Description
Modicon AS-S908-120RP | S908 Remote I/O Cable Connector Kit
Product Introduction
When a sprawling legacy industrial network starts dropping packets due to impedance mismatches on aging coaxial runs, hunting down exact-match termination hardware stops minor glitches from cascading into total plant shutdowns. The AS-S908-120RP is not a generic consumer-grade RF adapter; it is an engineered-to-spec communication accessory built specifically for Modicon S908 remote I/O loops. It maintains proper signal reflection control across distributed drop drops without introducing line attenuation.
Designed to interface smoothly with standard twinaxial or coaxial S908 cabling architectures, this unit ensures reliable token-passing integrity—though your ultimate signal-to-noise ratio will vary depending on cable shield grounding and total run length. It provides an exact-fit replacement to keep vintage automation networks operating without a costly architecture overhaul.
AS-S908-120RP
Key Technical Specifications
| Parameter | Specification Metric |
| Accessory Type | S908 Remote I/O Network Connector / Terminator |
| Impedance Rating | 120 ohms nominal match |
| Network Compatibility | Modicon Remote I/O Coaxial Bus |
| Construction Material | Heavy-duty machined alloy shell with gold-plated pins |
| Environmental Rating | Standard industrial cabinet tolerance (0°C to 60°C) |
| Mounting Type | Direct cable or drop-tap attachment interface |
| Weight Envelope | Lightweight industrial component (~0.2 kg) |
Application Scenarios & Pain Points
- Automotive Body Shop Drop Lines: In high-vibration manufacturing zones where continuous mechanical flexing loosens standard commercial connectors, the locking mechanism and heavy shielding of the AS–120RP prevent intermittent bus drops.
- Continuous Chemical Processing Plants: Legacy control loops spread across vast acreage rely on precise 120-ohm bus termination to eliminate signal reflections that would otherwise corrupt remote register polling.
- Water Treatment Facility Network Refurbishment: When replacing degraded field taps on an aging backbone, using verified OEM connectors ensures immediate network synchronization without re-tuning communication parameters.
QA & Live Testing SOP (Trust Signal)
We treat vintage network accessories with strict physical and electrical inspection protocols. Before an AS–120RP ships from our inventory, it goes through a rigorous verification checklist:
- Visual & Dimensional Audit: Inspected under magnification for pin straightness, gold-plating continuity, thread integrity, and zero oxidation on shielding surfaces.
- Impedance & Continuity Testing: Measured on dedicated RF test benches to confirm precise resistance and impedance matching parameters against OEM specifications.
- Mechanical Fit Check: Trial-fitted against standard interface ports to ensure smooth engagement and secure locking behavior.
- Protective Packaging: Sealed in anti-static moisture-barrier bags and padded to prevent transit damage to delicate contact pins.
Field Engineer’s Pitfall Guide
- ❗ Impedance Mismatch Errors: Never substitute a standard 50-ohm commercial connector or generic terminator on an 120-ohm loop; doing so will cause severe signal reflections and trigger network-wide communication faults.
- ❗ Shield Grounding Failures: Ensure the outer shield drain makes 360-degree contact with the connector shell. Leaving the shield ungrounded in high-EMI environments turns the cable into an antenna for noise.
- ❗ Over-Torquing Threads: Avoid using wrenches or excessive force when tightening coaxial screw fittings; stripping the threads will ruin the drop interface and require complete cable re-termination.
Intent-Driven FAQ
Is this an original Modicon OEM part or an aftermarket copy?
This is a genuine legacy Schneider Electric / Modicon component, sourced as verified industrial surplus to ensure exact mechanical and electrical compatibility with your existing network.
What is the primary purpose of this component on an network?
The AS–120RP provides correct physical layer connection and impedance termination, preventing data-corrupting signal reflections at the ends of the remote I/O coaxial bus.
Can this component be used on standard Ethernet networks?
No. This hardware is specifically engineered for Modicon coaxial remote I/O architectures and is completely incompatible with standard IEEE 802.3 Ethernet protocols.
What causes intermittent communication drops on an bus?
Intermittent drops are typically caused by loose connector pins, oxidized contact surfaces, damaged coaxial shielding, or improper line termination. Inspecting and replacing worn connectors usually resolves the fault.
