Description
Product Introduction
The Schneider Electric Modicon AS-S908-120RP is a specialized coaxial cable repeater module engineered for legacy Modicon S908 Remote I/O networks. Operating as a critical network extension tool, this hardware layer boosts, isolates, and re-clocking communication data streams between central processors and remote drop locations across expansive industrial facilities.
Within large-scale distributed control architectures, the AS-S908-120RP prevents signal attenuation over long cable runs and mitigates electrical noise interference. Unlike standard drop adapters, this repeater provides essential bus isolation, ensuring that a physical fault or short circuit on one section of the coaxial network does not cascade and take down the entire distributed I/O framework.
Key Technical Specifications
| Parameter | Value |
| Product Line | Modicon S908 Remote I/O Network |
| Module Type | Coaxial Cable Repeater Module |
| Communication Protocol | S908 Remote I/O (Peer-to-Peer / Master-to-Drop) |
| Transmission Medium | 75-ohm Coaxial Cable (RG-6 / RG-11 equivalent) |
| Isolation | Galvanic signal isolation between network segments |
| Power Requirements | Powered via rack backplane or external DC supply |
| Diagnostic Indicators | Front-panel communication status and power LEDs |
| Operating Temperature | 0 °C to 60 °C (32 °F to 140 °F) |
| Enclosure Type | Standard Modicon 800 / Compact rack-mountable module |
Application Scenarios & The “Trench” Experience
Picture this: It is 1:00 AM at a sprawling petroleum tank farm. Suddenly, a remote pump station a mile away drops off the control network, triggering an emergency communication fault on the central Modicon PLC. Troubleshooting reveals that a lightning strike near an outdoor conduit run degraded the S908 coaxial signal below usable thresholds, paralyzing remote valve feedback loops. You cannot halt operations across the entire tank farm for a massive network redesign. You pull a pre-tested AS-S908-120RP repeater off the shelf, insert it into the local drop enclosure to recondition the signal strength, and bring the remote I/O link back online in minutes.
- Large-Scale Water & Wastewater Plants: Extending S908 coaxial network runs between distant lift stations and the main control building.
- Petroleum Tank Farms & Refineries: Bridging long-distance communication loops across sprawling outdoor processing units.
- Heavy Manufacturing Complexes: Maintaining robust remote I/O drop communications across multi-acre production floors with high electromagnetic interference.
Transparency SOP: Quality Assurance & Testing
We don’t just ship boxes; we test them on actual Modicon network rigs. Every surplus AS-S908-120RP unit goes through a rigorous verification process before leaving our warehouse:
- Inbound Inspection: Physical check for connector integrity, anti-counterfeit markings, and OEM seal inspection.
- Live Rig Testing: Installed into an active S908 network test loop to verify packet regeneration, baud rate stability, and error-free frame transmission.
- Signal Attenuation Simulation: Testing repeater performance under simulated long-run cable attenuation to ensure proper threshold boost.
- Firmware & Revision Logging: Verifying internal hardware revisions and logging serial numbers against QA records.
- Final QC & Anti-Static Packaging: Coaxial port capping, anti-static shielding, and high-density foam packing.
AS-S908-120RP
AS-S908-120RP
The Veteran’s Tech Trap Guide (Crucial Value-Add)
- ⚠️ Turn Off Rack Power First: Never insert or remove the AS-S908-120RP while the chassis backplane is energized. Hot-swapping network interface modules on legacy racks can corrupt communication registers and crash the active PLC processor.
- ❗ Coaxial Termination Impedance: Always verify that your coaxial network segments maintain proper 75-ohm termination resistors at both physical ends. Mismatched impedance or missing terminators will cause signal reflections that trick the repeater into flooding the bus with CRC errors.
- ⚠️ Ground Loop Isolation: Ensure that cable shields are grounded correctly at designated single-point panel locations. Grounding shields at both ends creates ground loops that introduce severe noise into the S908 data stream.
Frequently Asked Questions (FAQ for Conversion)
Q: Is the AS-S908-120RP hot-swappable?
A: No. Legacy Modicon S908 network racks do not support live insertion. Always power down the rack before servicing network modules.
Q: Are these units brand new or refurbished?
A: Our inventory consists primarily of New Surplus and Factory Sealed stock sourced from global industrial liquidations. Every unit undergoes live network loop testing prior to shipment.
Q: Why is your price lower than direct OEM channels?
A: Schneider Electric transitioned the S908 remote I/O network architecture to legacy status years ago. Authorized channels charge heavy lifecycle management markdowns to push full-system migrations. We supply certified surplus hardware to keep legacy networks running reliably without forced capital overhauls.
Q: What warranty is included with purchase?
A: Every AS-S908-120RP ships with our comprehensive 12-month replacement warranty.
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