Description

Key Technical Specifications

Ports: 6x 10/100BaseT(X) RJ45, 2x 100BaseFX SC Multimode Fiber
Network Standards: IEEE 802.3, IEEE 802.3u, IEEE 802.3x
Fiber Mode: Multimode
Management Type: Unmanaged (Plug-and-Play)
Redundancy Protocol: None (No ring redundancy support)
Input Voltage: 24VDC (12-48VDC range), Redundant Dual Inputs
Relay Output: Yes (Power failure and port break alarm)
Dimensions (W x H x D): 53.6 x 135 x 105 mm (2.11 x 5.31 x 4.13 in)
Weight: 0.63 kg (1.39 lbs)
Operating Temperature: -10 to 60°C (Standard); -T models available for -40 to 75°C
Mounting: DIN-Rail or Panel Mount

Product Introduction

The MOXA EDS-308-MM-SC is an 8-port unmanaged industrial Ethernet switch designed to bridge copper and fiber networks in factory automation environments. It provides a direct hardware solution for connecting PLCs, HMIs, and sensors over long distances using its dual SC multimode fiber ports.Unlike standard commercial switches, this unit features rugged metal housing (IP30) and redundant 12-48VDC power inputs to prevent single-point power failures. While it lacks complex managed features, it includes a practical relay warning output that triggers immediately if the primary power supply fails or a specific port connection drops—saving maintenance teams hours of manual cable tracing.

Installation & Configuration Guide

Phase 1: Preparation (5 min)

Verify you have a 24VDC power source capable of supplying at least 0.5A.
Ensure your DIN rail is grounded according to local electrical codes.
Have a flathead screwdriver ready for the terminal block.

Phase 2: Removal (If replacing an old unit)

Disconnect the power wires from the 6-pin terminal block first.
Use a flathead screwdriver to gently pry the bottom clip of the switch upward to release it from the DIN rail.
Unplug all Ethernet and fiber cables. Tip: Take a quick photo of the wiring layout before disconnecting anything.

Phase 3: Installation (10 min)

Hook the top clip of the EDS-308 onto the DIN rail.
Press the bottom of the unit firmly until it clicks into place.
Insert your power wires into the V+ and V- terminals (PWR1 and PWR2). Tighten the screws securely.
Connect your RJ45 cables to ports 1-6 and your SC fiber patch cords to ports 7-8.

Phase 4: Power-On & Test (5 min)

Turn on the 24VDC power supply.
Check the “PWR” LED—it should be solid green. If it’s off, check your polarity.
Observe the link/activity LEDs on the connected ports. A blinking amber/green light indicates active data transmission.

Troubleshooting Quick Reference

Issue	Likely Cause	Quick Fix
PWR LED is OFF	No power or loose wire	Measure voltage at the terminal block; ensure it reads between 12-48VDC.
Fiber Link LED OFF	TX/RX reversed or bad cable	Swap the TX and RX fibers at one end. Check for visible breaks in the cable.
Intermittent Connection	Broadcast storm or bad port	Unplug other devices to isolate the issue. This switch has broadcast storm protection, but loops can still cause lag.
Relay Alarm Triggered	Power loss or cable cut	Check if one of your redundant power supplies failed or if an Ethernet cable was unplugged.

Dimensions, Mounting & Wiring Notes

Physical Size: The unit is compact at 53.6 mm wide, making it suitable for tight control cabinets.
Mounting: Designed primarily for 35mm DIN-rail mounting, but panel-mount kits are often sold as optional accessories.
Wiring Terminals: Uses a removable 6-pin terminal block for power and the relay alarm. The relay contact rating is typically 1A @ 24VDC.
Fiber Distance: With standard multimode fiber, you can expect reliable transmission distances up to 2 km (verify exact distance based on your specific fiber grade).

FAQ

Q: Can I use this switch to create a redundant fiber ring network?
A: No. The EDS-308-MM-SC is an unmanaged switch and does not support ring redundancy protocols like Turbo Ring or RSTP. If you need a self-healing network topology, you will need to look at MOXA’s managed EDS-400A or EDS-500 series.Q: Does this model support PoE (Power over Ethernet)?
A: No, the standard EDS-308-MM-SC does not provide PoE output. If your cameras or sensors require PoE, you would need the specialized EDS-P308 series or external PoE injectors.Q: What is the difference between the MM-SC and SS-SC versions?
A: The “MM” stands for Multimode fiber (supports distances up to ~2km), while “SS” stands for Single-mode fiber (supports much longer distances, typically 20km+). Make sure your fiber cabling matches the switch model.Q: I plugged it in, but the Fault LED is on. Is it broken?
A: Not necessarily. The Fault LED usually lights up if the relay alarm is triggered—for example, if you only connected one power supply but didn’t configure the DIP switch to ignore the second missing input. Check your power connections first.Q: Is this considered “New Surplus” or refurbished?
A: We supply this as New Original (New Surplus) in factory-sealed packaging. It has never been installed in a live environment, though the box may show minor shelf wear from warehouse storage.