MELSEC-A is Mitsubishi Electric's legacy mid- and large-scale PLC platform — large A/QnA rack systems and compact AnS/QnAS — shipped since the mid-1980s. Production and mainline repair have ended. This page is a guide for plants that still run MELSEC-A systems: key lifecycle dates, the remaining maintenance battery, and migration to MELSEC iQ-R with TKK support. It is not a catalog of orderable A-series controllers.

MELSEC-A Series lifecycle: key dates

• Large A/QnA: production ended September 2006; repair ended September 2013.
• AnS/QnAS: production ended September 2014; repair ended September 2021.
• Last platform power supplies A61PN and A61RP: production ended 31 December 2025 (order acceptance closed 28 November 2025).
• No orderable MELSEC-A / AnS / AnU CPU, I/O, base, or network modules remain.

These are Mitsubishi Electric's global dates from FA notices and renewal pages. Residual accessory availability in Thailand is not confirmed on this page — contact TKK before planning a purchase.

Migrating to MELSEC iQ-R

Mitsubishi Electric recommends replacing MELSEC-A installed systems with MELSEC iQ-R. Use the official transition handbooks for capacity and module mapping. Replacements are not drop-in: wiring, programs, and specifications generally need review.

• Large A/QnA systems: transition handbook L08666ENG (examples: A2ACPU to R01CPU; A3ACPUP21 to R04CPU).
• AnS/QnAS systems, including A2USHCPU-S1: transition handbook L08668ENG (example: A2USHCPU-S1 to R04CPU).
• Select the iQ-R CPU by capacity and function needs; handbook examples are not automatic one-to-one swaps.

Need an installed-base survey or a migration plan to MELSEC iQ-R? Contact TKK.

Models in the series

Orderable MELSEC-A PLC CPUs, I/O modules, bases, and network modules: none. The only KEEP accessory listed for web reference is the maintenance battery below. Confirm stock with TKK

• Maintenance battery (confirm stock): A6BAT — lithium thionyl-chloride, DC 3.6 V, for IC-RAM backup and power-loss retention on A/QnA systems.

Historical CPU examples for identification only (not orderable): A2USHCPU-S1 (production ended September 2014), A3ACPUP21 (September 2008), and A2ACPU (September 2006). Use these names when matching plant drawings for migration planning.

Programming software

ACPU projects were historically programmed with GX Developer. GX Works2 and GX Works3 do not support ACPU modules. GX Developer commercial packages were discontinued in September 2023 and are not listed here as current orderable SKUs. When moving to iQ-R, plan for program conversion and ask TKK for tool and survey advice.

Which page covers the documented MELSEC-A migration target?

• MELSEC iQ-R Series

Why choose TKK for Mitsubishi Electric products?

TKK helps factory teams source, select and support Mitsubishi Electric products with confidence, from the first quotation to long after installation.

• Official Mitsubishi Electric distributor, supplying genuine products through an authorized channel.
• Competitive, value-focused pricing for single units and project quantities.
• Ask us about current availability, and our specialists can recommend a suitable replacement if needed.
• A team of product specialists ready to advise on model selection, application and replacement.
• Dedicated, responsive after-sales service and technical support.

Running MELSEC-A, AnS, or AnU controllers? Contact TKK about residual spares (including A6BAT stock confirmation) and a migration plan to MELSEC iQ-R.