• JANCD-MM21-2: 150 KB memory

• JANCD-MM21-6: 2560 KB (2.5 MB) memory

  Function: stores CNC programs, parameters, tool offsets, and robot job data.

  Status: Discontinued (EOL); only used/refurbished available.

2. Basic Information

• Model: JANCD-MM21

• Variants: MM21-2 (150KB), MM21-6 (2.5MB)

• Manufacturer: Yaskawa Electric (Japan)

• Type: Volatile CMOS RAM with NEC 5.5V battery backup

• Compatible systems: YASNAC X3, MX3 CNC & robot controllers

• Battery: NEC 5.5V (data retention when power off)

• Weight: ~1.5 kg

• Form factor: Standard 3U industrial board

3. Technical Specifications

• Memory:

  • MM21-2: 150 KB CMOS RAM

  • MM21-6: 2560 KB (2.5 MB) CMOS RAM

• Backup: NEC 5.5V lithium battery (≈5–10 years life)

• Interface: Proprietary parallel bus (X3/MX3 backplane)

• Power: 5 VDC (backplane supplied)

• Operating temperature: 0 °C to +50 °C

• Storage temperature: −20 °C to +70 °C

• Humidity: 5%–80% RH (non-condensing)

4. Key Functions

• Stores CNC user programs, motion parameters, tool offsets, I/O data, robot jobs.

• Battery-backed: retains data during power loss (critical for legacy systems).

• Works with system ROM/flash boards for firmware.

• Supports online editing, program execution, and high-speed data buffering.

5. Compatibility

• Fits: YASNAC X3, MX3 CNC & robot controllers

• Not compatible with MM14/MM15/MM20 series, PK1, ERC/XRC, or non-Yaskawa systems.

6. Installation & Safety

• Power off controller fully before insertion/removal (no hot swap).

• Use grounded ESD wristband to prevent static damage.

• Align edge connector, seat firmly, and tighten screws.

• Replace battery every 5–10 years to avoid data loss.

• Keep dry, dust-free; avoid oil, shock, or impact.

7. MM21 vs MM20 (Quick Compare)

• MM20: 256 KB, no battery (volatile), for PK1/ERC/XRC.

• MM21: 150 KB / 2.5 MB, battery-backed, for X3/MX3.