The zeroing operation of the equipment is enhanced by Z-pulse zeroing, which further improves the accuracy of the zero point. Further details will be described step-by-step.
Controller Hardware:
- TwinCAT Controller, PC or EPC, including:
- Embedded Controller: CX5140-0125
- Industrial PC: C6xxx, CP2xxx, CP6xxx, etc.
Control Software:
- TwinCAT 3.1 Build 4024.22
- TwinCAT 3 PLC Program
Zeroing Sequence
For default zeroing, the reference zero position is determined by the position latched by the zero switch or Z signal, which serves as the reference for the entire system. The zeroing process is divided into three steps:
- Move to the reference zero switch.
- Move away from the reference zero switch.
- Move back to the zero switch to establish the reference point.
Each of these steps can be executed at specified speeds.
Special Zeroing Methods:
In certain scenarios where the default zeroing method does not suffice, the following special methods based on different parameters are utilized:
- Zeroing away from the reference point.
- Zeroing without reverse movement.
- Zeroing using only the Z-pulse method.
- Zeroing by reversing the zeroing direction and signal polarity to determine the valid direction of operation.
Z-Pulse Zeroing Steps
Z-pulse zeroing requires hardware support. The system captures the Z-pulse position through probe functionality, unlike switch zeroing where the accuracy depends on the speed of moving away from the switch. Z-pulse zeroing is not influenced by this speed.
The default zeroing method does not detect the Z-pulse signal; after detecting the zero switch signal, it then proceeds to locate the Z-pulse signal. Reference the following three operational phases:
Phase1
- Phase 1 - Move towards the zero switch:
- Parameters:
- P-AXIS-00158 (ref_richt) - Direction to reference point
- P-AXIS-00219 (vb_refmax) - High speed setting for reference movement
After switching to zeroing mode with command G74, Phase 1 starts. Ensure the axis is positioned before the zero switch to avoid not finding it. Once the switch is hit, the CNC notifies the HLI interface to stop the axis, then moves to Phase 2.
Phase2
- Phase 2 - Move away from the zero switch:
- Parameters:
- P-AXIS-00064 (fast_from_cam) - Fast or slow speed away from the zero switch
- P-AXIS-00158 (ref_richt) - Direction to reference point
- P-AXIS-00219 (vb_refmax) - High speed setting for reference movement
- P-AXIS-00218 (vb_reflow) - Low speed setting for reference movement
If Phase 1 completes successfully, Phase 2 automatically begins with the axis moving away from the zero switch at the set speed. The CNC notifies the HLI interface to stop once the movement is complete, then proceeds to Phase 3.
Phase3
- Phase 3 - Move towards the zero switch to find the Z signal:
- Parameters:
- P-AXIS-00084 (homing_without_zero_pulse) - Whether to use Z-pulse for zeroing
- P-AXIS-00158 (ref_richt) - Direction to reference point
- P-AXIS-00218 (vb_reflow) - Low speed setting for reference movement
If Phase 2 completes successfully, Phase 3 automatically finds the zero position corresponding to the Z-pulse.
- Phase 3 - Move towards the zero switch to find the Z signal:
- Parameters:
- P-AXIS-00084 (homing_without_zero_pulse) - Whether to use Z-pulse for zeroing
- P-AXIS-00158 (ref_richt) - Direction to reference point
- P-AXIS-00218 (vb_reflow) - Low speed setting for reference movement
If Phase 2 completes successfully, Phase 3 automatically finds the zero position corresponding to the Z-pulse. - See Figure for reference：
Hardware Configuration Example
- Parameters:
- P-AXIS-00084 (homing_without_zero_pulse) - Whether to use Z-pulse for zeroing
- P-AXIS-00156 (ref_ohne_nocken) - Zeroing without finding zero switch
- P-AXIS-00157 (ref_ohne_rev) - Zeroing without reverse movement
- Example settings for Z-pulse zeroing:
- P-AXIS-00084 set to 0, P-AXIS-00156 set to 0: The system first finds the zero switch, then the Z-pulse.
- P-AXIS-00084 set to 0, P-AXIS-00156 set to 1: Only finds the Z-pulse if there's only one Z signal in the full travel.
- P-AXIS-00157 set to 1: No reverse movement upon hitting the zero switch; set to 0 for reverse movement.
CNC Axis Parameters - Input/Output Associations:
- Input:
- 60B9_00 touch probe status
- 60BA_00 touch probe pos1 pos value
- Output:
- 60B8_00 touch probe function
Upon executing G74 for zeroing with P-AXIS-00084 set to 0 for Z-pulse zeroing, 60B8 outputs a probe enable signal (21). If a Z-pulse is detected, the position is captured in 60BA, and 60B9 shows status 1, completing the zeroing while ensuring positional uniqueness. Z-pulse zeroing provides higher accuracy compared to switch zeroing. See Figure for reference.
