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Fiberlink® 5018A User’s Manual
Fiberlink® 5018A
Configuring a Ring or Loop-Type Data Bus
In addition to point-to-point transmissions, the universal data transceiver can be used to
implement a ring or loop-type data bus. This is accomplished by setting the internal DIP
switches as shown in the following diagram.
When the Universal Data Transceiver is used in this mode, any location can receive or insert
data into the ring/loop but only one station at a time is permitted to insert data. All other
stations will receive the data but
must
maintain their individual input lines in the low state
(RS-232, terminal block position 2 negative with respect to position 1; RS-422, terminal
block position 2, negative with respect to position 3) to prevent loop lock-up. RS-485
operation does not have the above restriction due to the fact that it is in the tri-state mode
when not transmitting.
Note that the first (or host) location is set to the point-to-point mode. All other locations are
set to the drop-and-repeat mode. This is to prevent loop lock-up or data “echos”.
Configuring a Ring or Loop Data Bus
Fiber Optic Cable
Data Flow
Fiber Optic
Transceiver
To Host Computer
Set to point-to-point
mode of operation
Set to drop-and-repeat
mode of operation
Ring or Loop-Type Data Bus Configuration
Set to drop-and-repeat
mode of operation
Set to drop-and-repeat
mode of operation
Drop 3
Drop 2
Drop 1
Fiber Optic
Transceiver
Fiber Optic
Transceiver
Fiber Optic
Transceiver
Data Flow
Data Flow
Data Flow
