PSI-MOS-RS485W2/FO 1300 E Serial to Fiber Converter
Connect 2-wire RS485 devices to fiber optic cable

- Extend serial data up to 28 miles
- Immune to EMI, RFI and transient surges
- Point-to-point or star configuration
- SC type fiber connectors
- Terminal Block for 2-wire RS485 Connections
The PSI-MOS-RS485W2/FO 1300 E can be used to convert RS485 2-wire devices to fiber optics. By transmitting serial data over optical fiber, these serial media converters provide an economical path to extend the reach of RS485 devices. All protocols with 10/11-bit UART data format and NRZ data coding are supported. This includes popular protocols such as:
- Modbus ASCII / MODBUS RTU
- SUCONET K
- S-BUS
- DH-485, and more…
Long Distance Serial Data Transmission over Fiber
RS485 Serial transmission is commonly limited to 100 kbps over a distance of only 1200 meters (4000 feet). Using the FO 1300 E Serial to Fiber Converter you can extend your serial data transmission up to 27km (16.7 miles) over multimode fiber or 45km (28 miles) over single mode fiber. The result is that any two pieces of asynchronous serial equipment, located miles apart, can communicate at half duplex over fiber optic cable at rates up to 500 kbps.
EMI, RFI and Transient Surge Immunity
Another advantage of the FO 1300 E fiber optic transmission system is the electrically isolated connection of devices. Electromagnetic interference (EMI) is a common phenomenon in typical environments like industrial plants, warehouses and factory floors. This interference can cause corruption of data over RS485 or copper-based Ethernet links. Data transmitted over fiber optic cable however is completely immune to this type of noise, thus preventing the negative effects of voltage equalization currents and electromagnetic interference on the data cables. A Serial to Fiber Media Converter therefore enables you to inter-connect your serial devices over fiber ensuring optimal data transmission, increased availability of the system, and improved network design flexibility for point-to-point connections and star structures.
Flexible Fiber Optic Connections
The FO 1300 E operates at 1300 nm wavelength, using a separate LED emitter and photo-detector on SC type connectors. Almost any multimode or single mode glass fiber size can be used.
Power Budget Considerations
Calculating the power budget is critically important with planning the fiber optic link. The optical power budget is the amount of light required to transmit data successfully over distance through a fiber-optic connection. The amount of light energy available within the setup will dictate the length of the fiber optic cable run between serial media converters within the network. Optical power budgets are critical to help businesses avoid signal distortion.To learn how to calculate optical power budget read our technical note. Transmit and receive dBm can be found in the Hardware specifications.
Transmit each serial signal out over 10 fiber optic lines
Up to ten (10) Serial to Fiber Converters can be grouped together using the TBUS DIN Rail bus system for voltage and data. This allows the serial converter to operate as a star coupler, taking the serial data input signal and distributing it to all Fiber optic output ports.
High Quality Features and Support
The FO 1300 E are also equipped with comprehensive diagnostic functions to increase system availability, simplify start-up and permanently monitor the optical transmission quality. The integrated optical diagnostics allow permanent monitoring of the FO paths during installation and operation. The floating switch contact is activated when the signal level on the fiber optic paths reaches a critical level. This early alarm generation enables critical system states to be detected before they result in failure. These cost and time saving features, along with free worldwide technical support, make the FO 1300 E serial to fiber converter the smart choice for IT professionals.
- Supply voltage and data signals routed through via DIN rail connectors
- Connections can be plugged in using a COMBICON screw terminal block
- Automatic data rate detection or fixed data rate setting via DIP switches
- Redundant power supply possible by means of optional system power supply unit
- High-quality electrical isolation between all interfaces (RS-485, fiber optic ports, power supply, DIN rail connector)
- Approved for use in zone 2
- Integrated optical diagnostics for continuous monitoring of fiber optic paths
- Floating switch contact for leading alarm generation in relation to critical fiber optic paths
- Suitable for data rates up to 500 kbps





PSI-MOS-RS485/FO 1300 E Technical Specifications
Ambient conditions | |
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Ambient temperature (operation) | -20 °C ... 60 °C |
Ambient temperature (storage/transport) | -40 °C ... 85 °C |
Permissible humidity (operation) | 30 % ... 95 % (non-condensing) |
Altitude | 5000 m (For restrictions see manufacturer's declaration) |
Degree of protection | IP20 |
Noise immunity | EN 61000-6-2:2005 |
Standards and Regulations | |
Electromagnetic compatibility | Conformance with EMC directive 89/336/EC |
Type of test | Vibration resistance in acc. with EN 60068-2-6/IEC 60068-2-6 |
Test result | 5g, 10-150 Hz, 2.5 h, in XYZ direction |
Type of test | Shock in acc. with EN 60068-2-27/IEC 60068-2-27 |
Test result | 15g, 11 ms period, half-sine shock pulse |
Shock | 15g in all directions in acc. with IEC 60068-2-27 |
Noise emission | EN 55011 |
Noise immunity | EN 61000-6-2:2005 |
Free from substances that could impair the application of coating | according to P-VW 3.10.7 57 65 0 VW-AUDI-Seat central standard |
Connection in acc. with standard | CUL |
Standards/regulations | EN 61000-4-2 EN 61000-4-3 EN 61000-4-4 EN 61000-4-5 EN 61000-4-6 |
Vibration (operation) | In acc. with IEC 60068-2-6: 5g, 150 Hz |
Conformance | CE-compliant |
ATEX | II 3 G Ex nA nC IIC T4 Gc X |
UL, USA/Canada | 508 listed 508 recognized |
Optical interface FO | |
Number of FO ports | 1 |
Wavelength | 1300 nm |
Transmission length incl. 3 dB system reserve | 25 km (With F-G 50/125 0.7 dB/km at 1300 nm) 22 km (with F-G 62.5/125 0.8 dB/km at 1300 nm) 45 km (With F-E 9/125 0,4 dB/km at 1300 nm) |
Transmission medium | Multi-mode fiberglass Single-mode fiberglass |
Transmission protocol | Protocol-transparent to the RS-485 interface |
Connection method | SC duplex |
General | |
Bit distortion, input | ± 35 % (permitted) |
Bit distortion, output | < 6.25 % |
Electrical isolation | VCC // RS-485 |
Test voltage data interface/power supply | 1.5 kVrms (50 Hz, 1 min.) |
Electromagnetic compatibility | Conformance with EMC directive 89/336/EC |
Noise emission | EN 55011 |
Net weight | 225.3 g |
Housing material | PA 6.6-FR |
Color | green |
MTBF | 484 Years (Telcordia standard, 25°C temperature, 21% operating cycle (5 days a week, 8 hours a day)) 102 Years (Telcordia standard, 40°C temperature, 34.25% operating cycle (5 days a week, 12 hours a day)) |
Conformance | CE-compliant |
ATEX | II 3 G Ex nA nC IIC T4 Gc X (Please follow the special installation instructions in the documentation!) |
UL, USA/Canada | 508 listed 508 recognized |
Digital outputs | |
Output name | Relay output |
Output description | Alarm output |
Number of outputs | 1 |
Maximum switching voltage | 60 V DC 42 V AC |
Limiting continuous current | 1:00 AM |
Power supply | |
Nominal supply voltage | 24 V DC (With UL approval) |
Supply voltage range | 18 V DC ... 32 V DC |
Max. current consumption | 90 mA |
Typical current consumption | 55 mA (24 V DC) |
Connection method | COMBICON plug-in screw terminal block |
Typical current consumption | 170 mA (According to UL Listed, 24 V DC) 110 mA (According to UL Recognized, 24 V DC) |
Serial interface | |
Interface 1 | RS-485 interface, 2-wire |
Operating mode | Semi-duplex |
Connection method | Pluggable screw connection |
File format/coding | UART (11/10 bit switchable; NRZ), slip-tolerant |
Data direction switching | Automatic control |
Transmission medium | Copper |
Transmission length | ≤ 1200 m (depending on the data rate, with shielded, twisted data cable) |
Termination resistor | 390 Ω 220 Ω 390 Ω (Can be connected) |
Conductor cross section solid min. | 0.2 mm² |
Conductor cross section solid max. | 2.5 mm² |
Conductor cross section flexible min. | 0.2 mm² |
Conductor cross section flexible max. | 2.5 mm² |
Conductor cross section AWG min. | 24 |
Conductor cross section AWG max. | 14 |
Serial transmission speed | 4.8/ 9.6/ 19.2/ 38.4/ 57.6/ 75/ 93.75/ 115.2/ 136/ 187.5/ 375/ 500 kbps |
Dimensions | |
Width | 35 mm |
Height | 99 mm |
Depth | 105 mm |
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Environmental Product Compliance | |
China RoHS | Environmentally Friendly Use Period = 50 |
Reach and RoHS Compliant | Reach and RoHS Compliant |
Approvals | |
cUL Listed cULus Listed UL Listed ATEX EAC DNV cUL Recognized cULus Recognized UL Recognized |
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Commercial data | |
Packing unit | 1 |
Weight per piece | 230.1 g |
Country of origin | Germany |
Warranty | 1 Year |
Classifications | |
eCl@ss 4.0 | 27230207 |
eCl@ss 4.1 | 27230207 |
eCl@ss 5.0 | 27230207 |
eCl@ss 5.1 | 27230207 |
eCl@ss 6.0 | 27230207 |
eCl@ss 7.0 | 27230207 |
eCl@ss 8.0 | 19179290 |
eCl@ss 9.0 | 19179290 |
ETIM 2.0 | EC001423 |
ETIM 3.0 | EC001423 |
ETIM 4.0 | EC001423 |
ETIM 5.0 | EC000310 |
ETIM 6.0 | EC000310 |
UNSPSC 6.01 | 30211506 |
UNSPSC 7.0901 | 39121008 |
UNSPSC 11 | 39121008 |
UNSPSC 12.01 | 39121008 |
UNSPSC 13.2 | 43222604 |
PSI-MOS-RS485/FO 1300 E Serial to Fiber Media Converter Applications |
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Point-to-point connections between serial devices over fiber |
You can use two PSI-MOS-RS485W2/FO 1300 E Serial to Fiber Converters to easily convert a data link from copper cable to fiber optics.![]() |
Linear Networks |
The PSI-MOS-RS485W2/FO 1300 E device can be used to network several RS-485 devices to form a linear structure. Devices are used in conjunction with DIN rail connectors along the line.![]() |
Star structures |
You can network RS-485 2-wire devices within a star structure. Depending on the number of star lines required, several PSI-MOS-RS485W2/FO 1300 E Serial to Fiber Converters are connected to TBUS DIN Rail bus systems for voltage and data. This makes up to 10 fiber optic ports available. Cross-wiring for serial data and for the supply voltage is provided automatically by the DIN rail connector.![]() |
Tree structures |
Linear and star structures can be cascaded to create complex tree structures. The number of devices that can be cascaded is only limited by the timing response (timeout) of the bus system used due to the bit retiming of the PSI-MOS-RS485W2/FO 1300 E fiber optic converter.![]() |
Block Diagram |
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