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Fiberlink® 5018A User’s Manual
Fiberlink® 5018A
Operation Theory
Theory of Operation
The transmitting section of the universal data transceiver converts an incoming RS-232,
RS-422 or RS-485 signals into pulses of light at the transmitting LED located in the “Transmit
(or Tx)” optical connector on the unit. These pulses of light equate to ON for a positive input
level and OFF for a negative or zero input level.
The receiving section of the universal data transceiver produces a user selectable RS-232,
RS-422 or RS-485 compatible output from the received light at the photodiode located in
the “Receive (or Rx)” optical connector on the unit. Due to the fact that all internal logic
signals are converted to either light-on or light-off, any protocol may be used in conjunc-
tion with any other protocol, thereby allowing the transceiver to be used as a data
converter as well as a general data transceiver. In addition, provision is incorporated to
allow drop and repeat operation with any protocol.
During normal operation, the RTS line (terminal block position 6) is not used. In external
RTS operation (for RS-485), terminal block position 6 is used as an enable input to toggle
the unit between transmit and receive. In this mode a positive input switches the unit to
the transmit mode while a zero input switches the unit to the receive mode. As an alter-
native, the unit may be automatically switched from transmit to receive by means of an
internal data-driven timer (Data-Derived T/R switching).
1
2
3
6
LED Driver
Current/Voltage
Converter
Transmit
LED
Receive
Photodiode
UNIVERSAL DATA TRANSCEIVER BLOCK DIAGRAM
Protocol Converter
4
5
Signal
Terminal Block
