Mitsubishi MELSEC A-Series Modules BD625A988G52 A58B

Technical Dossier

Product Details And Specifications

Mitsubishi MELSEC A-Series Technical Notes

The Mitsubishi MELSEC A-Series programmable controller platform has maintained a dominant installed base across global heavy industry since its commercial introduction in the 1980s. Deployed extensively in petrochemical complexes, nuclear power auxiliary systems, steel rolling mills, and refinery distributed control architectures, the A-Series established the foundational I/O and CPU bus topology that Mitsubishi Electric carried forward into the Q-Series and iQ-R platforms. Its modular backplane design, deterministic scan cycle, and broad third-party compatibility made it the default PLC standard for large-scale process automation projects across Asia-Pacific, Europe, and the Middle East through the 1990s and into the 2000s. The BD625A988G52 A58B is a representative module within this ecosystem, used in programmable controller configurations requiring reliable digital I/O or CPU-level processing within the A-Series rack architecture.

The Evolution of MELSEC A-Series Architecture

The MELSEC A-Series was introduced as Mitsubishi Electric's first fully modular PLC family, built around a parallel backplane bus that allowed CPU, I/O, communication, and power supply modules to share a common rack. Early configurations used the A2 and A3 CPU modules with fixed-cycle scan execution. The architecture evolved through the A2A, A2N, A3N, and A2US generations, each adding expanded program memory, faster scan rates, and support for additional I/O points. The A1S sub-series introduced a compact slim-line form factor for space-constrained panel installations while maintaining full software compatibility with the standard A-Series instruction set (MELSAP-II ladder and SFC). Communication expansion followed with the introduction of MELSECNET/B and MELSECNET/10 network adapters, enabling peer-to-peer and hierarchical network topologies across large plant floors. By the mid-2000s, Mitsubishi Electric formally transitioned new project designs to the Q-Series, which offered 32-bit CPU architecture, high-speed bus, and IEC 61131-3 compliance. The A-Series entered end-of-life status progressively between 2008 and 2016, though installed units remain operational in facilities where full system replacement is not economically viable. Compatibility between A-Series and Q-Series is achievable via the A1S-to-Q conversion base units, but direct module interchangeability is not supported.

MELSEC A-Series Full Catalog & Functionalities (SKU List)

The following SKUs represent verified, commonly sourced modules within the Mitsubishi MELSEC A-Series platform. Modules are classified by functional category.

CPU Modules

A2USCPU-S1: Slim-line CPU, 14K steps, MELSECNET/10 compatible
A3NCPU: Standard CPU, 30K steps, multi-program execution support
A2NCPU: Standard CPU, 14K steps, base A-Series instruction set
A1SCPU: Compact CPU for A1S slim rack, 8K steps
A2ACPU: Enhanced CPU with extended data register capacity
BD625A988G52 A58B: Programmable controller module, A-Series rack-compatible, process control application

Digital Input (DI) Modules

AX40S: 16-point DC input, sink type, 24VDC
AX80: 32-point DC input, isolated commons, 24VDC
AX10: 8-point AC input module, 100–240VAC
AX41: 16-point DC input, source type, 24VDC

Digital Output (DO) Modules

AY40: 16-point transistor output, sink, 0.1A per point
AY80: 32-point transistor output, sink type
AY10: 8-point relay output, 2A per point, 240VAC/30VDC
AY41: 16-point transistor output, source type

Analog I/O Modules

A68AD: 8-channel analog input, 12-bit resolution, 4–20mA / 0–10V
A62DA: 2-channel analog output, 12-bit, voltage and current selectable

Communication & Network Modules

A1SJ71AP23Q: MELSECNET/10 optical loop master/local module
A1SJ71QBR11: CC-Link master/local module for A1S series
A1SJ71UC24-R4: RS-422/485 serial communication module

Power Supply Modules

A1S62P: 5VDC/3A power supply for A1S slim rack
A62P: 5VDC/6A power supply for standard A-Series rack