Fanuc Dram Daughter Board Module A20B-2900-0140 A20B29000140 A2OB-29OO-O14O

FANUC A20B-2900-0140 | PMC-RE Memory Module — SCM / Series 16, 18, 160-MA CNC / A20B-2900 Series

Part Number: A20B-2900-0140

Manufacturer: FANUC Corporation (Japan)

Product Type: PMC-RE Memory Module — SCM (Sub Control Module)

PMC-RE and the SCM Module — Machine Ladder Logic in Dedicated Hardware

The A20B-2900-0140 is the SCM (Sub Control Module / Supplementary Control Module) memory module for FANUC's PMC-RE (Programmable Machine Controller — Relay Equivalent) used in Series 16, 18, and 160-MA CNC systems. The PMC-RE handles the machine-side ladder logic — the sequences and interlocks that control the ATC (Automatic Tool Changer), pallet system, hydraulics, coolant, doors, and all machine auxiliary functions that run alongside the CNC motion control.

The A20B-2900-0140 holds the PMC-RE control programme and associated data. In the FANUC CNC architecture, the PMC programme is stored on a dedicated memory module rather than in the main CPU's general memory — this separation keeps machine-specific ladder logic independent from the CNC's core system software, simplifying backup, restoration, and programme management.

When this module fails or is replaced, the PMC-RE ladder programme it contained is no longer present. The machine cannot execute any machine-side automation sequences until the PMC ladder is reloaded. All ATC operations, pallet changes, and machine auxiliary functions that depend on the PMC programme become unavailable.

Key Specifications

A20B-2900 Memory Module Series Context

The A20B-2900 series covers various memory and control modules for FANUC CNC systems. Each variant serves a defined function:

• A20B-2900-0140: PMC-RE control module (SCM) for Series 16/18/160-MA
• A20B-2900-0580: 14-bit A/D converter module
• A20B-2900-0482: 1.5 MB FROM module

Part numbers within the A20B-2900 series look similar but serve entirely different functions. Confirm A20B-2900-0140 from the installed module's label before ordering.

After Replacement — PMC Programme Reload Is Mandatory

This module stores the PMC-RE ladder programme. Replacing the A20B-2900-0140 without a current programme backup leaves the machine without its PMC control logic. Before removing the original module, back up the PMC programme through the CNC's programme I/O function or via the machine builder's backup procedure. After fitting the replacement, reload the PMC programme and verify all machine auxiliary sequences before returning to production.

FAQ

Q1: What is PMC-RE and how does it differ from the CNC's main programme memory?

PMC-RE (Programmable Machine Controller — Relay Equivalent) is FANUC's embedded PLC that runs the machine-side ladder logic independently from the CNC's motion control. It handles ATC sequences, hydraulic control, interlock logic, and all machine auxiliary automation. Its programme is stored separately — on the A20B-2900-0140 module — so the machine ladder can be backed up, modified, and restored without affecting the CNC system software.

Q2: Can the A20B-2900-0140 be replaced while the PMC programme data is preserved?

Only if a complete current backup of the PMC ladder programme exists. The module itself stores the programme — when removed, the programme is no longer available in the system. Replacing the module with the programme backed up elsewhere allows a clean reload after installation. Without a backup, the PMC programme must be rebuilt from the machine builder's documentation.

Q3: What symptoms indicate the A20B-2900-0140 has failed?

Failures of the PMC-RE module typically produce alarms at CNC startup related to PMC communication or initialisation errors. Machine auxiliary functions — ATC, pallet, doors, coolant — that depend on PMC outputs do not operate. The CNC axis motion may still function if the PMC fault only affects auxiliary functions, but machine safety interlocks through the PMC may prevent axis operation as well.

Q4: Is the A20B-2900-0140 compatible with all Series 16 and 18 variants?

The module is confirmed for FANUC Series 16, 18, and 160-MA CNC controls using the PMC-RE function. Not all Series 16/18 controls use PMC-RE — some use PMC-R or PMC-N variants with different memory module requirements. Confirm the specific PMC type installed in the CNC from the machine's FANUC hardware documentation before specifying the A20B-2900-0140.

Q5: Where is the A20B-2900-0140 sourced?

Through the FANUC Series 16/18 CNC aftermarket — FANUC spare parts specialists, industrial CNC repair centres, and tested surplus dealers. Confirm A20B-2900-0140 specifically from the installed module's label. Adjacent A20B-2900 variants serve different CNC functions and are not interchangeable.