Load Cell Probe Troubleshooting

This article is used to record Klipper load_cell / load_cell_probe related keywords and basic troubleshooting directions. Load Cell probes are still a relatively new solution; ordinary users should not modify their printers with pressure sensors based on scattered community configurations. Please prioritize using product documentation, official Klipper documentation, or complete configurations provided by the manufacturer.

Common Keywords

Keyword	Common Meaning	Troubleshooting Direction
[load_cell_probe]	Using a pressure sensor as a probe	Verify if the current Klipper version supports this configuration section
LOAD_CELL_DIAGNOSTIC	Load Cell diagnostic command	Used to view sample rate, saturated samples, and valid data changes
Invalid ads1220 reset state	ADS1220 initialization state异常	Check chip configuration, SPI/I2C connections, and firmware support
No trigger on probe after full movement	Probe did not trigger within the allowed travel range	Check probe threshold, Z-axis direction, travel range, and sensor readings
Saturated samples	Sensor sampling saturation	Possible overload, inappropriate gain, or wiring/configuration error

Pre-Use Confirmation

1. Confirm that the current Klipper version includes load_cell / load_cell_probe support.
2. Confirm that the ADC chip, sample rate, pins, and MCU being used are consistent with the manufacturer's configuration.
3. Confirm that endstop_pin, position_min, position_max, and the Z-axis movement direction are correct.
4. Do not directly copy configurations from other pressure sensors, load cell modules, or manufacturer-specific modules to your machine.

Functional Boundaries

Load Cell probe configuration involves mechanical force, sensor range, and ADC sampling. Without complete product instructions, it is not recommended for ordinary customers to modify their printers to use a Z probe; configuration errors can lead to nozzle crashing into the bed, Z-axis skipping steps, or sensor overload.

Diagnostic Command

If the configuration is provided by the product documentation and Klipper starts normally, you can first execute:

LOAD_CELL_DIAGNOSTIC

Result Interpretation:

1. Measured samples per second should be close to the configured sample rate; if the difference is significant, prioritize checking the configuration and communication.
2. Saturated samples should be 0; if not 0, it indicates possible sensor overload, excessive gain, or configuration mismatch.
3. Unique values should not be 1 for a long period; if there is almost no change, it is commonly due to wiring, ADC, or sampling configuration errors.
4. When the sensor reading changes following the safe test method provided by the product documentation, Sample range should show an observable change; if there is no change, stop auto-home and probing actions first.

Power Off Before Inspection

Before checking the Load Cell, ADC module, toolboard interface, harness crimping, or reconnecting the sensor, please completely turn off the printer and disconnect the power supply. Do not plug or unplug sensor harnesses or touch terminals while the power is on.

No trigger on probe after full movement

Error Message: No trigger on probe after full movement appears when homing or probing using [load_cell_probe].

Common Causes:

• Incorrect probe threshold or homing direction configuration, causing the Z-axis not to move towards the sensor's force application direction.
• position_min / position_max limits causing the Z-axis to traverse the entire allowed travel range before making contact.
• Load Cell readings do not change, or the ADC chip is not sampling stably.
• Insufficient mechanical rigidity, improper sensor preload, or the nozzle does not reliably contact the force application point.

Solutions:

1. First execute LOAD_CELL_DIAGNOSTIC to confirm that the sensor reading changes with light touch.
2. Verify the Z-axis direction, position_min, position_max, and homing_positive_dir.
3. Check if the [load_cell_probe] threshold and ADC configuration come from the product documentation for the current hardware.
4. If the diagnostic reading is abnormal, stop the homing test, power off the printer, and check the wiring, connectors, and sensor installation.
5. Before retesting, ensure there is no obvious looseness or jamming in the nozzle, heatbed, and sensor structure while the printer is powered off.

Motion-related Troubleshooting: No trigger on probe after full movement

Invalid ads1220 reset state

Error Message: Invalid ads1220 reset state.

Common Causes:

• The ADS1220 chip is not powered on correctly or has not completed initialization.
• Incorrect ADC communication pins, SPI bus, or chip select configuration.
• The current Klipper / firmware does not support the used ADC or Load Cell configuration method.
• Module wiring, harness crimping, or toolboard interface is abnormal.

Solutions:

Power Off Before Inspection

Before checking the ADS1220 module, SPI/I2C harness, chip select wire, or toolboard interface, please completely turn off the printer and disconnect the power supply. Do not plug/unplug modules or rearrange wiring order while the power is on.

1. Verify the ADC module model, communication method, and the configuration section name from the product documentation.
2. Check if cs_pin, spi_bus, or software SPI pins match the actual wiring.
3. Confirm that the firmware for the MCU connected to the ADC has been re-flashed and matches the host Klipper version.
4. If this feature comes from a third-party branch or manufacturer-customized Klipper, first confirm the current system still includes the corresponding module.
5. Cross-test by replacing the finished harness or module; do not let ordinary customers solder, fly wires, or modify the ADC module themselves.