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MDM Module Blockage Detection

Features Overview​

The FLY-LLL PLUS Buffer can be used with the FLY-MDM Filament Breakage/Blockage Sensor to achieve real-time monitoring and automatic handling of extruder blockage status.

Core Functions​

  • Blockage Detection: The MDM module monitors the buffer's filament status and detects blockages
  • Unified Breakage/Blockage Handling: The MDM module is also responsible for filament breakage detection, with signals sent via the buffer

Important Note: When using the MDM module, all breakage/blockage detection signals are sent to the mainboard through the buffer, and the mainboard cannot distinguish the signal source (breakage or blockage).

Firmware Requirements​

  • Buffer firmware version must be V1.1.5 or higher

Hardware Wiring​

1. MDM Module to Buffer Connection​

The MDM module communicates directly with the buffer to detect blockage status:

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2. Buffer to Mainboard Connection​

The mainboard sends signals to the buffer

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3. Buffer Filament Breakage Detection Wiring​

The buffer's filament breakage detection must be connected to the mainboard; otherwise, it will not function properly

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Specific Connection Methods:

Buffer PinFunction DescriptionConnection Suggestion
STEPExtruder step signal monitoringConnect to an unused PWM, RGB, or 12864 interface on the mainboard
DIRExtruder direction signal monitoringConnect to an unused limit switch interface on the mainboard

Tip: The BL-Touch servo port can also be used for STEP signal monitoring.

Klipper Configuration​

Pre-configuration Preparation​

Before adding the MDM module configuration, ensure the following are correctly configured:

  • Basic extruder configuration
  • Basic buffer function configuration
  • Note: Filament breakage detection now follows the path: MDM module → Buffer → Mainboard

1. Buffer Monitoring Configuration (for Blockage Detection)​

Add the following configuration to the Klipper configuration file (e.g., printer.cfg) to monitor the extruder status:

[extruder_stepper buffer_monitor]
extruder: extruder           # Name of the associated main extruder
step_pin: PE10               # Replace with the actual pin connected to buffer PA5
dir_pin: PD4                 # Replace with the actual pin connected to buffer PB11
rotation_distance: 17.472    # Replace with your extruder's actual value
gear_ratio: 50:10            # Replace with your extruder's actual gear ratio
microsteps: 16               # Replace with your extruder's actual microsteps
full_steps_per_rotation: 200 # Standard stepper motor is 200 steps/revolution

Complete Configuration Example​

# Main Extruder Configuration
[extruder]
step_pin: PB13
dir_pin: PB12
enable_pin: !PB14
microsteps: 16
rotation_distance: 17.472
gear_ratio: 50:10
nozzle_diameter: 0.4
filament_diameter: 1.75
heater_pin: PA1
sensor_type: ATC Semitec 104GT-2
sensor_pin: PC1
control: pid
pid_Kp: 21.527
pid_Ki: 1.063
pid_Kd: 108.982
min_temp: -235
max_temp: 350

[extruder_stepper buffer_monitor]
extruder: extruder
step_pin: PE10      # Connected to buffer PA5
dir_pin: PD4        # Connected to buffer PB11
rotation_distance: 17.472
gear_ratio: 50:10
microsteps: 16
full_steps_per_rotation: 200

[filament_switch_sensor Material_breakage_detection]
pause_on_runout: true
switch_pin: ^PA0   # Please replace with the actual pin you are using
runout_gcode:
    PAUSE
    RESPOND MSG= "Filament breakage detected, print paused"
insert_gcode:
    RESPOND MSG="Filament inserted, ready to continue printing"
event_delay: 2.0    # Event trigger delay (seconds)
pause_delay: 2.0     # Pause command delay (seconds)
debounce_delay: 2.0  # Debounce delay (seconds)

Buffer Configuration​

Notes
  • If gear_ratio is not present in the extruder configuration, change Drive Gear Teeth and Driven Gear Teeth to 1
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Parameter Description​

Function DescriptionConfiguration Command (Please input in the serial tool)Default ValueUnitRemarks
View all current parameters
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--Send the command to read all current configurations.
Set motor pulse count
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916-Set the number of pulses required for the motor to move per millimeter.
Set encoder detection distance
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1.73mmSet the filament movement distance represented by each encoder signal.
Set operation timeout
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60000msSet the automatic stop time when no trigger is detected to prevent continuous extrusion.
Set error scaling factor
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2.0-Allowable Error = encoder value X scale value.
Example: 1.73 * 2.0 = 3.46 mm
Set speed control command
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260mmSet the buffer running speed, maximum 600 (rpm). Firmware needs to be updated to V1.1.1.

Operation Notes:

  1. Command Format: In the "Configuration Command" column of the table above, the entire line of command (e.g., steps 916) is the content that needs to be entered in full.
  2. Sending Method: After entering the command in the send area of the serial assistant, click the Send button.
  3. Automatic Save: After the command is sent successfully, the parameters take effect immediately and are saved automatically. No additional save operation is required.
  4. Confirm Configuration: After modifying any parameter, you can send the info command to query all current parameters to verify if the configuration is correct.
Notes
  • Remember to configure the buffer via the link below after setting the parameters
  • Buffer Configuration

Functional Testing​

1. Connection Test​

  1. Complete the connection between the MDM module and the buffer
  2. Complete the signal line connection between the buffer and the mainboard
  3. Confirm all connections are secure

2. Full Process Test​

  1. Start a test print
  2. Simulate a blockage condition (operate carefully)
  3. Observe:
    • Whether the MDM module detects the issue
    • Whether the buffer forwards the signal
    • Whether the mainboard receives the signal
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