Technical Manual

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Terminology

For this document we will refer to SLB/SLB-EXT as 1st generation (abbreviated to “gen”) SLB controllers. Consequently, SLB-LITE/SLB-EXT V2 are referred to as 2nd gen controllers. If not specified, assume we are talking about SLB-LITE/SLB-EXT V2.

Differences between 1st and 2nd Gen SLBs

We have highlighted some of the major differences and improvements between the two generations of SLBs below. More details can be found in the specific sections further in this document.

• Upgraded to a modern RP2350 microcontroller with better reliability, simplified flashing process, and improved driver support
• Integrated motor signal, motor power, and limit switch connectors into one locking connector and cable for each axis
• In 1st gen controllers when the E-stop was triggered, power was cut to the motors, requiring a power cycle at the controller to restore functionality. Now, the E-stop doesn’t cut power, it turns OFF the motors enable signal – meaning motors still get disabled but you don’t need to power cycle anymore to get functionality
• E-stop is now directly attached to the board, and programmable E-stop action buttons have been removed, however a separate remote E-stop can be connected
• Ethernet port is moved to the expansion board, purchased separately from the main board
• Power distribution is completely re-designed to meet electrical safety requirements (Class 2 power)
• New firmware, which changes how certain functions are handled, as well as the new or modified firmware settings between the 1st and 2nd gen SLBs.
  • Use this official grblHAL reference document for the latest updated firmware settings https://grblhal.org/docs/reference/settings/

Machine-to-Controller Compatibility

By default, the SLB-LITE was designed for the LongMill MK3 and the SLB-EXT V2 was designed for the AltMill MK2. This means that any other configuration will require some modification, whether that be to the firmware, machine profile/settings, and/or electrical components. Please note that our team cannot provide full technical support for these modifications.

Sienci Labs CNCs

Controller	Machine	Status	Notes / Required Changes
SLB-LITE	LongMill MK3	🟢 Default, current	Current standard pairing
SLB	LongMill MK3	🟡 Needs changes	Downgrade motors to open loop and switch to AltMill motor cables
SLB-LITE	LongMill MK2.5	🔴 Not recommended	No significant performance improvements
SLB-LITE	AltMill	🔴 Not recommended	Power insufficient for larger CNCs
SLB-EXT	LongMill MK3	🟡 Needs changes	Switch to AltMill motor cables or use motor connector adapters
SLB-EXT	AltMill	🟢 Default, current	Current standard pairing
SLB-EXT V2	AltMill	🔵 Default, upcoming	Upcoming standard pairing
SLB-EXT V2	LongMill MK3	🔴 Not recommended	No need for that amount of power

3rd Party CNCs

SLB-LITE

• Designed for 1.2Nm motors on all axes, 24V motor power
• Suitable for smaller, beginner CNCs like Shapeoko/X-Carve/Genmitsu
• If using controller for 3rd party CNC, we recommend purchasing the Closed Loop Motor Kit which contains the SLB-LITE, compatible motors and their cables

SLB-EXT V2

• Designed for 2Nm motors on X and Y axes, 1.2Nm on Z-axis, 48V motor power
• Suitable for larger CNCs like Onefinity 4×8, Elite
• If using controller for 3rd party CNC, this requires custom wiring for motor and limit switch connections (Molex MicroFit 3.0 2x7p connector)
  • Can wire into the connector to pass power through the board and out from the motors, or skip the power passthrough which would require motor connector adapters

Dimensions

Below are drawings of the top case and board, showing the part dimensions in millimeters.

Power

One of the major differences between the SLB-LITE and SLB-EXT V2 is how power is distributed through the board to the motors.

• The SLB-LITE distributes power directly from a single power supply input, going through the board to each of the five (5) motor inputs. Motor power is switched on and off using the controller power switch.
• The SLB-EXT V2 distributes power through six (6) independent input channels – five (5) dedicated to motor outputs, one (1) for the controller’s onboard power requirements.
  • This reduces the maximum power through each independent output at a time, ensuring a high level of safety alongside individual circuit protection provided from the 6-channel power supply. Since power remains electrically isolated from the controller, the motor power is switched on and off by the power supply.

Status LEDs

On the controllers, there are 12 LEDs in a circle that will automatically light up and animate based on the machine’s current state. Below is a chart listing the colour and animation for each state, and what the states mean.

State	Description	Colour & Animation
Idle	Machine ready, waiting for commands	⚪ Solid white
Cycle / Running	G-code is running, like a job or a macro	🟢 Solid green
Jogging	Machine is jogged	🟢 Green comet with short bright head and dim tail
Hold	Job is paused	🟡 Yellow pulse between dim and bright, full ring
Safety Door	Spindle and coolant disabled, waiting on switch to close (advanced)	🟡 Yellow blink, alternating half-rings
Homing	Homing is in progress	🔵 Blue sweep, mirrored from opposite sides
Check Door	Safety door detected as opened, door state initiated (advanced)	🩵 Cyan checkerboard, rotating
Alarm	An alarm is triggered	🔴 Red chase with fading tail
E-stop	E-stop is triggered	🔴 Red blink, full ring
Tool Change	Tool change is in progress	🟣 Magenta dotted pattern, rotating
Sleep	De-energizes motors, spindle and coolant until reset	⚫ Solid grey

You may find it helpful in understanding how the machine responds and processes commands. If the machine is not in Idle state, you may need to clear or wait until the current state has elapsed to process other commands. For example, if the machine is in Homing, you won’t be able to jog the machine until the homing process is completed. If the machine is in Alarm, then the alarm needs to be cleared to proceed.

Additionally, there are lights next to the I/O which can indicate whether the specific functionality is behaving correctly, in real-time.

E-stop

When activated, the E-stop LED on the board turns ON, as…

1) the enable signals for the motors turn OFF, and
2) both the enable and PWM signals for the spindle/laser turn OFF, completely deactivating these components on a hardware level.

This functionality is controlled by any of these four (4) inputs:

• The physical, NC (normally closed) E-stop button that’s installed on top of the enclosure
• An input for an optional, NO (normally open) E-stop button; this is useful if the controller is mounted far away from the machine/user
• A power monitoring feedback loop
  • Incoming voltage is checked by the protection chip
  • If voltage is within an acceptable range, power is delivered as normal and the controller sends the “power good” PGOOD signal [PGOOD LED ON]
  • Otherwise, in cases of undervoltage, overvoltage or overcurrent, the chip cuts power to the controller, and the PGOOD signal turns OFF [PGOOD LED OFF], thus triggering the E-stop
• STP pin connected to GND on the expansion board; this is useful for hooking up a sensor that needs to trigger an E-stop, e.g. spindle overheat sensor

Optional E-stop

If you connected the extra E-stop on the board, the expected behaviour is as follows:

• Optional E-stop released AND onboard E-stop released – machine is ready to use
• Optional E-stop pressed AND/OR onboard E-stop pressed – E-stop triggered

Motors and Limit Switches

The controllers have five (5) connections for X, Y1, Y2, Z and A-axis motors, as well as limit switches on each axis. On our machines, the boards support NEMA 23 closed loop motors with external drivers, STEP/DIR/EN/AL signals. Limit switches are inductive-style, with 5V/Sig/GND signals, and can be NO or NC since the signal can be inverted in the firmware settings.

A-axis

The controllers are able to run the A-axis independently from the other axes, meaning it can support a true 4th axis system. We recommend using the Sienci Labs Vortex, as the workflows on gSender were designed with the Vortex in mind. Using 3rd party 4th axis systems is possible, however it will require firmware settings adjustment and potentially custom wiring.

Ring and Rail Lights

Connect compatible WS2812 LED lights to the controller’s Ring and Rail ports to add lighting to your machine. You can connect up to two strips, with a combined maximum of 60 LEDs and 2 A.

By default, these lights change colour and animation to match the machine’s status, just like the 12 lights around the E-stop button. You can also set them to white or green, turn them off, or adjust their brightness.

Ring and Rail lights always work together. Both ports receive the same signal, so you cannot control them independently.

Choose What Your Lights Do

Use the following G-code commands to change the lighting:

What you want to do	Command
Make Ring and Rail lights follow the machine’s status	M356 P1 Q0
Set Ring and Rail lights to white	M356 P1 Q1
Turn Ring and Rail lights off	M356 P1 Q2
Set Ring and Rail lights to green	M356 P1 Q3
Make the lights around the E-stop follow the machine’s status	M356 P0 Q0
Make all lights follow the machine’s status	M356 Q0

Turning the lights off does not turn off the machine or disable the E-stop.

Adjust Brightness

Brightness uses a scale from 0 to 255, where 0 is the lowest setting and 255 is full brightness.

Brightness	Command
25%	M356 S64
50%	M356 S128
100%	M356 S255

These commands adjust the overall LED brightness.

Understand the Commands

Each part of the command controls a different setting:

Command part	What it controls
M356	Changes the lighting settings
P1	Applies the lighting mode to Ring and Rail lights
P0	Applies the lighting mode to the 12 lights around the E-stop
No P value	Applies the setting to all lights
Q0	Automatic: follows the machine’s status
Q1	White
Q2	Off
Q3	Green
S0–S255	Brightness, from lowest to highest

For example, M356 Q0 S64 makes all lights follow the machine’s status at approximately 25% brightness.

Note: For advanced users: Please note that if you use M150 command to manually program on the pixel level, the first pixel offboard is 13, not 0, since the first 1-12 pixels refer to the LED ring around the E-stop. Additionally, you can use M150 R, M150 G, and M150 B for the colours.

Spindle

Spindle Connection

The SPINDLE port supports both 5 V PWM and Modbus to control a compatible spindle and its variable frequency drive (VFD).

Spindle Port Pins

Pin	Function	Description
1	Spindle detect	Detects a connected spindle through a connection to ground on Pin 5. Automatic detection is still in development and is not yet available.
2	E-stop output	Signals when the hardware E-stop is active by connecting Pin 2 to ground on Pin 5 through an optocoupler. This output is not currently used in the spindle setup.
3	Modbus A	Used with Pins 4 and 5 for Modbus communication.
4	Modbus B	Used with Pins 3 and 5 for Modbus communication.
5	Ground (GND)	Ground connection shared by the control signals.
6	PWM	Provides the 5 V PWM control signal, used with Pin 5.

Choose a Control Method

We recommend Modbus if your VFD supports it, as it provides more robust communication between the controller and VFD.

Sienci spindles using the H-100 VFD can be configured through the Accessory Installation wizard in gSender.

Using a Third-Party VFD

Some third-party VFDs can work with the controller, but they require manual setup. You will need the manufacturer’s VFD manual to adjust the settings on both the VFD and in gSender.

See the MODVFD Setup guide for setup instructions.

VFDs that may be compatible include:

• H-100
• Huanyang v1
• Huanyang P2A
• Durapulse GS20
• Yalang YS620
• Nowforever

Compatibility is not guaranteed, as models and product versions can vary. Our team can provide general setup guidance, but using a third-party VFD is a modification made at your own risk.

Does your VFD require a 0–10 V signal?
The controller provides 5 V PWM, not a 0–10 V analog signal. If your VFD does not accept 5 V PWM, use Modbus if supported, or a compatible PWM-to-0–10 V analog signal converter.

Laser

The LASER port of the controller supports 5V PWM laser diode accessories, with either 2-pin (GND, PWM) or 3-pin (GND, PWM and Enable) inputs.

Set Up Your Laser

1. Check your version of gSender, and the controllers firmware version.

   What to check	Minimum version
   gSender	1.6.0 or newer
   Controller firmware	20260318 or newer

   ✅ The image below shows firmware 20260525, which meets the requirement.

   
   

2. Download the Laser Config File (20260318 and up), then load it in gSender. It will automatically apply the firmware settings needed for your laser.

3. Press Run Job. Your controller will disconnect.

4. Reconnect back to gSender and on the main screen, open the Spindle/Laser tab at the bottom right corner. In the dropdown, select PWM2, this is the laser output. You can only control one output at a time.

   
   

5. Switch the toggle to Laser. Wear your laser safety glasses. Then once you are ready, press Laser Test to check that the laser activates!

For more details on the laser functionality on gSender, see This Page.

Probe/Touch Plate

You can connect a Sienci Labs touch plate, or a standard block-style touch plate with compatible connectors to the PROBE port on the controller.

For step-by-step instructions on installing and using the Sienci Labs AutoZero touch plate, see this page https://resources.sienci.com/view/addons-autozero/

3rd Party Touch Plate

3rd Party Touch Plate

Set up your touch plate in gSender by navigating to Config → Probe and adjusting the settings for your plate.

Next, check that the controller detects the touch plate correctly:

1. Keep the plate and magnet separated. The probe should be inactive.
2. Touch the magnet to the plate. Check gSender’s controller status for Pn:P, indicating that the probe is triggered.
3. Separate them again. The P should disappear from the status.

If the probe status behaves in reverse, toggle Invert Probe Pin in Config and test again.

Note: The yellow LED beside the PROBE port indicates whether the physical probe circuit is closed. Its behaviour is not affected by the inversion setting.

To learn how gSender handles the probing process, see This Page.

TLS

Short for “tool length sensor,” the TLS is a common CNC accessory that automates zeroing in the Z-axis – this is especially helpful if you have long, complicated jobs that require multiple end mills.

If you have the Sienci Labs TLS, go here to set it up using the Accessory Installation wizard on gSender https://resources.sienci.com/view/addons-tls/#gsender-setup

If you have a 3rd party TLS, keep reading!

3rd Party TLS

If your TLS wiring is not labelled, check the manufacturer’s documentation to identify the Power (5V), Signal, and Ground (GND) wires before connecting it to the controller.

For a simple mechanical switch, a multimeter can help identify the signal and ground connections by checking continuity as the switch is pressed. This method does not apply to inductive sensors, which require power to operate.

Make sure your TLS is compatible with the controller’s 5V input before connecting it.

Once you’ve mounted the TLS and plugged it into the controller at the TLS port, press it and see if the orange TLS light on your controller responds.

If TLS is NO → Orange light turns ON
The light will be ON when TLS is pressed

If TLS is NC → Orange light turns OFF
The light will stay OFF if TLS is disconnected

If you find the TLS is not behaving as expected, you may need to invert the probe signal as follows: On gSender, in Config, go to the Probe heading. Find Invert Probe Inputs ($6), and toggle the Toolsetter option to the opposite setting. Press Apply Settings then turn OFF/ON the controller to have the setting take effect.

Then manually configure the firmware settings as outlined below:

• Go back to the main Carve screen on gSender
• Jog the machine towards you and install your longest end mill into the spindle. This is to ensure there is enough clearance during tool changing.
• Home the machine. You must have limit switches installed to do homing, otherwise you cannot use the TLS.

• Jog the machine so the end mill is positioned over the center of your TLS, slightly above the metal button, about 0.5-1″ (10-20mm).
• Go back to Config. Under the Tool Changing tab, adjust the following settings:
• gSender strategy
  • Select “Fixed Tool Sensor”
• Fixed sensor location
  • Press the Grab button
• First tool behaviour
  • “Prompt for first tool”
• Set tool change location
  • Toggle ON

• Press Apply Settings.
• Go back to the main Carve screen. Jog the machine to a place where you can change out your end mill safely and easily, like at the front left of your machine. Then jog all the way up on the Z-axis – this ensures you can access the tool easily while changing it out.
• In Config, navigate back to Tool Changing tab, then find the Manual tool change location
  • Press the Grab button
  • Press Apply Settings.
• In Config, go to the Spindle/Laser tab and adjust these settings:
  • Spindle/laser controls
  • Toggle ON
  • Spindle on delay ($394)
  • 11 OR whatever your manufacturer states
  • Spindle off delay ($539)
  • 11 OR whatever your manufacturer states

• Press Apply Settings, then turn OFF/ON the controller.
• Re-connect to gSender.

Now that you have the TLS set up, familiarize yourself with how gSender handles tool changes with a TLS – see it in action in this video https://youtu.be/fswJHOhdZgE?si=rvBe-N1_WLb1euFX&t=610 .

Aux

Short for “auxiliary,” the AUX ports provide 5V output, up to 250mA per port, for low-power accessories such as compatible relays, solid-state relays (SSRs), or small solenoids.

For higher-power accessories, such as LED strips, the AUX port can control a suitable relay that switches an external power supply. Do not connect LED strips directly to the AUX port unless their power requirements are within the port’s limits.

To set up an auxiliary accessory, go to Config, and navigate to Accessory Outputs heading. There, you can customize what M commands control the accessory. Apply the settings, then turn OFF/ON the controller. Now, you can switch the accessory ON/OFF in several ways; injecting the g-code into your job file via post processor, setting up macro buttons or automations [https://resources.sienci.com/view/gs-macros/] , or entering the g-code manually into the console.

• Spindle/Laser Enable (M3/M4): turns the output on with M3 or M4, and off with M5
• Mist Enable (M7): turns on/off with M7/M9
• Flood Enable (M8): turns on/off with M8/M9
• M62-M65 Only: available as a backup to control each port with a unique M command:
  • Turn on/off with M62/63 (but wait in line before running)
  • Turn on/off immediately with M64/65
  • Enter $pins into the console to see which pins are which

Expansion

The expansion board will be available for both the SLB-LITE and SLB-EXT V2. The main features include ethernet connectivity, four (4) accessory (AUX) outputs, and ATC spindle support.

The pinout for the header connector is shown below:

Comes with Power, UART, Neopixel, I2C, Shift Register Expansion, E-stop, SPI, Ethernet SPI Support pins (IRQ and CS), one spare MCU IO, 4 spare shift register outputs and GND.

Into it we can plug our EXTV2 Expansion which offers

• Ethernet
• 4 x AUX Output
• ATC Spindle support

Ethernet https://resources.sienci.com/view/gs-using-gsender/#ethernet-connection

Connectors List

Power

• SLB-LITE: 5.5mm OD, 2.1mm ID barrel jack (24-48V, 4A)
• SLB-EXT V2: Molex MicroFit 3.0 2x6P connector, with isolated channels powering each motor (24-48V, 4A max per channel)

Connectivity

• USB-C connector for serial connection to controller
• MicroSD card slot for local file storage and macro functionality

Motors & Limit Switches

• Molex MicroFit 3.0 2x7P connector

Tool Length Sensor (TLS)

• Phoenix-style 3.81-3P pluggable terminal connector (5V, NC input)

Probe/Touchplate

• Phoenix-style 3.81-2P pluggable terminal connector (NO input)

Auxiliary (Aux)

• Phoenix-style 3.81-2P pluggable terminal connector (5V output)

Laser

• Phoenix-style 3.81-3P pluggable terminal connector (5V PWM output, Enable signal)

Ring LED

• JST XHP-3P connector (5V, Neopixel Signal Output)

Rail LED

• JST XHP-3P connector (5V, Neopixel Signal Output)

Optional External E-stop

• Phoenix-style 3.81-2P pluggable terminal connector (NO input)

Spindle/Router

• RJ12 connector for PWM and MODBUS communication with routers and spindle VFDs

Expansion:

• 26 Pin IDC type connector

Open Source

The SLB-LITE/SLB-EXT V2 project is licensed as “CERN-OHL-S”. This means that if you use our publicly available code and/or designs, you must license your code and hardware changes under the same license, giving attribution to us. Additionally if you use our firmware on other hardware, then that hardware should have the same license too.

You can read more about the license here [https://gitlab.com/ohwr/project/cernohl/-/wikis/Documents/CERN-OHL-version-2] , in the LICENSE file contained in most repos, or in the License headers of the affected files.

Find the board design, firmware and other documents in the following repos:

SLB-LITE: https://github.com/Sienci-Labs/SuperLongboard-Lite

SLB-EXT V2: https://github.com/Sienci-Labs/SuperLongboard-EXT-V2