This service manual provides comprehensive information for the diagnosis and correction of errors on TNC-controlled machine tools, specifically referring to the TNC 426/TNC 430 with NC software versions 280.474/475 and 280.476/477, as well as the TNC 426 CB/PB / TNC430 CA/PA for NC software 280 470/471/472/473. It also references other service manuals for TNC 426 CA/PA and Inverter Systems and Motors. The manual is regularly updated, with the current printable version available on the HEIDENHAIN website. Printed copies are primarily distributed to participants of service training courses.
Function Description:
The TNC (HEIDENHAIN TNC 426/430) is an NC control system designed for machine tools, featuring an integral monitoring system to prevent input or operation errors and to identify and diagnose technical errors within the TNC and connected units. This monitoring system is a core component of both the TNC hardware and software, active whenever the control is switched on. It communicates technical faults or operational errors through clear, plain-language messages.
During operation, the TNC continuously monitors various critical parameters to ensure optimal performance and safety. These include:
- Encoder Signals: Amplitude and edge separation of encoder signals are monitored to ensure accurate position feedback.
- Absolute Positions: For encoders equipped with distance-coded reference marks, the absolute positions are tracked.
- Position Monitoring: Current position (servo lag monitoring) and actual path traversed (movement monitoring) are continuously checked. Position deviation at standstill is also monitored to ensure stability.
- Speed Control: The nominal speed value is monitored for deviations.
- Memory Integrity: CRC sums of EPROM, RAM, and Flash memory are verified to detect data corruption.
- Power Supply: The overall power supply and buffer battery voltage are monitored.
- Environmental Conditions: The operating temperature of the logic unit is tracked.
- PLC Program: The run time of the PLC program is monitored for irregularities.
For digital axes, the TNC extends its monitoring capabilities to include:
- Motor Performance: Motor current, motor temperature, and the temperature of the power module are observed.
- Voltage Levels: DC-link voltage and the supply voltage of the power module are monitored.
- Thermal Load: The I²t (current squared time) of the power module and motor is monitored to prevent overheating.
The TNC also includes interfaces for PLC inputs and outputs, machine operating panels, and PL connections, all designed to comply with basic insulation regulations (IEC 742 EN 50 178). This ensures safety and proper integration with other devices.
Usage Features:
The TNC's integral monitoring system provides different reactions to error messages based on their severity and priority. These reactions range from simple display messages to critical system shutdowns.
- Display Only: For minor issues, an error message is displayed, which can be reset with the CE key. TNC operation remains possible, and additional information is available via the HELP key.
- NC Stop: For more significant errors, the TNC performs an NC stop, braking the axes at the nominal value characteristic. The error can be reset with the CE key, and TNC operation is still possible, with HELP key information available.
- EMERGENCY STOP: In critical situations (e.g., emergency-stop button activation or hardware limit switch), axes decelerate at the current limit. The error can be reset with the CE key, TNC operation is possible, and HELP key information is provided.
- "Control is ready" Reset: For certain errors, the "Control is ready" output is reset, causing axes to decelerate at the current limit. Some errors may require a reference-mark traverse for the affected axis. TNC operation is still possible, and HELP key information is available.
- Blinking Error Message (Red Window) with Reset: More severe errors result in a blinking red error message, disabling the TNC keyboard and decelerating axes at the current limit. The error can be reset with the END BLOCK key or the main On/Off switch, but all axes must be re-referenced afterward.
- Operating-System Error Message (White Letters on Black Background) with Reset: The most critical errors, such as "HEIDENHAIN FATAL ERROR," cause axes to decelerate at the current limit, disable the TNC keyboard, and require resetting the error with the END BLOCK key or main On/Off switch. All axes must be re-referenced.
The manual also details various error messages, their causes, and corrective actions, covering issues from incorrect programming and parameter settings to hardware malfunctions. This structured approach helps users quickly identify and resolve problems.
Maintenance Features:
The service manual emphasizes the importance of proper maintenance and troubleshooting procedures.
- Hardware Identification: The manual provides guidance on identifying HEIDENHAIN components and displaying system information, which is crucial for maintenance and part replacement.
- Connector Designation and Layout: Detailed information on connector designations, positions, and pin layouts for logic units, PLC expansion boards, TNC operating panels, visual display units, interface cards, machine operating panels, and handwheels is provided. This is essential for correct wiring and troubleshooting.
- Power Supply Diagnostics: The manual includes sections on checking various power supply units (LE 426 CB/430 CA, LE 426 PB / 430 PA, LE 426M / 430M with Simodrive 611D or HEIDENHAIN Inverter), power supply to PLC components, and buffer battery status.
- Keyboard Unit Checks: Procedures for checking the keyboard unit (TE 401 B/420) and its key matrix are outlined.
- Visual Display Unit Checks: Instructions for checking BC 110 B, BC 120, and BC 120F visual display units are included.
- File Management: The manual covers file management within the TNC, including code numbers, data storage locations, TNC and PLC partitions, machine parameter editor, switching position display for service, and command shell usage.
- Encoder Interface: Detailed information on position and speed encoder circuits, and inspecting position encoders, is provided for accurate motion control.
- Enables Checking: Procedures for checking the "Control-is-Ready" output and acknowledgement signals, along with flowcharts of the TNC booting routine, are included to ensure the control system is properly initialized.
- Interface to Servo Amplifier: This section details analog/digital nominal value settings, an overview of test routines for error diagnosis (including 11 specific routines), speed adjustment at the servo amplifier, adjusting electrical offset, and using the integrated oscilloscope.
- PLC Interface: Specifications, monitoring PLC inputs and outputs, service diagnosis in PLC mode (TRACE function, LOGIC diagram, TABLE function), recompiling PLC programs, calling PLC error tables, creating cross-reference lists, and nonvolatile PLC markers and words are covered.
- Serial Handwheels and Touch Probes: Information on various serial handwheels (HR 130/130.001/330, HR 332, HR 410) and 3-D touch probes (TS 220, TT 130, TS 630/TS 632) is provided, including overviews of their functions for workpiece setup, measurement, and digitizing.
- Data Interfaces: Wiring diagrams and operating modes for RS-232-C/V.24 and RS-422/V.11 data interfaces are detailed, along with instructions for file transfer (downloading and uploading).
- Replacing Instructions: Critical information on NC software updates for different PGM numbers (280 474/475, 280 476/477), EPROM and Flash hardware, backup/restoring hard-disk data, and exchanging the complete logic unit is provided.
- Inspection, Measuring, and Test Equipment: The manual lists and describes specialized test equipment such as the Universal Test Adapter, Encoder Diagnostic Set PWM 8, and Drive Control Generator DCG, including their functional descriptions and accessories.
- Machine Parameter List: A comprehensive list of machine parameters is included, which is essential for configuring and fine-tuning the TNC.
Service personnel are cautioned to possess comprehensive knowledge of drives, inverters, NC controls, and measuring systems. Improper operation, incorrect programming, or non-optimized machine parameter values can lead to faulty machine performance. HEIDENHAIN disclaims responsibility for damage or injury resulting from improper use. It is also emphasized that machine parameters should only be altered by the machine manufacturer or after consultation with them.
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