GarettCom 5843HRT User manual

3-44-0003-00 Printed in USA
Industrial Fiber Optic
Link/Repeaters \
\\
\
Models 5843HRT and 5844HRT
Models 5843SHRT and 5844SHRT
User Manual
UM5843
REV AD
Distributed by Solid Signal
www.solidsignal.com
877.312.4547

Warnings, Cautions, and Notes
Used in this Publication
WARNING
Warning notices are used in this publication to emphasize that hazardous voltages, currents, or other
conditions that could cause personal injury exist in this equipment or may be associated with its use.
In situations where inattention could cause either injury or damage to equipment, a Warning notice is
used.
CAUTION
Caution notices are used where equipment malfunction is possible if care is not taken.
NOTE
APPLICATION NOTE
Notes and Application Notes call attention to information that is especially significant to
understanding and operating the equipment.
This document is based on information available at the time of its publication. While efforts have been
made to be accurate, the information contained herein does not purport to cover all details or variations, or
to provide for every possible contingency in connection with installation, operation, or maintenance.
DYMEC assumes no obligation of notice to holders of this document with respect to changes
subsequently made.
DYMEC makes no representation or warranty, expressed, implied, or statutory with respect to, and
assumes no responsibility for the accuracy, completeness, sufficiency, or usefulness of the information
contained herein. No warranties of merchantability or fitness for purpose shall apply.
Permission is granted to make a reasonable number of copies of this document for the use within
the organization that has purchased the equipment.
\Link/Repeater is used exclusively to describe DYMEC's unique family of Fiber Optic Data Links.

Table of Contents
Page
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
1.2 Model 5843HRT and 5844HRT Link/Repeaters . . . . . . . . . . . . . . . 1-5
1.2.1 9 Pin Data Port D-Connector . . . . . . . . . . . . . . . . . . . . . 1-5
1.2.2 DTE/DCE Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
1.2.3 Repeat Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
1.2.4 Input Coupling Switch . . . . . . . . . . . . . . . . . . . . . . . . 1-6
1.2.5 Handshaking Switch . . . . . . . . . . . . . . . . . . . . . . . . . . 1-6
1.2.6 Drive Current Pin 8 Switch . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.2.7 Test Mode Switch . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.2.8 Optical Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-7
1.2.9 Diagnostic LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
1.2.10Power Connections . . . . . . . . . . . . . . . . . . . . . . . . . . 1-8
1.2.11Peripheral Equipment . . . . . . . . . . . . . . . . . . . . . . . . 1-9
2. Configurations, Operation, and Installation . . . . . . . . . . . . . . . . . . . 2-1
2.1 Point-to-Point Configuration . . . . . . . . . . . . . . . . . . . . . . . 2-1
2.2 Loop Operation - Master/Slave Configuration . . . . . . . . . . . . . . . . 2-5
2.3 Loop Operation - Peer-to-Peer Configuration . . . . . . . . . . . . . . . . 2-7
3. Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.1 Data Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.2 Optical Budget . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.2.1 Cable Attenuation Factors . . . . . . . . . . . . . . . . . . . . . . . 3-1
3.2.2 Extending the Distance . . . . . . . . . . . . . . . . . . . . . . . . . 3-2
3.3 Number of Repeats . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.3.1 Effects of Data Rate . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.3.2 Pulse Width Distortion . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
3.3.3 Temperature Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.4 Powering the Link/Repeater . . . . . . . . . . . . . . . . . . . . . . . . . 3-4
3.4.1 Model 5843HRT or 5843SHRT. . . . . . . . . . . . . . . . . . . . . 3-4
3.4.2 Model 5844HRT or 5844SHRT . . . . . . . . . . . . . . . . . . . . 3-4
3.5 Optional Station Power Voltages . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.6 Type of Communication . . . . . . . . . . . . . . . . . . . . . . . . . . 3-6
3.7 Selection of Fiber Optic Cable . . . . . . . . . . . . . . . . . . . . . . 3-6
4. Testing and Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.1 Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.2 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
5. Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1
5.1 Electrical and Optical Specifications . . . . . . . . . . . . . . . . . . . . 5-1
5.2 Mechanical Dimensions of the 5843HRT or 5843SHRT . . . . . . . . . . . 5-3
5.3 Mechanical Dimensions of the 5844HRT or 5844SHRT . . . . . . . . . . 5-4
6. Ordering Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-1

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-1
1. INTRODUCTION
DYMEC Models 5843HRT, 5843SHRT, 5844HRT and 5844SHRT are data communication Link/Repeaters which
allow the replacement of copper wire with fiber optic cable. Link/Repeaters simply convert electrical signals to light
for transmission, then, when received, convert the light signals to back electrical. This is done for RS-232 or TTL
formats.
Link/Repeaters are passive to software protocol. They are not addressable in communication protocols and do not
provide any control logic capability to support communication protocols. Link/Repeaters are designed with several
features that allow easy installation and flexibility in configuring for various communication systems.
Models 5843HRT and 5844HRT are similar except for the method in which they are powered.
Models 5843SHRT and 5844SHRT have the same features and functionality described for the Models 5843HRT
and 5844HRT respectively with the exception that they have single mode optics for use with single mode fiber cable.
NOTE
This manual makes reference to the Model 5843HRT and Model 5844HRT when describing features and
functionality of the Link/Repeaters. These descriptions generally apply to the Model 5843SHRT and Model
5844SHRT as well. When different, a specific reference is made identifying the particular model(s) and their
variation.
The User should read this manual to fully understand how to use the many features of the Link/Repeaters in an
effective communication system.
1.1 DEFINITIONS
The following terms are used in this manual:
IED:
An IED is any intelligent electrical device capable of RS-232 and/or TTL data communications, such as; a
computer, RTU, PLC, "smart" meter, relay, etc. The IED must have resident software or firmware that
manages the data communication logic, including protocol (formatting and timing), addressing capability (if
required), control logic software "handshaking", and scheduling.
Point-to-Point Configuration:
Two Link/Repeaters connected directly to each other.
Master/Slave Loop Configuration:
More than two Link/Repeaters connected together where the FOC connects the T optical port of one device
to the R optical port of the next unit in the loop. One IED is designated as the Master and controls all the
communication and the other IED’s act as Slaves and respond only when specifically polled by the Master.
Peer-to-Peer Loop Configuration:
More than two Link/Repeaters connected together where the FOC connects the T optical port of one device
to the R optical port of the next unit in the loop. Each IED has the capability of becoming loop Master as
allowed by the controlling software.
Echo:
The return of the Master's transmission back to the Master after traveling around the optical loop.
Optical Bus Configuration:
More than two Link/Repeaters connected together in a manner where the Master's transmission is heard by
all IED’s and there is no returning echo of this transmission.

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-2
Optical Star Configuration:
More than two Link/Repeaters connected together in a “hub and spoke” topology where the Master’s
transmission is heard by all IED’s and only the Master hears the polled Slave’s response and there is no
returning echo of the transmissions.
Master:
The Master is the IED that controls the loop in a Master/Slave loop. This IED is responsible for the control
of the loop, the polling of the Slaves for information, and the prevention of data collisions. All loop
communication is echoed back to and stops at the Master. The Master's Repeat Switch is always in the
"OFF" position.
Slave:
A Slave is an IED that is passive in a Master/Slave loop. A Slave's communication is under the control of
the Master, and should be controlled to prevent data collision in the loop. All communication generated by
the Master will be repeated through each Slave and back to the Master. A Slave's Repeat Switch is always
in the “ON” position.
Peer:
Peers are IED’s that have equal status and each may Master the loop when allowed by the software. A
Peer's Repeat Switch is always in the "OFF" position and a Peer IED controls pin 8 of its Link/Repeater in
order to obtain status as loop Master.
FOC:
Fiber Optic Cable.
Single-mode:
Single-mode fibers generally have diameters of 5µm to 13µm. Because of this small core, only one axial
path for light propagation is available through the fiber. The optics required to drive single-mode fiber have
to be highly focused so that minimum dispersion occurs. Though requiring more expensive optic emitters,
the benefit is that longer transmission distances (< 35 km) can be achieved.
Multi-mode:
Multi-mode fibers have core diameters of 50µm and larger. This larger core allows the light rays to be
propagated along several different paths down the fiber. The different paths include an axial component as
well as reflected components. Multi-mode units are economical and effective for transmission over
distances up to 6 km.
Repeat Switch:
The Repeat Switch enables (REP) or disables (OFF) the repeater function of the Link/Repeater.
DTE/DCE Switch:
Each Link/Repeater is provided with this switch (2 position) to easily adapt the device to either the DTE or
DCE configuration of the equipment which it connects.
Data Coupling Switch:
Each Link/Repeater is provided with this switch to easily adapt the device for either DC or AC electrical Input
data coupling. With AC data coupling the minimum input data rate is 1200 baud with DC data coupling there
is no minimum input data rate but a signal stuck on the input will lock up a loop, bussed or star network.

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-3
Pin 8 Output Option Switch: (Switch 5B)
Models 5843 and 5844 Links are provided with this switch to allow users who require more drive
current on the TTL output pin (pin 8) to accomplish this. Selections are High or Low. Consideration
should be given that the current value selected is appropriate for the input of the device being
connected to this data channel.
Test Mode Switch:
Models 5843 and 5844 are provided with this switch to allow users who wish to test the fiber
connections of the link with a built in diagnostic mode. This mode sends a 100Hz signal out the transmit
port as well as looping back the copper port (pins 2 and 3) for diagnostic purposes.
Handshaking Switch:
Each Link/Repeater is provided with this switch to easily adapt the device for use where the connected IED
needs to see active electrical levels on certain handshaking pins but does not require full handshaking
implementation.
Simplex Communication:
Transmit only or receive only communications.
Half Duplex Communication:
Sequential transmit and receive communications.
Full Duplex Communication:
Simultaneous transmit and receive communications.
T:
Transmit optical port.
TE:
Diagnostic LED that illuminates when the Link/Repeater is receiving an electrical transmit from its IED.
TO:
Diagnostic LED that illuminates when the Link/Repeater is transmitting a signal optically.
R:
Receive optical port.
RE:
Diagnostic LED that illuminates when the Link/Repeater is delivering a received optical signal electrically to
the IED.
RO:
Diagnostic LED that illuminates when the Link/Repeater is receiving a signal optically.
Optical Budget:
The optical budget is expressed in dB and is the amount of light loss tolerated for communication. The total
distance between two devices that a signal can be transmitted is determined by subtracting all the losses of
the circuit from the optical budget. Various factors in the optical circuit attenuate the light transmission and
must be accounted for to assure a reliable optical circuit. Key factors include cable attenuation (expressed
as dB per unit length), cable aging, and cable fittings (terminations, splitters, etc.).
Non Return to Zero (NRZ):
This type of encoding scheme does not require the voltage potential of each data bit to return to the zero
potential. No clock or timing recovery is provided with this type of communication except in the start and
stop bits usually found on each data word.
Return to Zero (RZ):
This type of encoding scheme requires the voltage potential of each data bit to return to the zero potential.
This allows timing recovery with each bit instead of just the start and stop bits of the data word.

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-4
Number of Repeats:
The Number of Repeats is the number of Link/Repeaters that may be connected in a loop configuration.
The sum of Slaves in a Master/Slave loop is the number of repeats for that type of loop. The number of
Peers minus one is the number of repeats in a Peer-to-Peer loop.
Asynchronous Communication:
This type of communication does not transmit a separate clock signal with the data signal. Link/Repeaters
support asynchronous communication. A communication scheme where the clock needs to be transmitted
(Synchronous Communication) is not supported unless the data and clock are transmitted together on the
same pin.

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-5
1.2 MODEL 5843HRT AND MODEL 5844HRT LINK/REPEATERS
NOTE
Link/Repeaters contain no serviceable parts. Opening the unit will void the warranty.
Each Link/Repeater consists of the following elements shown in Figure 1.
DYMEC MODEL 5943 LINK/REPEATER
RS-232
SWITCH ACCESS
MADE IN U.S.A.
PWR
ET
T
R
#6-32 Thread SST
Earth Ground
Diagnostic LED's
12 Vdc Power Input
Type "ST"
Fiber Connector
9 Pin D Sub
Connector
Removeable
Access Plate
OR
ER
OT
FIGURE 1. Elements of the Link/Repeater
1.2.1 9 Pin Data Port D-connector
The Link/Repeater connects directly to an IED's RS-232 or TTL communication port. The pin out
configuration of the Link/Repeater is shown in Figure 2. If the IED's port is not a 9 Pin D-connector or if
the IED's pin out configuration differs, an adapter is required.
•1 Chassis Ground •1 Chassis Ground
•2Transmitted Data (Link Input) •2Received Data (Link Output)
•3Received Data (Link Output) •3Transmitted Data (Link Input)
•4No Connection •4No Connection
•5 Signal
Common •5 Signal Common
•6(+5 Vdc Output) •6(+5 Vdc Output)
•7Repeat Enable / Disable •7Repeat Enable / Disable
•8 TTL Output •8 TTL Output
•99 to 15 Vdc Input •99 to 15 Vdc Input
Figure 2 Data Port Pin Assignments
DCE MODE DCE
DTE
DTE MODE DCE
DTE

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-6
1.2.2 DTE/DCE Switch (Two Position Switch)
The DTE/DCE Switch on the Link/Repeater switches the functions of pins 2 and 3 to accommodate the
IED configuration as DTE or DCE. This is a 2 position switch and both actuators must be set for the
Link/Repeater to work properly.
DTE: Data Terminal Equipment. By RS-232 standards, equipment designed as DTE transmits data
out of pin 2 on a 9 Pin D-connector and receives data on pin 3.
DCE: Data Communication Equipment. By RS-232 standards, equipment designed as DCE transmits
data out of pin 3 on a 9 Pin D-connector and receives data on pin 2.
1.2.3 Data Coupling Switch
The Data Coupling switch selects the electrical input conditioning, the AC position selects
capacitively coupled, the DC position is directly coupled.
AC: AC coupling has a minimum incoming data requirement of 1200 baud due to the capacitive
coupling. This option blocks DC electrical levels should the device connected fail and ‘stick
in a high level’. There is a 35 mS timeout for “stuck” output pins, after this time out the link
returns to LED off state.
DC: DC coupling allows DC logic levels to be transmitted over the fiber network, care must be
taken to guarantee that when any device stops transmitting packets that the input level
returns to a state that allows the T receptacle (emitter) to turn off. If it does not and the IED
is part of a loop, bussed or star network, the first device to transmit blocks all other devices
on the network from transmitting. *Single-Mode units cannot be DC coupled.
1.2.4 Repeat Switch
The Repeat Switch enables the repeater function in the “ON” position and disables it in the "OFF"
position.
ON: The repeater function available in the Link/Repeater is enabled. This function converts the
optical signal received on the R optical port to an electrical signal and delivers this signal to
the appropriate pin of the 9 Pin connector, as well as, re-transmits the signal optically out the
Link/Repeater's T optical port.
OFF: The repeater function available in the Link/Repeater is disabled. The Link/Repeater
converts the optical signal received on the R optical port to an electrical signal and delivers
this signal to the appropriate pin of the 9 Pin connector, and does not re-transmit the signal
optically out the Link/Repeater's T optical port.
1.2.5 Handshaking Switch 4B:
The Handshaking Switch outputs 5 Vdc on a standard handshaking pin in the “ON” position and
disconnects the pins it in the "OFF" position.
ON: Pin 6 (Data Set Ready) of the Link/Repeater output 5 Vdc. This signal is used by devices
requiring handshaking signals to indicate the readiness of the connected devices to receive
data.
OFF: Pin 6 of the Link/Repeater is not connected.

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-7
1.2.6 Pin 8 Current Output Option Switch 5B:
Models 5843 and 5844 Links are provided with this switch to allow users select one of 2 output source
drive current values for the TTL output pin (pin 8). Selections are 10ma (207 Ohm) or 20ma (67 Ohm).
Consideration should be given that the current value selected is appropriate for the input of the device
being connected to this data channel.
1.2.7 Test Mode Option Switch 3B:
Models 5843 and 5844 Links are provided with this switch to allow users who wish to test the fiber
connections of the link with a built in diagnostic mode. This mode sends a 100Hz signal out the
transmit port as well as looping back the copper port (pins 2 and 3) for diagnostic purposes.
DCE/DTE
2
1
Test Mode ON/OFF
Data Coupling DC/AC
Repeat M ode ON/OFF
High/Low
Hanshaking DSR/OFF
421 3 5
FIGURE 4. Switch Settings
1.2.8 Optical Ports
There are two optical ports, T and R. The T optical port transmits data signals optically to the next
Link/Repeater. The R port receives the optical data signal from another Link/Repeater's T optical
port. Each port is fitted with an "ST" type receptacle for attaching the FOC.
R
Fiber Connector
T
Fiber Connector
9 Pin D Sub
Connector
Pin 1
Figure 3 Optical Ports and Electrical Port

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-8
1.2.9 Diagnostic LEDs
Each Link/Repeater is equipped with four diagnostic LEDs. They represent the electrical transmit (TE),
optical transmit (TO), electrical delivery (RE), and optical receive (RO) paths. These LEDs, when
illuminated, show that the appropriate path is active. When the Link/Repeater is transmitting, both TE
and TO LEDs will illuminate to show the transmit path active. When the Link/Repeater is receiving light
signals, both RO and RE LEDs will illuminate. If the unit is in the repeat mode and receiving light, the
RO, RE and TO LEDs will illuminate because the signal is being re-transmitted out the optical port, as
well as, being delivered to the D-connector. LEDs only illuminate when the path is active; powering of
the unit does not illuminate the LEDs unless their path is active. When data is present on the paths, the
LEDs may "flicker"; this is normal. The diagnostic LEDs may be used for trouble shooting by observing
that the illumination of the LEDs corresponds with activity in the unit. See Figure 5 for LED patterns and
signal paths.
Normal Repeat
PWR
RO
RE
OT
ET
23
Normal Receive
PWR
RO
RE
OT
ET
23
Normal Transmission
23 PWR
RO
RE
OT
ET
FIGURE 5. Diagnostic LED patterns and signal paths
NOTE
The LEDs only illuminate when there is signal traffic and are not illuminated during signal "quiet" times.
The LEDs may "flicker". This is normal operation.
1.2.10 Power Connections
1.2.10.1 Powering Model 5843HRT
Model 5843HRT may be powered either through pin 9+ (and pin 5-) of the 9 Pin D-
connector or the external connector located on the back of the unit:
1) When powering the 5843HRT via pin 9 of its D-connector, the IED must supply at
least 250 mA (340mA for the 5843SHRT). The voltage should be regulated and within
a range of 9 to 15 Vdc.
2) When powering the 5843HRT via its external connector, DYMEC offers a 110 Vac to
12 Vdc adapter (Model 4310S) that is designed specifically to plug into this connector.
Model 4310S assures reliable power over the temperature range of 0°C to + 70°C.

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-9
CAUTION
Regardless of the power connection used, Model 5843HRT requires
250 mA (340 mA for the 5843SHRT) within a range of 9 to 15 VDC.
An inadequate power supply not capable of supplying 250 mA over
the entire operating temperature range may cause the Link/Repeater
to malfunction.
1.2.10.2 Powering the Model 5844HRT
Model 5844HRT may be powered either through pin 9+ (and pin 5-) of the 9 Pin D-
connector or the power connector located on the side of the unit:
1) When powering Model 5844HRT via pin 9 of its D-connector, the IED must supply
at least 250 mA (340 mA for the 5844SHRT). The voltage should be regulated and
within a range of 9 to 15 Vdc.
2) Model 5844HRT has an internal regulated power supply that may be connected
directly to ac or dc station power. The station power may be 90 to 250 Vac, 50/60
Hz or 90 to 250 Vdc. The station voltage may be unregulated, but the circuit must
be capable of providing a minimum of 35mA (50mA for the 5844SHRT)
continuously. Model 5844HRT has a ground stud (#6-32 bolt) and a power
connector on the side of the case. If Model 5844HRT is powered through the power
connector, then connect a suitable earth ground to the grounding stud on the side
of the Link/Repeater. Remove the power plug from the power connector of the
Link/Repeater. Connect the power lines to the power plug being careful not to
leave any wire strands exposed.
This power input to the Model 5844HRT is Surge Withstand Protected to IEC
61000-4-4, EN61000-4-5 Standard and ANSI/IEEE C37.90.1-1989.
NOTE
Model 5844HRT or Model 5844SHRT can be ordered to accommodate 24 Vdc - 48 Vdc power.
WARNING
When installing a Model 5844HRT or a 5844SHRT Link/Repeater, an
earth Ground must be attached to the Ground Stud on the side of the
case before connecting to power. Failure to follow this procedure
may result in electrical shock to personnel.
1.2.11 Peripheral Equipment
1.2.11.1 IED
An IED is any intelligent electrical device such as; a computer, RTU, PLC, "smart" meter,
relay, etc., that has the ability to communicate data via RS-232 or TTL format. The IED
should have a communication port for the connection of the Link/Repeater. If the IED's
communication port connector does not accept the Link/Repeater to be plugged in directly,
an adapter must be made to accommodate the connection. Care should be taken to assure

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
1-10
that the correct signals are connected to each other. See Figure 2 for the Link/Repeater's
pin signal assignments. Check your IED's equipment manual for its signal assignments.
The IED must also have intelligent software to execute the data communication. This
intelligence needs to logically manage the data and signal traffic, including any addressing,
token passing, "handshaking", data formatting and scheduling.
1.2.11.2 Fiber Optic Cable (FOC)
The selection of the fiber optic cable is important. High quality cable can assure the
maximum performance of your Link/Repeater. Important factors to consider are the
manufacturer's specification on attenuation per unit length, attenuation due to aging,
diameter, and tensile strength. Choosing the best quality FOC for your installation is
important.
NOTE
DYMEC can supply multi-mode glass FOC in either Simplex, Duplex, or Breakout construction, cut to length,
terminated, polished and tested. The specification for all DYMEC supplied cables are as follows:
Fiber Diameter: 62.5/125µm
Tensile Strength: 100 kpsi
L
oss: 3 dBperkilometer
Aging Loss: less than 3 dB
Model 5843HRT and Model 5844HRT Link/Repeater optical ports are designed for ST
type terminations and are compatible with multi-mode FOC ranging from 50 µm to 200
µm.
Model 5843SHRT and Model 5844SHRT Link/Repeater optical ports are designed for
ST type terminations and are compatible with single-mode FOC ranging from 5 µm to
13 µm.

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
2-1
2. CONFIGURATIONS, OPERATION, AND INSTALLATION
Model 5843HRT and Model 5844HRT Link/Repeaters can be connected in a Point-to-Point configuration, in a
Master/Slave Loop, in a Peer-to-Peer Loop or an optical bus depending on the needs of the overall
communication system.
These models are designed to accept electrical inputs per RS-232 and TTL standards.
RS-232 data communication signals are always on pins 2 or 3 (transmit or receive pin assignment is based
upon the setting of the DTE/DCE switch) of the Link/Repeater's 9 Pin D-connector.
For TTL data communication, the transmit (Link/Repeater receive) is on either pin 2 or 3 depending on the
setting of the DTE/DCE switch and the receive (Link/Repeater transmit) is on pin 8.
When the Link/Repeater has a high TTL potential (above 2.4 volts) on its transmit pin, it will transmit optically.
All signal voltage levels on the 9 Pin D-connector are referenced to pin 5 of the D-connector.
NOTE
Pin 8 always has the TTL data output signal present even during RS-232 communication. Be sure that the
presence of the TTL signal on pin 8 will not adversely affect the IED operation.
It is also possible to optically connect Link/Repeaters together which are connected to IED’s with different
electrical formats. It is possible to optically interconnect Models 5845HRT and 5846HRT (operating EIA
422/485) to DYMEC Models 5843HRT and 5844HRT which are connected to IED’s operating RS-232 or TTL
formats.
APPLICATION NOTE
DYMEC Models 5843HRT, 5844HRT, 5845HRT and 5846HRT can optically communicate to each other,
eliminating the need for format translation interfaces, provided all connected devices are operating at the
same data rate.
2.1 POINT-TO-POINT CONFIGURATION
For Point-to-Point operation, two Link/Repeaters are optically connected to each other.
This configuration permits full duplex communication (simultaneous transmitting and receiving), half duplex
communication (sequential transmitting and receiving), and simplex (transmitting or receiving only).

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
2-2
APPLICATION NOTE
In Point-to-Point operation, the communication logic (control software) of the IED’s must manage:
1) The transmission of data signals.
2) The receipt of data signals.
3) Any "handshaking" required must be accomplished through software.
235
Master
TR
COM
2
35
Slave
TR
COM
DTE
DCE
ON
OFF
DTE
DCE
ON
OFF
FIGURE 6. Point-to-Point Configuration
2.1.1 Installation
1. Set the DTE/DCE Switch to the appropriate position for each Link/Repeater and its respective IED.
2. Set the Repeat Switch on all of the units to the "OFF" position.
3. Connect the Link/Repeater to the IED's RS-232 or TTL communication port (including any adapter
that may be needed).
4. Connect the Fiber Optic Cables (T of one device to R of the second device).
5. Connect power to the Link/Repeater as follows:
A) If the unit is to be powered through the D-connector (9 to 15 VDC on pin 9 referenced to pin
5), then the unit is energized when it is connected to the D-connector (the power LED will
illuminate).
B) Connect power leads to the power connector and then energize the power source. The unit
is now powered (the power LED will illuminate).

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
2-3
WARNING
When installing a Model 5844HRT or 5844SHRT Link/Repeater, an
earth Ground must be attached to the Ground Stud on the side of
the case before connecting to power. Failure to follow this procedure
may result in electrical shock to personnel.
6. The units are now installed and operating.
7. Verify operation using the diagnostic LEDs. (See Figure 5).
NOTE
The LEDs only illuminate when there is signal traffic and are not illuminated during signal "quiet" times.
The LEDs may "flicker". This is normal operation.
APPLICATION NOTE
The Point-to-Point concept can be used to create an "optical bus" network. This can be useful for those
situations where the software in the Master has not been written in such a way that it can handle the return
of the transmitted echo that occurs in loop networks.
Figure 7 shows the connection scheme for an RS-232 optical bus.
Note that all Slaves hear the Master's transmission but only the Master hears the response from the
addressed Slave. The Master must always be the first IED in the network.
RS 232 Master / Slave
Last Slave
TR
COM
235
ON
OFF
Typical Slave
TR
COM
235235
ON
OFF
ON
OFF
Master
TR
COM
235ON
OFF
FIGURE 7. RS-232 Bus Configuration

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
2-4
APPLICATION NOTE
Another variation of the point-to-point concept, is the Optical Star network. This topology may be created
using the Dymec Optical Star OS5 or OS9. This topology creates a “Hub and Spoke” configuration which
can be useful in solving a network configuration based upon the physical positioning of the nodes.
The Dymec Optical Stars can also be used to create a multi-drop Master / Slave Optical Star network. The
Model 5843HRT and 5844HRT are optically compatible with the OS5 and OS9 Master and Slave ports. Figure
9 shows a typical connection of an Optical Star network.
The master IED must always be connected to the Master port of the Optical Star. The slave IED’s must always
be connected to the Slave ports of the Optical Star.
Variations of this configuration are as follows:
•The optical star may be the last node of an optical bus configuration. One may create an Optical Bus
configuration starting with the Master IED to a series of Slave IED’s and then connect the fiber network to
the Master port of the OS5 or OS9 to continue the network in a “Hub and Spoke” topology.
•A Master IED may be connected to the master port of an OS5 or OS9 and then an Optical Bus network
may be created from any Slave Port of the Optical Star.
•The Optical Stars maybe “cascaded”. Cascading means optically connecting a Slave Port of one Optical
Star to the Master Port of the next Optical Star.
•IED’s of different electrical formats (i.e., RS-232, EIA 422, EIA 485 2-wire or EIA 485 4-wire) may also be
interconnected optically in the Star Configuration. Models 5845HRT and Models 5846HRT are optically
compatible with the 5843HRT and 5846HRT and are used to serve to serve the EIA 422 and EIA 485
devices.
NOTE
It is not recommended that a “loop network” be connected to an Optical Stars Slave Port

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
2-5
MODEL OS5 FIBER OPTIC STAR
MODEL OS5 FIBER OPTIC STAR
Master
IED
TR
Slave
IED
TR
Slave
IED
TR
Slave
IED
TR
Slave
IED
TR
Slave
IED
TR
Slave
IED
TR
Slave
IED
TR
FIGURE 9. Optical Star Configuration
(OS5 cascaded to an OS5)

Models 5843, 5844, 5843S and 5844S
RS232 or TTL
2-6
2.2 LOOP OPERATION - MASTER/SLAVE CONFIGURATION
NOTE
Before constructing a loop network, be sure that the software protocol of the Master is capable of managing
the receipt of its own, echoed transmission. If it cannot, then use Point-to-Point configurations only between
devices in an "optical bus" network approach.
This configuration supports a system that requires more than two IED’s to be communicating. In a
Master/Slave loop system, one IED acts as a Master at all times and addresses or "polls" each of the other
connected IED’s individually. Each Slave receives the same transmission from the Master IED but only
responds when it recognizes its address in the polling message.
235
Master
TR
COM
ON
OFF
23 5
Slave
TR
COM
ON
OFF
23 5
Slave
TR
COM
ON
OFF
23 5
Slave
TR
COM
ON
OFF
FIGURE 8. Master/Slave Loop Configuration
The Master must have its Repeat Switch in the "OFF" position. When it transmits a request out its T optical
port, it will receive the echo of its request at its R optical port. This request has gone around the loop, and has
been repeated by each Slave in the loop. However, the Master does not repeat (re-transmit) any of these
received signals optically back around the loop, because its Repeat Switch is in the "OFF" position.