Mitsubishi FX-EEPROM-4 Replacement/Upgrade for MELSEC FX

Product Overview

Mitsubishi FX-EEPROM-4 Replacement/Upgrade for MELSEC FX: Seamless Transition from Legacy PLC Memory

When a Mitsubishi MELSEC FX-series PLC line reaches end-of-life or its memory cassette fails in the field, production downtime is measured in hours — not days. The FX-EEPROM-4 EEPROM Memory Cassette is the factory-specified program storage device for the MELSEC FX0, FX1, FX2, and FX2N controller families. TOPNLMS stocks verified FX-EEPROM-4 units ready for immediate dispatch from Xiamen, giving maintenance engineers and procurement teams a reliable, drop-in replacement path without redesigning the control architecture.

The FX-EEPROM-4 stores up to 4,000 steps of ladder logic in non-volatile EEPROM memory, eliminating the battery-backup dependency that plagues older RAM-based cassettes such as the FX-RAM-8 and FX-EPROM-8. When migrating from a battery-backed RAM cassette, the upgrade procedure is straightforward: transfer the existing GX Developer or GX Works2 program via the RS-422 programming port on the FX2N-48MR or FX2N-64MR base unit, verify the checksum, and seat the FX-EEPROM-4 into the cassette slot on the left side of the CPU module. No rewiring of the I/O terminal block is required, and the existing FX2N-8EX input expansion modules and FX2N-8EYR output expansion modules remain fully operational.

For sites running FX0 or FX1 controllers that are being consolidated onto a single FX2N platform, the FX-EEPROM-4 supports the same program file format used by GX Developer V8 and later, making cross-generation program migration practical. Engineers who have previously relied on the FX-EEPROM-8 for larger programs should note that the FX-EEPROM-4 is optimised for compact control tasks — conveyor sequencing, packaging line interlocks, and small-scale process control — where the 4K-step capacity is sufficient and the smaller physical footprint is advantageous in tight DIN-rail enclosures.

Compatibility Comparison Table

Seamless Upgrade Solutions

A successful FX-EEPROM-4 retrofit rarely involves the memory cassette alone. In practice, the migration touches several interconnected components. The SC-09 RS-422 programming cable is the standard interface between a Windows engineering workstation running GX Developer or GX Works2 and the FX2N CPU’s programming port; without a functional SC-09, program transfer to the new cassette is not possible. Sites that have upgraded to USB-based laptops without a native RS-422 port typically add a USB-SC09-FX USB-to-RS422 adapter to the bill of materials.

Where the FX2N base unit is mounted in a compact control cabinet alongside an FX2N-32MR or FX2N-48MT CPU, the cassette slot is accessible from the front face without removing the unit from the DIN rail, simplifying hot-swap procedures during scheduled maintenance windows. If the existing cabinet also houses an FX2N-4AD analog input module for temperature or pressure signal conditioning, no reconfiguration of the special function module parameters is needed after the memory cassette swap — the FROM/TO instructions in the ladder program read module data independently of the cassette type.

For sites transitioning from a standalone FX0 controller to a networked FX2N architecture, the addition of an FX2N-485-BD RS-485 communication board enables MODBUS RTU communication with downstream drives, HMI panels, and remote I/O stations. The FX-EEPROM-4 stores the updated communication ladder routines alongside the main sequence program, consolidating what were previously separate program files on the legacy FX-EPROM-8 into a single, field-writable cassette. Operators using a GOT1000 series HMI connected via RS-422 will find that screen navigation and data register mapping remain unchanged after the cassette replacement, provided the D-register assignments in the new program mirror the original.

Power supply integrity is a prerequisite for reliable EEPROM write operations. Before programming the FX-EEPROM-4 on-site, verify that the FX2N-1PS-5V internal power supply or the external 24 VDC rail supplying the CPU is within specification. Voltage fluctuations during a write cycle can corrupt the EEPROM contents, requiring a full re-transfer from the engineering workstation. A stable supply also protects the FX2N-8EX-ES/UL sink input expansion modules sharing the same 24 VDC bus.

Retrofit Guidance FAQ

Q: Can I replace the FX-RAM-8 with the FX-EEPROM-4 without modifying the ladder program?
A: Yes, provided the program is 4,000 steps or fewer. Transfer the existing program from the FX-RAM-8 to GX Developer first, then write it to the FX-EEPROM-4. No instruction changes are required.

Q: Does the FX-EEPROM-4 support the FX0N and FX1N series?
A: The FX-EEPROM-4 is primarily specified for FX0, FX1, FX2, and FX2N. Compatibility with FX0N and FX1N should be verified against the Mitsubishi hardware manual for those specific CPU variants before ordering.

Q: What programming software is required?
A: GX Developer V8.86 or later, or GX Works2. The SC-09 or USB-SC09-FX cable is required for the RS-422 programming port connection.

Q: Will the FX-EEPROM-4 retain the program during a power outage?
A: Yes. EEPROM is non-volatile and retains data indefinitely without battery backup, unlike the FX-RAM-8 which requires a functional FX-BATTERY to preserve program contents during power loss.

Q: Is the cassette slot physically identical across FX0, FX2, and FX2N CPUs?
A: The cassette connector and slot dimensions are standardised across the MELSEC FX compact series, allowing the same FX-EEPROM-4 unit to be installed in FX0, FX1, FX2, and FX2N base units without mechanical modification.

Q: Can the FX-EEPROM-4 be programmed off-line before installation?
A: Yes. Connect the cassette via the CPU programming port, write the program with GX Developer, then transport the cassette to the field and install it in the target CPU. This approach minimises on-site programming time and reduces the risk of errors during live commissioning.

Warranty Assurance

Every FX-EEPROM-4 unit shipped by TOPNLMS is covered by a 12-month warranty from the date of delivery. Prior to dispatch, each unit undergoes functional verification including EEPROM read/write cycle testing and connector integrity inspection. Units that fail to perform to specification within the warranty period are replaced at no additional cost, with return shipping coordinated by our after-sales team.

Orders are processed within one business day. Standard international shipping from Xiamen typically delivers within 5–10 business days depending on destination; expedited DHL and FedEx options are available at checkout for time-critical maintenance situations. Customs documentation, including commercial invoice and packing list, is prepared to facilitate smooth clearance for industrial components.

For procurement teams managing planned maintenance schedules, TOPNLMS can provide batch quotations and reserve stock against confirmed purchase orders. Contact our sales team at [email protected] or +86 18359293191 to discuss volume pricing, lead times, and technical pre-sales support.