Migrating Mitsubishi FX2N and FX1N to iQ-F FX5
Mitsubishi FX controllers run a large share of the UK’s smaller machines, and many of them are still FX2N and FX1N units from the 2000s. Both families are long finished. Mitsubishi Electric Europe lists the FX2N main units as discontinued in September 2012, FX2N expansion units in December 2015 and the whole FX1N series in December 2015, and says that service or support for these legacy series is no longer possible. The FX2N special function blocks have followed: Mitsubishi’s European table gives an end of service of December 2022 for the FX2N-4AD, 4DA and 1PG-E, for example.
The FX3 family is now on the same path. In Europe, Mitsubishi’s notice gives FX3U, FX3UC and FX3S a last order date of 31 January 2027 and repairs until June 2033; the FX3G last order date has already passed. So an FX3 is no longer a sensible place to move an FX2N to. The target is MELSEC iQ-F (FX5).
Choosing the FX5
| Model | Fits | Main limits |
|---|---|---|
| FX5S | Small machines | 48k steps, no extension modules, no SFC, no battery |
| FX5UJ | Small to medium machines | 48k steps, up to 8 extension modules, 256 I/O |
| FX5U | General purpose | 128k steps, 512 I/O, built-in analog, RS-485 |
| FX5UC | Compact, connector-type I/O | 128k steps, 512 I/O, RS-485 |
All FX5 CPUs have Ethernet built in. Mitsubishi’s guidance is to check program size, I/O count, extension modules, serial channels and analog adapters: above 48k steps, 256 I/O, eight extensions, two serial channels or two analog adapters, you need an FX5U or FX5UC. Also check whether the program uses SFC (not supported on FX5S) or STL and whether it depends on retained data, because file registers are not latched on the FX5S or FX5UJ.
The expansion blocks have to go
This is where FX2N migrations surprise people. Mitsubishi’s FAQ is unambiguous: FX2N I/O and extension modules, and FX2 intelligent function modules, cannot be connected to any FX5. Only FX3 intelligent function modules connect, and only on FX5U or FX5UC through the FX5-CNV-BUS or FX5-CNV-BUSC bus adapter (one per CPU). You may see claims online that some FX2N blocks work through the adapter; Mitsubishi does not support it, and we would not build a production machine on it.
Budget to replace every FX2N block. Mitsubishi’s replacement tables give the main equivalents:
| FX2N block | FX5 replacement |
|---|---|
| FX2N-2AD, 2DA, 5A | FX5-4A-ADP, FX5-4AD/4DA(-ADP), or FX5U built-in analog |
| FX2N-8AD | FX5-8AD |
| FX2N-4AD-PT, 4AD-TC | FX3U-4AD-PT/TC-ADP in Mitsubishi’s table; FX5-4AD-PT-ADP and FX5-4AD-TC-ADP are the FX5 equivalents |
| FX2N-10PG | FX5-20PG-D |
| FX2N-10GM | FX5 built-in positioning |
| FX2N-20GM | FX5 CPU with FX5-20PG-P and the FB library |
| FX2N-32CCL | FX5-CCL-MS |
| FX2N-232IF | FX5-232ADP |
| FX2N-16EX, 32ER and other extension I/O | FX5 extension I/O (for example FX5-16EX/ES, FX5-32ER/ES) |
Some fieldbus modules have no FX5 successor in Mitsubishi’s notices, including FX2N-64DNET (DeviceNet) and FX2N-32DP-IF-D. Those machines need a different network plan.
Analog scaling changes too. Even between the FX3U-4AD and the FX5-4AD, Mitsubishi notes different ranges, resolutions and terminals and says the program has to change; expect at least as much from an FX2N block.
Converting the program
GX Works3 converts FX3 projects saved in GX Works2 format (Project > Open Other Format File > GX Works2 Format). Mitsubishi’s transition handbook covers FX3G, FX3U and FX3UC as the source; we have found no official Mitsubishi handbook for converting FX2N or FX1N programs directly. The route engineers use is:
- Open the GX Developer project in GX Works2 and save it in GX Works2 format.
- Change the PLC type to FX3U and fix what that throws up.
- Open it in GX Works3 and convert to the chosen FX5.
Expect rework at every step. Practitioners report that projects saved as GX Works2 “Simple” projects convert, while “Structured” projects have lost content, and that parameter errors are normal. Mitsubishi itself warns that conversion “may not be performed according to the state of the project”.
What to look for after conversion:
- Unsupported instructions become placeholders. They are converted to OUT SM4095 (or SM4095/SD4095), and out-of-range interrupt pointers become P4095. Search for them; each one is logic that needs rewriting. PLSR and ZRN are common examples, and PLSY, PLSV, DSZR and DHSCR need their parameters adjusting.
- Parameters are deleted. Apart from CC-Link network parameters, everything is set again by hand in the FX5 system parameters.
- Timers and renamed instructions. Timer coils change by resolution (OUTHS, OUTH, OUT), and instructions such as INT, SQR and SER have new names.
- High-speed counters. Mitsubishi’s handbook notes that C235 to C255 do not work just by changing the CPU type, and that the counter parameters and program have to change. Check this for the specific FX5 model.
- Special relays and registers. FX5 provides an FX-compatible range from SM8000 and SD8000, but do not assume every M8xxx or D8xxx has an equivalent. Check each against Mitsubishi’s device replacement list.
- Serial channel numbers change, and so do the instructions and parameters that reference them.
- Program size can grow, so check it still fits the target CPU.
Hardware and HMIs
- Footprints and terminals differ. FX5 units have different widths, mounting-hole pitches and terminal blocks from the FX they replace, and analog modules move from screw terminals to spring clamps. Plan panel modifications and rewiring rather than a drop-in swap.
- Inputs. The FX5U has no 0 ms input filter setting for high-speed, interrupt and pulse-catch inputs, so noisy inputs that were fine on an FX may need attention.
- Positioning moves to FX5 built-in positioning or FX5 positioning modules, and needs recommissioning.
- HMIs. GOT2000 terminals connect to FX5 over Ethernet; older Mitsubishi display modules (FX-10DM, FX3U-7DM) are discontinued, with the FX5’s built-in web server or a GOT as the replacement.
Before you start
- Upload and archive every program, with comments, and check it matches what is running.
- List every block and adapter against Mitsubishi’s end-of-life tables. FX2N extension and special blocks are the biggest cost driver.
- Choose the FX5 using the size, I/O and extension limits above.
- Convert through GX Works2 to GX Works3, then work through the placeholders, parameters, counters, positioning, analog scaling and serial channels.
- Plan the panel work and GOT screen updates.
- Bench test, then test on the machine, including timing, before handing it back.
How ECS approaches it
FX migrations are usually machine by machine, across machines from different builders, and the program on site is often the only copy. A Capture audit backs up every reachable FX program and records every block and adapter, so the cost of each migration is known before anyone commits to it. The converted programs, versions and cables are then held in Command Centre.
We carry out FX conversions, panel modifications and recommissioning in-house as part of our automation projects, usually around planned stops.
Sources
- Mitsubishi Electric Europe, Product Life Cycle Information, EOL MELSEC FX2N Series, EOL MELSEC FX3 Series and FX2N extension block bulletin
- Mitsubishi Electric, Transition from MELSEC FX3G, FX3U, FX3UC Series to MELSEC iQ-F Series Handbook (JY997D66201)
- Mitsubishi Electric, Transition handbook for intelligent function modules (L0810002ENG)
- Mitsubishi Electric FAQ, connecting older modules to FX5 and converting FX3 projects in GX Works3
- Mitsubishi Electric, FX2N-10GM/20GM end of production
Lifecycle dates differ by region and by model. Check a specific model with Mitsubishi Electric UK or your distributor before buying or planning around it.