Universal serial RS232/RS422/RS485 to single-mode optic fiber media converter (2 SC type connectors )

NOTE : RD320-OF has reached the end of its life cycle (to know more about its different deadlines click here).


  • 3 in 1 built-in serial interface : RS232/RS422/RS485, speed up to 500 Kbps (RS232), 2 Mbps (RS422/485)
  • Reliable error free communication even in case of EMI/RFI pertubations
  • Fiber length up to 20 Km (9/125 µm fiber type), SC type connectors
  • Automatic RS485 line turn-around, software independent
  • Half-duplex & Full-duplex bidirectionnal data transmission
  • Activity LED for fiber and copper TxD & RxD signals, error LED in case of fiber breakdown
  • Wide DC power range, from +9VDC to +36VDC
  • Point to point mode
  • 15 KV ESD protection and HF filtering on the copper side
  • Robust & compact metal case, CE standards, 35 mm Din Rail mounting


Using fiber optic enables to use a higher communication bandwidth while offering a total immunity against EMI/RFI interferences and an increased security as well.

The optical fibre still offers other advantages : use without risk in an explosive environment, no EMC emission, no ground loops, immunity against lightning and high voltage environments, they are finally lighter, less cumbersome, inert and corrosion resistant ...

Plug & Play: RD320 device features a self configuration mechanism based on a CPLD component that frees you from the tiresome operation which consists in the serial parameters setup, product is "Plug & Play".

RD320 features in standard a built-in system to control the fiber integrity, it reports automatically any failure with an error LED and also setups a relay contact (MOSFET) to activate any external safety device.

Its small size, design features and its great adaptability make the RD320 a really universal product capable to satisfy to major needs of the industry.


Technical characteristics





Serial RS232/RS422/RS485 to single-mode fiber optic, RS485 mode self line turnaround




Serial speed


500 Kbps for RS232 mode, 2Mbps for RS422/RS485 mode






20 Km with a 9/125 µm fiber type at 25°C




Serial protocols


The device supports any kind of communication protocols (Modbus, Unitelway, Profibus, DH+ and any ASCII or binary serial protocols ...)






Serial link parameters auto configuration, no switches. Line polarization, termination and selection between RS232/RS422/RS485 modes are configurable by mini-switches.




Serial connectors


Pluggable screw-in terminal, TxD & RxD signal for RS232 mode, TxA, RxA, TxB, RxB for RS422 mode, TRxA & TRxB for RS485 mode




Optic fiber


9/125 µm fiber support, 1310 nm wave length




Power budget


16 dB (typical)




Fiber connectors


2 SC connectors




Network topologies


Point to point, ring






2 LEDs Tx/Rx for copper

2 LEDs Tx/Rx for fiber optic n°1

1 LED for fiber n°1 breakdown

1 LED for power






31 RS485 interfaces, 10 RS422 interfaces




Input load


Input load 1/8 UL in RS485 mode




EMI/RFI protection


Built-in continuous line surge protection, ESD protection (15 KVeff), HF filtering






Infinite galvanic isolation through the optic fiber






NF EN 55022 emission, NF EN 61000-6-2 immunity






Fiber breakdown self diagnostic, failure is reported on a LED and a relay contact (MOSFET) is activated.




Power supply


+9VDC to +36VDC (pluggable screw-in terminal), 2.5W






Temperature from -5°C to +65°C, storage -40°C to +80°C, relative humidity from 0 to 95% RH without condensation




Dimensions, weight


107 mm (L) x 88 mm (l) x 25 mm (H), 260 g



Point to point topology

This configuration enables to control a single equipment installed in a very polluted or distant area. The optical line is totally insensitive to EMI/RFI perturbations.

Application RD320-OF_1

Simple ring topology

This topology enables to build a simple ring whereas the master equipment is installed in the middle.

Application RD320-OF_2

Technical documentation

NOTE : RD320-OF has reached the end of its life cycle (to know more about its different deadlines click here).

Reference to order





Serial RS232/RS422/RS485 to single mode fiber optic media converter, +9VDC to +36VDC power supply, din rail mounting