Product Description
Industrial Serial to Fiber Optic Converter – 1 Core Single-Fiber, Used in A/B Pairs(ใช้งานเป็นคู่) ราคาต่อตัว
A Type (1310/1550nm) TX
The Bismon B1-DIDUSS-20A Single-Fiber is an industrial-grade RS232/RS485/RS422 to fiber optic converter designed for long-distance serial data transmission.
Its key advantage is full bidirectional communication over a single fiber core using WDM (Wavelength Division Multiplexing) technology.
The converters work as a matched pair: A side transmits at 1310nm / receives at 1550nm, and B side transmits at 1550nm / receives at 1310nm.
This saves up to 50% of fiber cores, making it ideal for existing cables with few spare cores or leased fiber billed per core.
It supports a standard transmission distance of 20km over 9/125µm single-mode fiber.
Data is transmitted transparently, with automatic baud rate detection from 300bps to 115200bps – no configuration required.
RS485 data direction is controlled automatically without RTS/DTR signals, supporting up to 128 nodes.
Fiber transmission eliminates the EMI, ground loop and lightning damage problems common to long copper serial lines.
The unit accepts DC 5–36V with reverse polarity protection, in an IP40 metal housing rated for -40°C to +85°C.
Ideal for PLC, SCADA, energy meters, building automation, access control, parking systems and toll station applications.
Why Choose Single-Fiber for RS485 to Fiber Systems?
Industrial RS485 traffic is low-bandwidth (up to 115.2kbps) but often has to travel long distances between buildings, substations or field equipment. Dedicating two fiber cores to such a small data stream wastes valuable cable capacity. Single-fiber technology makes far more efficient use of your fiber infrastructure.
| Item |
Dual-Fiber (2 Cores) |
Single-Fiber (1 Core) |
| Fiber cores per link |
2 cores |
1 core (50% saving) |
| Wavelength |
Same wavelength on both sides |
A: 1310/1550nm, B: 1550/1310nm |
| Leased fiber cost (per core) |
2× |
Half the cost |
| Connectors / loss points |
2 connectors per side |
1 connector per side |
| Risk of TX/RX crossover errors |
Yes |
None (single core) |
| Expansion on existing cable |
Limited |
Up to 2× more links |
| Installation |
Any two identical units |
Must use an A + B pair |
Features
| Feature |
Description |
| Single-Fiber WDM (BiDi) |
Bidirectional transmission over one fiber core |
| A/B Paired Operation |
A: TX 1310nm / RX 1550nm; B: TX 1550nm / RX 1310nm |
| 3-in-1 Serial Interface |
Supports RS232, RS485 and RS422 |
| Auto Baud Rate |
Automatic detection from 300bps to 115200bps |
| RS485 Auto Direction |
Automatic data flow control, no RTS/DTR required |
| Multi-Node Support |
RS485 up to 128 nodes |
| Long Distance |
20km standard over single-mode fiber |
| Wide Power Input |
DC 5–36V with reverse polarity protection |
| Industrial Grade |
IP40 metal housing, -40°C to +85°C |
| EMC Protection |
Compliant with IEC 61000-4-2 / 4-4 / 4-5 |
Functions
| Function |
How It Works |
| Serial to Fiber Conversion |
Converts RS232/485/422 electrical signals to optical signals over fiber |
| Transparent Transmission |
Passes data without protocol changes – works with Modbus RTU and other serial protocols out of the box |
| Wavelength Multiplexing |
Separates transmit and receive directions using 1310nm and 1550nm on one core |
| Point-to-Point / Point-to-Multipoint |
Connects master and slave devices in single or multi-point networks |
| Zero-Delay Conversion |
Internal conversion with no added latency |
| Status Monitoring |
LED indicators for PWR, RUN, TXD and RXD |
Benefits
| Benefit |
Value to Your System |
| 50% Fiber Core Saving |
Reuse existing cables with limited spare cores – no new cable runs |
| Lower Cost |
Reduces dark fiber lease, cable, splicing and connector costs |
| Easy Expansion |
Doubles the number of links your existing cable can carry |
| Simple, Error-Free Installation |
One connector per side – no TX/RX crossover mistakes |
| Fewer Loss Points |
Fewer connectors and splices for a more stable link |
| Surge & Lightning Immunity |
Non-conductive fiber fully isolates grounds between sites |
| EMI Immunity |
Reliable near motors, inverters and power cables |
| Plug-and-Play Compatibility |
No changes to existing PLC/SCADA software or hardware |
| Data Security |
Fiber is far harder to tap than copper cable |
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 RS232_485_422 to Fiber converter Industrial grade_6.webp)
Specifications
| Category |
Item |
Specification |
| Serial Port |
Standards |
EIA RS232, RS485, RS422 |
| Interface |
1× RS232 or RS485/422 |
| Connector |
RS232: DB9 female; RS485/422: 5-pin terminal block, 3.81mm pitch |
| RS232 Signals |
TX, RX, GND |
| RS485/422 Signals |
T+/A, T-/B, R+, R-, GND |
| Baud Rate |
300bps – 115200bps (auto-sensing) |
| Nodes |
RS485 up to 128 nodes |
| Direction Control |
RS485 automatic direction detection |
| Fiber Port |
Type |
1× single-fiber (BiDi WDM) |
| Connector |
SC (ST/FC optional) |
| Wavelength |
A side: TX 1310nm / RX 1550nm
B side: TX 1550nm / RX 1310nm |
| Fiber Type |
Single-mode 9/125µm |
| Distance |
20km (standard) |
| TX Power / Sensitivity |
≥ -8dBm / ≤ -20dBm (depends on optical module) |
| Bit Error Rate |
≤ 10-9 |
| Status LED |
Indicators |
PWR, RUN, TXD (fiber transmit), RXD (fiber receive) |
| Power |
Input Voltage |
DC 5–36V, reverse polarity protection |
| Power Consumption |
< 0.3W @ DC 24V (full load) |
| Connector |
2-pin 5.08mm terminal block or Φ2.5mm DC barrel jack |
| Physical |
Dimensions |
96 × 90 × 26 mm |
| Housing / IP Rating |
Metal, IP40 |
| Installation |
Wall-mounted |
| Weight |
Approx. 0.25kg |
| Environment |
Operating Temp |
-40°C to +85°C |
| Storage Temp |
-40°C to +85°C |
| Humidity |
5–95% (non-condensing) |
| EMC |
ESD |
IEC 61000-4-2 Level 4 (contact ±8kV, air ±15kV) |
| Surge |
IEC 61000-4-5 Level 3 (power & RS485: CM ±2kV, DM ±2kV) |
| EFT |
IEC 61000-4-4 Level 4 (power ±4kV, RS485 ±2kV) |