Limit Switch Related

Microswitch Limit Switch

Three-Wire Microswitch Precautions

Note

• FLY Mainboard Users Please Note: Three-wire microswitch limit switches cannot be directly connected to the FLY mainboard, as the limit switch interface on the mainboard already provides 5V power. Direct connection will cause a 5V short circuit, damaging the mainboard, host computer, drivers, and other devices!

• Solution
  • Cut the 5V wire: Cut the 5V wire (usually red, please confirm based on actual color) corresponding to the XH2.54 terminal of the three-wire limit switch and wrap it with insulating tape to prevent short circuits.

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Microswitch Wiring Method

Notes

• Strongly Recommended: Use Normally Closed (NC) terminal (prevents crash accidents in case of wire breakage)

• Connection Requirements:

Mainboard Terminal	Function	Connection Requirements
5V	Power	🔌 Leave Unconnected
GND	Ground	✅ Must Connect
S	Signal	✅ Must Connect

• Testing Steps:

1. Set multimeter to continuity test mode (buzzer icon)

2. Test the microswitch:

   • Not Pressed: NC terminal and Common terminal should be continuous (buzzer sounds)
   • Pressed: NC terminal and Common terminal should be disconnected (silent)

3. If the result is opposite:

   • Check if the Normally Open (NO) terminal was mistakenly used
   • Check for poor contact
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Configuration Instructions

• Pull-up Resistor Requirement:

  • Most printers require enabling the pull-up resistor, which must be done by adding the ^ symbol before the pin

• Normally Closed Limit Configuration:

  • When using a Normally Closed (NC) limit switch, you must also add the ! symbol

• Below is a reference configuration

  [stepper_x]
  endstop_pin: ^!PD9

TAP

Wiring Instructions

Note

• This tutorial uses the BL-Touch interface of SHT36-V2 for demonstration
• Some TAP modules support 12V or 24V, but 5V power supply is recommended (safe)
• The middle signal port of BL-Touch cannot be used as a limit switch port!!!

Mainboard Terminal	Function	Connection Requirements
5V	Power	✅ Must Connect
GND	Ground	✅ Must Connect
S	Signal	✅ Must Connect

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Reference Configuration

• Pull-up Resistor Requirement:
• Most printers require enabling the pull-up resistor, which must be done by adding the ^ symbol before the pin

[stepper_z]
endstop_pin: probe:z_virtual_endstop
# position_endstop: -0.5        

[probe]
pin: ^sht36:PC15             # Signal Interface
x_offset: 0                  # X-axis - Sensor Offset Relative to Nozzle
y_offset: 0                  # Y-axis - Sensor Offset Relative to Nozzle
#z_offset: 0                 # Z-axis - Sensor Offset Relative to Nozzle
speed: 3.0                   # Probing Speed
lift_speed: 5                # Probe Lifting Speed
samples: 3                   # Number of Samples
samples_result: median       # Result Method (default median)
sample_retract_dist: 3.0     # Probing Retract Distance
samples_tolerance: 0.075     # Sampling Tolerance (Setting too small may increase sample count)
samples_tolerance_retries: 3 # Number of retries for tolerance exceeded
activate_gcode:
    {% set PROBE_TEMP = 150 %}
    {% set MAX_TEMP = PROBE_TEMP + 5 %}
    {% set ACTUAL_TEMP = printer.extruder.temperature %}
    {% set TARGET_TEMP = printer.extruder.target %}

    {% if TARGET_TEMP > PROBE_TEMP %}
        { action_respond_info('Extruder temperature target of %.1fC is too high, lowering to %.1fC' % (TARGET_TEMP, PROBE_TEMP)) }
        M106 S255
        M109 S{ PROBE_TEMP }
        M106 S26
    {% else %}
        # Temperature target is already low enough, but nozzle may still be too hot.
        {% if ACTUAL_TEMP > MAX_TEMP %}
            { action_respond_info('Extruder temperature %.1fC is still too high, waiting until below %.1fC' % (ACTUAL_TEMP, MAX_TEMP)) }
            TEMPERATURE_WAIT SENSOR=extruder MAXIMUM={ MAX_TEMP }
        {% endif %}
    {% endif %}

Photoelectric Limit Switch

Note

• This tutorial uses EE-SX670WR
• Sensor Type: NPN Normally Closed Switch
• Photoelectric switch uses 5V power supply
• For voltages exceeding 5V, use 12V or 24V; see the proximity switch tutorial below

Wiring Instructions

Mainboard Terminal	Function	Connection Requirements
5V	Power	✅ Must Connect
GND	Ground	✅ Must Connect
S	Signal	✅ Must Connect

• EE-SX670WR Wiring Instructions

• It is recommended to connect the Normally Closed wire to the blue wire (GND)!

  Photoelectric Switch	Function	Connection Requirements
  Brown	Power	✅ Must Connect
  Blue	Ground	✅ Must Connect
  Black	Signal	✅ Must Connect
  Pink	Normally Closed	Connect to GND for NC use

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Configuration Instructions

• Pull-up Resistor Requirement:

• Most printers require enabling the pull-up resistor, which must be done by adding the ^ symbol before the pin

• Below is a reference configuration

[stepper_x]
endstop_pin: ^PD9

Proximity Switch

Important Notes

• Using Omron proximity switch TL-Q5MC2-Z as an example, please note before operation:
• Sensor Type: NPN Normally Closed Switch
• Required Material: You need to purchase a BAT85 model diode

Wiring Steps

1. Diode Installation

• Connect the black end (cathode) of the diode to the sensor signal wire
• Connect the other end (anode) to the mainboard signal interface

2. Insulation Treatment

• It is strongly recommended to use heat shrink tubing or electrical tape to wrap exposed wire ends to prevent short circuits from contact with other devices
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Reference Configuration

• Pull-up Resistor Requirement:
• Most printers require enabling the pull-up resistor, which must be done by adding the ^ symbol before the pin
• Below is a reference configuration

[probe]
pin: ^PC0
x_offset: 0
y_offset: 25.0
z_offset: 0

Limit Switch Status Check

Preparation

• Preparation and Initial Check
• With the power safely disconnected, slowly move the print head to the center of the machine, then power on.
• Open the web console and enter the following command to verify the limit switch status:

QUERY_ENDSTOPS

• If the wiring and configuration are correct, all limit switches should show the open state.
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Testing

• Press and hold one of the limit switches (do not release it), then execute the following command again:

QUERY_ENDSTOPS

• The state of the pressed limit should change to TRIGGERED (e.g., if you press the Y limit, its state should change from OPEN to TRIGGERED).
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Result Diagnosis

• State not changed: Check the wiring of the limit switch and ensure the Pin defined in the configuration is correct.
• Insensitive Trigger: Check if the ^ symbol is present before the Pin in the configuration (e.g., ^PC0). This symbol is for the pull-up resistor; its absence may cause trigger issues.
• Reversed State: Check if the ! symbol is present before the Pin in the configuration.
  • If present, delete the symbol (e.g., change ^!PD9 to ^PD9).
  • If absent, try adding the symbol (e.g., change ^PD9 to ^!PD9).

Extended Features

If your printer does not use physical limit switches, please refer to the Guidelines for Using Without Limit Switches