Multi State Limit Sensors

This is the next revision of my Hall Limit Sensors. Based on more feedback from existing users I have created an enhanced Limit Sensor. They are 5% larger than the previous form factor, however, they offer more functionality and can be configured by the user. You now have the option of running them in the Normally Closed mode (the default) or Normally Open mode. They can be used with controllers that operate at higher voltages up 30 volts and higher.  

Features:

• Can be configured for Normally Open (NO) or Normally closed (NC), by the end user.
• In the Normally Closed state they can be daisy chained, more on this later.
• Can handle higher current sensing, as used in CNC Routers with complex controllers and separate controllers.
• Three connection options: Vertical connector, Horizontal connector or Solder directly to the board.

Specifications:

• Sensor Dim: 15.24 x 21.08 x 7.57 (mm with vertical plug) height is 6.07 with horizontal plug.
• Mount Dim: 19.69 x 25.55 x 9.57 (mm with vertical plug) height is 8.07 with horizontal plug.
• Sensing voltage: 60 Volts @ 500mA / 30 Volts @ 1000mA
• Supply voltage: 3.3 – 5 Volts
• Power draw: 15mA @ 3.3 Volts / 33mA at 5 Volts
• Plug with wire (length 95mm) included with Horizontal and Vertical connectors.    

Improvements:

• This new version now leverages an optical relay allowing for increase power sensing. It also isolates the sensing circuit from the power side of the circuit. This provides short circuit protection between the two circuits.?
• Improved control logic on a single chip. This offers consistent performance in power fluctuations. The logic chip is more resistant to power fluctuations increasing the overall performance consistency.?
• NC / NO Functionality: Unlike the previous version these sensors are Normally Closed (NC) by default. By adding a drop of solder on the two pads changes the sensor to Normally Open (NO).?
• When using the sensors in the Normally Closed (NC or Default) configuration you can serially connect multiple sensors. In this mode the sensors can offer circuit integrity alarming. In this mode if there is a break in the wiring they will alarm and stop your CNC from moving with a broken circuit. ? These improvements give flexibility for a full range of CNC controllers, they can be used on GRBL Controllers, TinyG, Xcarve, and Break Out Boards (BOB). The final flexibility I built into the sensors is the connectivity. The connector is a four pin Micro JST connector, the sensor can be ordered with a vertical or horizontal plug. You can also forgo the connector and solder directly to the sensor. This is strictly a user preference choice.

* * Please note that if you need the simplicity of a Normally Open (NO) mechanical Limit Switch you can use this version or the older version. If you have question please feel free to contact me. **

Why Hall Sensors:

Magnetic Sensors (Hall Effect Sensor) are used in place of mechanical switches for CNC Routers 3D Printers or any movement control system. They are highly accurate and offer consistent repeatable results with extremely low tolerances.   Hall effect sensors are used for proximity switching, positioning, speed detection, and current sensing applications. In its simplest form, the sensor acts as an on/off switch when it comes in proximity of a magnetic field.   I originally designed these sensors to be used on my ShapeOko CNC router with the standard GRBL controller (supplied with ShapeOko 1 and 2) they will work on either 3.3 or 5 volts. This new version expands the range of machines they can be used on.

In fact these sensors can be used any where position detection is required such as a lids, windows, doors and anything where position detection is needed. Feel free to ask me about your situation.  

How do they differ from mechanical limit switches?

• There are no moving parts to wear out and fail.
• They offer a much higher accuracy than a mechanical switch.
• They offer more flexibility in placement/configuration.
• They have three connections (Sensor, Positive and Negative). Where the mechanical limit switches just have two (Sensor, Negative).
• They are cool, lights to show current alarm status. Green = Normal, Red = Alarm  

How Do They Work:

The functionality is very simple, when the sensor comes in proximity of a magnetic field, the sensor trips: - NC: The circuit is opened and the flow of electricity is disabled. - NO: The circuit is closed and the flow of electricity is enabled. This is the same as the mechanical limit switches that come with desktop CNC machines. - The sensors can be configured as Normally Open (NO) by connecting two solder pads with a drop of solder. See the documentation for the details on how to configure and wire the sensors.

When the sensor trips:

• Green LED turns off.
• Red LED turns on.
• In the case of a CNC router movement stops.  

When the magnet is moved away from the sensor the state is reversed:

• Red LED is turned off.

• Green LED is turned on.

• The sensitivity and precision of the magnetic sensor make it an excellent choice for accuracy and repeatability, especially where tolerances of .001 mm or less are required. The sensor will have no impact to the controller since it requires very little power.   

Connecting The Sensor

Connecting the sensor is very easy there are two wires for power and two wires for the sensor circuit. As noted in the picture of the sensor with the wires plugged in   - Red wire goes to Positive - Black wire goes to the Negative - Yellow wire for sensor positive side - Blue or White wire for sensor negative side    The Vertical and Horizontal connectors include a wired plug. The wires on the plug are about 95mm. At the time of purchase you can forego the wire connector and plug, and solder directly to the board.

The following are videos of the new and old sensors:

- Axis Demonstration Limit Sensor 6B

• Grbl Shield Demo (original sensor) https://www.youtube.com/watch?v=F3XpLWkOgSw

I have a limited quantity of sensors with Purple PCB and white lettering. If you prefer those over the black, send me an email after you submit an order and I will confirm availability.