Description
The FANUC A20B-3900-0183 is a memory card/module used inside industrial FANUC CNC controller systems. It combines Flash ROM (FROM) and Static RAM (SRAM) on a single board — providing both permanent storage for firmware and a reservoir for runtime data and machine parameters.
📌 What It Is
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Part Number: A20B-3900-0183
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Type: FROM + SRAM memory module (printed circuit board)
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Memory Configuration:
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32 MB Flash ROM (FROM) — stores essential firmware and system programs
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512 KB SRAM — battery-backed memory for parameters and runtime variables
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🧠 Function in a FANUC CNC Controller
This module sits inside the controller electronics alongside CPU cards, servo/axis modules, and other memory boards. Its roles include:
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💾 Firmware Storage: Holding the CNC’s operating software and control routines that the system loads at startup.
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⚡ Parameter Memory: Storing machine settings, configuration parameters, and other runtime information that must be retained even when the controller is powered off — supported by a backup battery on the SRAM portion.
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⚠️ Controller Boot & Operation: Without a functioning memory module like this, a FANUC CNC controller may fail to boot or throw memory/parameter errors.
📋 Typical Compatibility
Memory modules from the A20B-3900 series are used in a variety of FANUC controller families that employ modular memory cards, including older “B” and Series 20 CNC controls such as:
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FANUC 16i-B
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FANUC 18i-B
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FANUC 21i-B