Description
The Phoenix Contact PSI-MOS-PROFIB/FO 850 T (Order No. 2708614 typical for T-version) and PSI-MOS-PROFIB-FO 850 T-SO are active PROFIBUS-to-Fiber-Optic media converters (FO converters) that allow you to extend PROFIBUS DP / PA networks over glass fiber (multimode or single-mode per variant) with galvanic isolation, EMI immunity, and extended range (up to 15 km with single-mode fiber).
They convert the electrical PROFIBUS RS-485 signal (9.6 kbps – 12 Mbps, auto-baud detection) to an optical signal transmitted via 850 nm multimode fiber (ST or BFOC/2.5 connectors — check suffix) or optionally single-mode (1310 nm — other PSI-MOS variants). The “T” indicates a Terminating (Terminal) resistor built-in for the PROFIBUS electrical side (can be activated via DIP switch), simplifying bus termination at the fiber-optic node. “SO” in some suffixes refers to Single-Option or Special Order packaging / wavelength variant.
These converters are DIN-rail mounted, require 24 V DC, and are fully transparent to the PROFIBUS master — no software configuration needed.
Key Features
- Protocol Transparency: Fully transparent to PROFIBUS DP/PA — no addressing, no GSD file.
- Baud Rate: Auto-detect 9.6 kbps … 12 Mbps (PROFIBUS DP max).
- Fiber Type: Multimode 50/125 µm or 62.5/125 µm (850 nm) — typical for PSI-MOS-PROFIB/FO 850 T; single-mode 1310 nm available in other PSI-MOS models.
- Reach: Up to 2 km (multimode 50/125 µm typical); single-mode variants up to 15 km.
- Built-in Terminator (T-version): DIP-switch selectable 220 Ω termination resistor on PROFIBUS side.
- Diagnostics: Power LED, Rx/Tx LEDs for electrical & optical sides.
- Country of Origin: Germany
Model & Variant Reference
Model / Ref. | Fiber Type & Wavelength | Connector | Built-in Term.? | Notes |
|---|---|---|---|---|
PSI-MOS-PROFIB/FO 850 T (2708614) | Multimode 850 nm | ST (straight tip) typical | ✅ Yes (DIP-switch) | Most common PROFIBUS-over-MMFiber conv. |
PSI-MOS-PROFIB-FO 850 T-SO | Multimode 850 nm (Special Opt. / SO pkg) | ST or BFOC (check) | ✅ Yes | Often same electrically; “-SO” = special packaging/wave variant |
Single-Mode Variant | Single-Mode 1310 nm | ST/SC/LC (var.) | ✅ (T-ver.) | For long-haul (up to 15 km) — different order no. (e.g., PSI-MOS-PROFIB-SM…) |
⚠️ Important Installation Notes:
Always Use in Pairs: One at each end of the fiber link — electrical PROFIBUS segment → FO Conv → Fiber → FO Conv → electrical PROFIBUS segment. Fiber Continuity: Ensure fiber continuity (Tx → Rx crossed: Converter A Tx → Converter B Rx). Use fiber light source/power meter if link fails. PROFIBUS Segment Length: The electrical segments on either side still count toward PROFIBUS max segment length (100 m @ 12 Mbps; 1200 m @ 9.6 kbps). The fiber link itself is NOT part of the RS-485 segment length limit. Termination: Activate the built-in terminator (DIP on T-version) ONLY at the physical ends of the electrical PROFIBUS segment — not in the middle. Connector Polish: Use correct polish (typically PC/UPC for multimode ST).
Technical Specifications (Representative — PSI-MOS-PROFIB/FO 850 T, 2708614)
Parameter | Specification |
|---|---|
Model / Order Code | PSI-MOS-PROFIB/FO 850 T (Phoenix Contact 2708614) |
Function | PROFIBUS RS-485 ↔ Multimode Fiber-Optic Media Converter |
Supported Protocol | PROFIBUS DP (9.6 k – 12 Mbit/s), also works with other RS-485 async (Modbus RTU, etc.) |
Electrical Interface (PROFIBUS side) | RS-485, 9-pin D-Sub (female) — pinout per PROFIBUS standard (A = Data-, B = Data+, GND, +5V unused) |
Termination Resistor | 220 Ω (switch-activated on T-version) |
Optical Interface | Multimode 850 nm, ST connector (female) — typ. 50/125 µm or 62.5/125 µm fiber |
Max. Fiber Length (Multimode) | 2 km (50/125 µm GI-MMF); 1 km (62.5/125 µm typical) |
Supply Voltage | 18–30 V DC (typical 24 V DC), reverse polarity protected |
Current Consumption | ≤ 150 mA @ 24 V DC |
Indicators | PWR (green), Rx/Tx Electrical (yellow), Rx/Tx Optical (yellow/orange) |
Mounting | 35 mm DIN rail (EN 60715) — plug-in housing |
Dimensions (W×H×D) | 45 mm × 99 mm × 114 mm (approx.) |
Weight | ~ 0.25 kg |
Operating Temp. | 0 °C to +55 °C (some -T versions -20 °C to +60 °C — check data sheet) |
Standards | CE, UL 508, cULus, RoHS |
Warranty & After-Sales
- Factory new units: 12 months warranty
- Refurbished units: 3-6 months warranty
- Technical support for:
- DIP-switch setting (termination ON/OFF, baud display)
- Fiber type & connector matching (MM vs SM, ST vs SC/LC)
- PROFIBUS segment rules (electrical segment length still applies on both sides)
- LED diagnosis interpretation (no optical link = check fiber continuity / Tx↔Rx cross)
- Cross-reference vs. Hirschmann OZD / Pepperl+Fuchs Visolux PROFIBUS FO converters
Delivery Time
- Standard delivery: 3-5 working days (stock items)
- Express shipping available upon request
Why Choose Our Store
- Genuine Phoenix Contact components
- Global supply network with competitive pricing
- Expertise in PROFIBUS network design (fiber segments, repeaters, diagnostics)
- Comprehensive technical documentation (pinout, DIP-switch defaults, fiber loss budget guide)
- Responsive customer service and support
Applications
- PROFIBUS DP extension across electrically noisy areas (near VFDs, welders)
- Inter-building PROFIBUS links with ground potential differences (fiber provides galvanic isolation)
- Redundant ring topologies (with PSI-MOS repeaters in ring — consult for ring redundancy)
- Protecting master/slave nodes from ground loops & surge via optical isolation
- Retrofit copper-only PROFIBUS segments to fiber for EMI immunity





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