1012

Check Battery Status in Diagnostics

Navigate to Diagnostics → Hardware → NCU → Power Supply and check the backup battery voltage reading. Normal voltage should be above 3.0V.

Document the voltage reading and date for maintenance records

Access NCU Battery Compartment

Power down the system safely, open the NCU housing, and locate the backup battery (usually a 3.6V lithium cell with connector).

Ensure main power is connected during battery replacement to prevent data loss

Replace Battery with Siemens Part

Replace with genuine Siemens battery (part number varies by NCU model). Connect new battery and verify voltage reading returns to normal range.

Keep machine powered during replacement - you have approximately 10 minutes of capacitor backup

Clear Alarm and Test

Power cycle the system, clear alarm 1012 using the alarm acknowledgment, and verify battery voltage remains stable in diagnostics.

Update maintenance log with battery replacement date for future reference

Identify Memory Module Type

Check Diagnostics → Hardware → Memory to identify if PCMCIA cards or CompactFlash modules are installed and their battery status.

Some older SINUMERIK systems use PCMCIA SRAM cards with individual batteries

Backup Critical Data

Immediately backup all programs, tool data, and parameters via RS232 or network before removing memory modules.

Do not remove memory modules without backing up data first

Replace Memory Module Battery

Remove memory module, replace internal battery (if serviceable), or replace entire module with new Siemens-compatible unit.

Consider upgrading to newer flash-based memory modules that don't require backup batteries

Measure Supply Voltages

Use multimeter to verify 24VDC supply stability at NCU terminals. Check for voltage drops under load or excessive ripple.

Voltage should remain within ±5% of nominal 24VDC

Check Battery Charging Circuit

In Diagnostics → Hardware → Power Supply, verify the battery charging status and charging current readings.

Faulty charging circuits can overcharge and damage batteries

Inspect Power Connections

Check all power supply connections to NCU for corrosion, loose terminals, or damaged wiring that could cause voltage instability.

Clean and retighten all power connections using proper torque specifications

Monitor Cabinet Temperature

Check ambient temperature in electrical cabinet and verify it's within specified range (typically 0-55°C for NCU operation).

Install cabinet cooling or heating if temperature extremes are common

Check Temperature Compensation

Verify machine parameter MD11210 (temperature compensation) is properly configured for your installation environment.

Some SINUMERIK systems have temperature-dependent battery monitoring thresholds

Improve Cabinet Climate Control

Install adequate ventilation, heating, or cooling to maintain stable temperature around the NCU and prevent temperature-induced alarms.

Condensation from temperature cycling can damage electronic components

Verify Battery Voltage Externally

Measure actual battery voltage with external multimeter and compare to voltage reported in SINUMERIK diagnostics.

Significant discrepancy indicates NCU monitoring circuit failure

Check NCU Firmware Version

Verify NCU firmware is current version via Startup → Version. Some older firmware versions had battery monitoring bugs.

Firmware updates require proper backup and may need Siemens authorization

Contact Siemens Support

If battery voltage is good but alarm persists, contact Siemens technical support for NCU hardware evaluation and possible replacement.

Document all voltage measurements and firmware versions for support call