. Attenuation is usually measured in decibels per
kilometer (dB/km) at a specific wavelength. The lower the number, the better the fiber.
Typical multimode wavelengths are 850 and 1300 nanometers (nm); single mode, at
1300 and 1550 nm. NOTE: When specifying attenuation, it is important to note if it is
nominal or average, room temperature, value or maximum over operating range.
bandwidth A measure of the information–carrying capacity of an optical fiber,
normalized to a unit of mHz/km. Fiber bandwidth depends on the length of the fiber,
and is usually expressed in mHz/km, even though the length dependence is not linear
for multimode fibers.
bit period The time required to define a data bit at a particular bit rate. [For Modbus
Plus, 1 mBit results in 1/Bit Rate = 1/1 x 106 = 10–6 = 1 msec. For Remote I/O,
1/1.544 x 106 = .648 µsec = 648 nsec.]
cladding The material surrounding the core of an optical waveguide. The cladding
must have a lower index of refraction in order to steer the light in the core.
connector A mechanical device used to align and join two fibers together to provide a
means for attaching and decoupling it to a transmitter, receiver or another fiber.
Commonly used connectors include the FC, FCPC, Biconic, ST Connector–Compatible,
D4, SMA 905 or 906.
core The central region of an optical fiber through which light is transmitted.
decibel (abbr. dB) Unit for measuring the relative strength of a signal.
digital A data format that uses two physical levels to transmit information. A discrete
or discontinuous signal.
dispersion The cause of bandwidth limitations in a fiber. Dispersion causes a
broadening of input pulses along the length of the fiber. Three major types are: (a)
mode dispersion caused by differential optical path lengths in a multimode fiber; (b)
material dispersion caused by a differential delay of various wavelengths of lights in a
waveguide material; and (c) waveguide dispersion caused by light traveling in both the
core and cladding materials in single mode fibers.
fiber A thin filament of glass. An optical waveguide consisting of a core and a
cladding which is capable of carrying information in the form of light.
fiber optics Light transmission through optical fibers for communication or signalling.
graded–index Fiber design in which the refractive index of the core is lower toward
the outside of the fiber core and increases toward the center of the core; thus, it bends
the rays inward and allows them to travel faster in the lower index of refraction region.
This type of fiber provides high bandwidth capabilities.
link A fiber optic cable with connector attached to a transmitter (source) and receiver
(detector).
local area network (abbr. LAN) A geographically limited communications network
intended for the local transport of data, video and voice.
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mechanical splicing Joining two fibers together by mechanical means to enable a
continuous signal. Elastometric splicing is one example of mechanical splicing.
megahertz (abbr. MHz) A unit of frequency that is equal to one million hertz.
micron (abbr. µm) Another term for micrometer. One millionth of a meter.
10exp–9meter.
mode A term used to describe a light path through a fiber, as in multimode or single
mode.
modulation Coding of information onto the carrier frequency. This includes amplitude,
frequency, or phase modulation techniques.
multimode fiber An optical waveguide in which light travels in multiple modes.
Typical core/cladding sizes (measured in microns) are 50/125, 62.5/125, and 100/140.
nanometer (abbr. nm) A unit of measurement equal to one billionth of a meter.
10exp–9 meters.
numerical aperture The number that expresses the light gathering power of a fiber.
point–to–point A connection established between two specific locations, as between
two buildings.
repeater A device which consists of a transmitter and receiver or transceiver, used to
amplify a signal to increase the system length.
receiver An electronic package which converts optical signals to electrical signals.
scattering A property of glass which causes light to deflect from the fiber and
contributes to losses.
source The means used to convert an electrical information–carrying signal to a
corresponding optical signal for transmission by fiber. the source is usually a Light
Emitting Diode (LED) or Laser.
splicing The permanent joining of fiber ends to identical or similar fibers, without the
use of a connector. See also fusion splicing and mechanical splicing.
star coupler Optical component which allows emulation of a bus topology in fiber
optic systems.
step–index fiber Optical fiber which has an abrupt (“step”) change in its reflective
index, due to a core and cladding that have different indices or refraction. Typically
used for single mode.
transmitter An electronic package which converts an electrical signal to an optical
signal.
wavelength The distance between the same point on adjacent waves.
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