FiberPlex TD-7280 - Manual (Page 12)

Interface Details
Audio Connections
The audio path in the FOI(TD)‐7280 provides a high quality bi‐directional stereo audio pathway. Line level
analog inputs are sampled at 96KHz with 24 bit resolution. The inputs have a wide frequency response (20Hz ‐
45KHz) for maximum audio fidelity; however this wide range also accommodates ultra‐sonic signaling found in
some electronic devices including some Intercom systems. Interface Connector Pin 1‐6 compromise the
balanced audio inputs with channel 1 on Pins 1‐3 and channel 2 on 4‐6. For unbalanced, or single ended,
operation, set the ‘Ubal’ switch on the Configuration Switch (position 1) to the enabled, or up position. This
provides a +6dB boost to the signal to maintain unity gain. Unbalanced audio inputs can then be connected
using the ‘Plus’ and ‘Ground’ connections (Pins 2&3 and 5&6).
The analog audio outputs are found on Interface Connector Pins 13‐18 and are unity gain line level outputs
meaning whatever signal level you present to the corresponding remote input you will receive on the output.
Like the inputs, the audio outputs are balanced by default and can be turned in to unbalanced outputs by
enabling the ‘Unbal’ switch in the Configuration switch. Unbalanced audio outputs can then be connected
using the ‘Plus’ and ‘Ground’ connections (Pins 14&15 and 17&18).
BALUN
Two FOI(TD)‐7280 units connected via fiber can be used as a BALUN (Balanced / Unbalanced converter) by
leaving one unit set to ‘Balanced’ mode and the remote unit set to ‘Unbalanced’ mode.
Voltage Sensor for SCADA
The unique audio input and output design of the FOI(TD)‐7280 can accommodate DC voltages as well as
analog audio I/O. Certain sensors and transducers used in SCADA (Supervisory Control and Data Acquisition)
such as temperature sensors, pressure gauges, etc. report their status by using a variable DC Voltage output.
These devices can be connected directly to the audio path to transit this data via fiber to Remote Terminal
Units (RTUs) that may be some distance away.
Push To Talk (PTT)
With the ‘PTT’ switch enabled on Configuration Switch (position 2), the audio inputs of the unit are muted
until there is an activation of either the Shorting Activation (Interface Connector Pin 11) or the Negative
Voltage Activation (Interface Connector Pin 12). The audio will continue to be transmitted as long as one or
both of these pins remains active. When both pins are in the non‐active state, the audio will once again be
muted. There is more information in the PTT section of the Control Connections section later in the manual.
Serial Data Connections
The FOI(TD)‐7280 provides a highly flexible serial data interface. The serial data is ‘tunneled’ through the fiber
connection and presented to the I/O connector of the remote unit as if a null‐modem cable was connected.
The RX (data input) pins for serial interface can be found on Pins 7‐9 of the Interface Connector and the TX
(data output) pins can be found on Pins 19‐21. Configuration Switch ‘Serial Mode’ settings (positions 5‐6) are
used to define the physical configuration of the serial interface. See ‘Switch Settings’ in the ‘Getting Started’
section earlier in the manual for details.
Serial Termination
As dictated by the application, default serial line termination of 150KΩ can be removed by enabling the ‘Term’
switch on the Configuration Switch (position 8). This applies to RS‐422 and RS‐485 modes only.
RS‐232
With ‘Serial Mode’ setting on the Configuration Switch set to ‘off, off’, RS‐232 mode is enabled. In this mode,
physical connection are made on Interface Connector Pins 8&9 (RX) and 20&21 (TX). This is a standard RS‐232
interface with a maximum data rate of 1 Mbps with a 3K ohm load. Detailed electrical specifications of the
interface can be found in the specification table at the end of the manual.
RS‐422
With ‘Serial Mode’ setting on the Configuration Switch set to ‘off, on’, RS‐422 mode is enabled. In this mode,
balanced physical connection are made on Interface Connector Pins 7&8 (RX) and 19&20 (TX) with serial
ground reference on Pins 9&21. This is a standard RS‐422 interface with a maximum data rate of 1 Mbps.