Mitsubishi FX0N-8EYR PLC Expansion Module – MELSEC FX0N

Mitsubishi FX0N-8EYR — 8-Point Relay Output Expansion Module for MELSEC FX0N Control Systems

The FX0N-8EYR is a dedicated relay output expansion unit within Mitsubishi Electric’s MELSEC FX0N platform. It extends the discrete output capacity of any FX0N base CPU by eight independently switched relay contacts, each rated at 2 A. In a control architecture where the base unit’s onboard I/O is fully committed to process inputs and high-speed transistor outputs, the FX0N-8EYR absorbs the remaining load-switching duties — solenoid valves, motor starter coils, indicator lamps, and alarm horns — without burdening the CPU’s internal power bus or consuming transistor output channels that carry timing-critical signals.

The module connects directly to the FX0N expansion bus via a dedicated side connector, drawing logic power from the base unit. No external 24 V supply wiring to the module itself is required; only the load-side wiring to each relay output terminal is field-installed. This architecture keeps cabinet wiring lean and reduces the number of potential failure points in the output circuit.

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Technical Parameters

Hardware Logical Analysis

The FX0N-8EYR’s relay output stage is built around eight independent electromechanical relay elements, each driven by a dedicated transistor driver circuit on the module’s internal PCB. The driver transistor receives its switching signal from the FX0N expansion bus, which carries the CPU’s output image data refreshed every scan cycle. The relay coil is energized through an onboard flyback suppression diode, clamping the inductive kickback voltage to within safe limits for the driver transistor — a detail that directly affects long-term driver reliability in applications with high relay switching frequency.

EMC Design: The relay contact circuit is galvanically isolated from the logic bus. The isolation barrier between the 5 V logic side and the load-side contact sits at the relay coil/contact boundary, providing inherent protection against conducted noise from inductive loads. Mitsubishi specifies the module to IEC 61000-4-4 (electrical fast transient/burst) and IEC 61000-4-5 (surge immunity), which are the two most relevant EMC tests for relay output modules driving solenoid and contactor loads in industrial panels.

Contact Architecture: Each output is a Form A (normally open) contact with a common COM terminal shared across groups of four outputs (COM0 for Y0–Y3, COM1 for Y4–Y7). This grouping allows the two COM rails to be connected to different voltage sources — for example, COM0 to 24 V DC for solenoid valves and COM1 to 120 V AC for pilot lamps — without any external isolation relay. This is a practical hardware advantage in mixed-voltage panels that reduces wiring complexity.

Bus Interface Logic: The module’s expansion bus interface uses a parallel data latch architecture. Output states are written by the CPU during the output refresh phase of each scan and held in the latch until the next refresh. This means relay states are deterministic and do not depend on continuous bus activity — a relay that is commanded ON remains ON even if the expansion bus experiences a momentary communication glitch, because the latch retains the last valid state. The CPU monitors the expansion bus for communication errors and will set a diagnostic flag if the bus integrity is compromised.

Thermal Management: The relay coils and driver transistors are the primary heat sources within the module. At full load (all 8 outputs energized simultaneously at 2 A), the internal power dissipation remains within the module’s thermal design envelope up to the rated 55 °C ambient. The module does not require forced-air cooling in standard installations, but adequate panel ventilation is recommended when ambient temperatures exceed 45 °C.

System Integration Benefits

• Deterministic output refresh: Output states are updated synchronously with the CPU scan cycle. The relay switching command is executed within one scan period of the ladder logic instruction, giving the control engineer a predictable and measurable output latency — critical for sequencing applications where relay actuation order matters.
• Mixed-voltage load switching without external relays: The dual-COM architecture (COM0/COM1) allows two independent voltage rails on a single module, eliminating the need for interposing relays in mixed AC/DC panels and reducing component count by up to 8 relay sockets per module.
• Transparent diagnostic visibility: The FX0N CPU’s diagnostic buffer logs expansion bus errors, output short-circuit events (where load-side protection is fitted), and module communication timeouts. Faults are accessible via GX Works2 without interrupting production, enabling condition-based maintenance rather than time-based replacement.
• Zero-configuration address assignment: The FX0N expansion bus assigns output addresses (Y addresses) automatically based on module position in the expansion chain. No DIP switch setting or software address configuration is required. Swapping a failed FX0N-8EYR requires only mechanical replacement and rewiring — the address mapping is restored automatically on power-up.
• Low minimum switching load: The 5 mA at 5 V DC minimum load specification means the relay contacts can switch low-energy signals such as PLC input circuits or 24 V DC logic signals without contact welding or chatter — a capability not available on all relay output modules in this class.
• Broad load compatibility: The 240 V AC / 30 V DC, 2 A rating covers the majority of industrial discrete loads: 24 V DC solenoid valves (typically 0.5–1.5 A inrush), 120/240 V AC motor starter coils (typically 0.1–0.5 A sealed), and 24 V DC indicator lamps. No external current amplification is required for these standard loads.
• Compact expansion footprint: The FX0N-8EYR adds 8 output points in a housing that occupies approximately 90 mm of DIN rail. Compared to adding a second base unit or a larger CPU with more onboard I/O, the expansion module approach minimizes panel space consumption and avoids the cost of an additional CPU license or programming node.
• Long-term parts availability: The MELSEC FX0N platform has been in production for over two decades. Mitsubishi Electric maintains spare parts availability for legacy FX series hardware, and the FX0N-8EYR remains a stocked item in the global Mitsubishi distribution network, reducing the risk of obsolescence-driven line stoppages.

Quality Assurance & Global Logistics

Every FX0N-8EYR unit shipped from siemensplc.com is sourced through verified industrial supply channels with full traceability to authorized Mitsubishi Electric distributors. Units are inspected upon receipt for label authenticity (holographic Mitsubishi markings, correct date codes), housing integrity, and connector pin condition. Functional power-on verification is performed on units where test fixtures are available. All units are packed in anti-static bags with desiccant and humidity indicator cards, then boxed in double-wall corrugated cartons rated for international air freight handling.

Shipments originate from our Xiamen, China warehouse. Standard export documentation — commercial invoice, packing list, and certificate of origin — is prepared for every international order. For orders requiring FORM E (ASEAN), FORM F (China-Japan-Korea), or other preferential origin certificates, please advise at the time of order placement.

Logistics options from Xiamen:

• DHL Express: 2–4 business days to most destinations in Europe, North America, Southeast Asia, and the Middle East. Real-time tracking from pickup to delivery.
• FedEx International Priority: 2–5 business days. Preferred for shipments to the United States and Canada where FedEx ground network provides last-mile reliability.
• UPS Worldwide Express: Available on request for destinations with strong UPS coverage.
• Sea freight (LCL/FCL): Available for bulk orders exceeding 50 kg. Transit time 15–35 days depending on destination port.

In-stock units are dispatched within 1 business day of payment confirmation. A 12-month warranty from invoice date covers manufacturing defects and DOA (dead on arrival) units. Warranty claims are processed within 5 business days of receipt of the returned unit at our Xiamen facility.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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