GarettCom 5843HRT User Manual page 6

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.
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.
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.
Multi-mode units are economical and effective for transmission over
1-2
Models 5843, 5844, 5843S and 5844S
RS232 or TTL
All loop