Description
📌 FANUC A20B‑3900‑0181 — 16 MB FROM / 512 KB SRAM Memory Module
Description:
The FANUC A20B‑3900‑0181 is a combined memory module used in FANUC CNC controllers — especially in mid‑generation i‑Series systems such as Series 16i, 18i, and 21i. It contains both non‑volatile Flash ROM (FROM) and volatile SRAM that together store the CNC’s operating software and working data.
Key Features:
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💾 Flash ROM (FROM): 16 MB non‑volatile memory — holds the controller’s firmware, system code, and essential programs.
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🧠SRAM: 512 KB static RAM — used as working memory for runtime variables, machine parameters, and data buffering.
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⚙️ Function: Provides the core memory storage for the CNC’s control software and dynamic system data, enabling the controller to boot, run programs, and manage machine operations.
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🔌 Application: Typically found in FANUC Series 16i/18i/21i modular systems, where memory modules are separate boards that plug into the main control assembly.
Usage Notes:
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📂 After replacing this module, ALL FROM files, machine parameters, and programs must be reloaded from backups — because SRAM content is volatile and the FROM needs appropriate system code.
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🔄 This part is often stocked new, refurbished, or used by suppliers, with varying warranty and repair/return policies.
Typical Applications:
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Serving as the primary memory board in conventional FANUC i‑Series CNC controllers.
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Used where moderate memory capacity is sufficient for typical control programs and system code.