Description
📦 FANUC A20B-3900-0164 — Memory (FROM + SRAM Module)
The FANUC A20B-3900-0164 is a memory module printed circuit board used inside certain FANUC CNC controllers. It holds essential firmware and runtime data that the CNC control unit needs to operate.
Key Details
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📌 Type: Memory module, combining FROM (Flash Read-Only Memory) and SRAM (Static RAM) in one board.
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💾 FROM Capacity: 32 MB — stores the controller’s core software/firmware.
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⚡ SRAM Capacity: 2 MB — stores runtime data, parameters, and battery-backed information.
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🧠 Function: The FROM section contains the CNC control software; the SRAM section retains configuration data, machine parameters, and part programs while powered off (battery-backed memory).
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🔌 How It Works: Plugs into a designated memory slot on the CNC controller’s main board/backplane and is essential for the controller to boot and function correctly. Missing or faulty memory modules can prevent the machine from starting up or cause loss of important data.
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📍 Typical Compatibility: Used in FANUC i-Series (“B” models) controllers like 16i-B, 18i-B, 21i-B and sometimes in 30i/31i/32i systems that still use FROM/SRAM modules.
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🛠️ Status: Often discontinued by FANUC but widely available as new surplus or refurbished memory boards from aftermarket suppliers.