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Verify current license configuration

Access MOD > Set-up > Control Info and document the licensed number of axes and encoder interfaces. Compare this with the alarm's permitted value (%2).

The license information shows 'NCK axes' and 'Encoder inputs' separately - both contribute to HSCI device count.

Count physical HSCI devices

In MOD > System Configuration > Device Configuration, review all detected encoders including linear scales, rotary encoders, angle encoders, and touch probe interfaces. Count all EnDat and 1 Vpp devices.

On TNC 640, check both CC (Component Controller) and UMC (Universal Motion Controller) modules for connected devices.

Identify excess devices

Determine which encoders or devices exceed the licensed count. Check if any are unused, redundant, or connected for testing purposes that can be removed.

Do not disconnect encoders on live axes without proper machine shutdown and safety lockout procedures.

Request license upgrade

If all connected devices are required, contact Heidenhain service with your control ID number (from Control Info screen) to purchase additional axis or encoder licenses. Provide current configuration details.

License upgrades are typically delivered as FCL files loaded via TNCopt or SD card - they do not require hardware changes.

Access system configuration files

Enter MOD mode (password may be required), navigate to PLC > Edit > System Files, and open CNC.SYS (TNC 640) or TNC.SYS (iTNC 530/TNC 320). Search for encoder assignments in the [ENCODER] or [CHANNEL] sections.

Create a backup of system files before editing - save to USB/network location. Incorrect modifications can prevent control startup.

Check for duplicate device IDs

Review each encoder definition looking for duplicate 'EnDat address', 'HSCI channel', or encoder input assignments. Each physical encoder must have only one unique configuration entry.

Use the 'Find' function (search for 'ENCODER' or 'ENDAT') to locate all encoder references throughout the file.

Remove duplicate entries

Delete any redundant encoder definitions. Ensure each axis has exactly one encoder assignment and no orphaned encoder configurations exist from previous machine modifications.

Comment out suspicious entries with semicolon (;) instead of deleting - allows easy rollback if needed.

Reboot and verify

Save the modified system file, perform a complete control reboot (power cycle), and check MOD > System Configuration > Device Configuration to confirm device count now matches permitted value.

Check the boot log (if accessible) for HSCI initialization messages to confirm proper device enumeration.

Identify control model and limits

From the startup screen or MOD > Set-up > Control Info, confirm exact control model (TNC 320, iTNC 530, TNC 640, etc.) and note NC software version. Reference Heidenhain documentation for model-specific HSCI device limits.

TNC 320 typically supports up to 4 axes, iTNC 530 up to 9 axes, TNC 640 up to 18 axes - but encoder counts may differ from axis counts.

Document machine requirements

List all required encoders: linear scales for each axis, spindle encoder, handwheel interfaces, angle encoders, and touch probe systems. Calculate total HSCI device requirement.

Don't forget auxiliary encoders - some machines use separate encoders for backlash compensation or gantry synchronization.

Evaluate upgrade options

If requirements exceed control capability, evaluate: (1) upgrading to higher-capacity control model, (2) license expansion if hardware supports it, or (3) redesigning machine configuration to reduce encoder count.

Control model upgrades may require PLC program modification, machine parameter reconfiguration, and electrical cabinet changes.