C94 UC300ETH Multifunction CNC Breakout Board with Spindle Control, Relays & Optoisolated I/O

C94 UC300ETH Multifunction CNC Breakout Board

The C94 is an integration board for the UC300ETH Ethernet motion controller. The controller mounts directly onto the C94, and the board turns its five IDC26 ports into screw terminals for stepper or servo drives, a VFD, limit and home switches, a probe, an E-stop, coolant, vacuum, and whatever else your machine needs. It adds the parts a bare controller does not have: optoisolated inputs, three relays, PWM-based 0-10V spindle speed control, a microcontroller-based safety charge pump, and E-stop and driver-fault monitoring. One 10-30VDC supply powers the whole assembly.

Quick Answer

• What it is: A multifunction CNC breakout board that the UC300ETH-5LPT motion controller plugs directly into. No ribbon cables between the controller and the board.
• What it does: Gives you screw terminals for 6 axes of step and direction, 18 optoisolated inputs, 16 outputs, 3 relays, 0-10V spindle control, E-stop, charge pump, and driver-fault monitoring, plus 3 expansion ports for more I/O.
• Best for: CNC routers, plasma tables, lasers, and mill retrofits running UCCNC, Mach3, or Mach4 on steppers or step/direction servos.
• Important: The UC300ETH controller is not included with this listing. It is shown installed on the board in the photos. If you need both, the UC300ETH + C94 bundle ships with the controller already installed on the board.

C94 or C76? The short version

Both boards carry the UC300ETH and share the same port layout, relays, spindle control, and safety charge pump. The C94 is the simpler, lower-cost board with fixed screw terminals and heavier open-collector outputs (2A at up to 60V). The C76 adds VFD-fault monitoring, dedicated 5V high-speed encoder inputs, pluggable terminals, and plug-in RJ45 drive cabling through the C34 connector board family.

• Pick the C94 for a stepper-driven router, plasma table, or laser where you want clean terminal wiring at the lowest price.
• Pick the C76 for servo builds, spindle encoders (rigid tapping or threading), VFD alarm handling, or a production cabinet you will service often.

Key Features

• Built for the UC300ETH: The UC300ETH-5LPT mounts directly onto the C94. The Ethernet jack stays accessible on top of the board, and the board supplies the controller's power.
• 6-axis step and direction on screw terminals: Port 1 brings out 12 outputs, enough for X, Y, Z, A, B, and C step and direction pairs, with status LEDs on every signal.
• 18 optoisolated inputs on the board: 5 inputs on Port 1 and 13 on Port 2 accept 5-24VDC signals from limit switches, home switches, probes, NPN or PNP sensors, and operator buttons.
• Three built-in relays: Two electromechanical relays with NO and NC contacts for spindle on/off and direction, plus a third general-purpose relay that a jumper assigns to Port 2 pin 16 or 17. Each relay is rated 2A at 125VAC or 2A at 60VDC.
• PWM-based spindle speed control: Converts the controller's PWM signal into a 0-10V analog speed command for a VFD. The board generates its own isolated supply for the spindle control circuit.
• Heavy-duty open-collector outputs: Port 2 pins 1, 14, 16, and 17 are open-collector outputs rated up to 60VDC and 2A, so they can drive 24V relay coils, solenoids, and indicator lamps directly. (Jumpers assign some of these pins to the on-board relays and spindle control when you use those functions.)
• Safety built in: Dedicated E-stop terminal tied to the enable line, microcontroller-based safety charge pump (SCHP) that keeps outputs off until the control software is live, and a driver-fault (ERR) input for drive alarm signals.
• Three IDC26 expansion ports: LPT3 and LPT5 input expansion ports and an LPT4 output expansion port let you add relay boards, additional breakout boards, or an MPG pendant and use all 49 inputs and 36 outputs the UC300ETH offers.
• Analog I/O: The controller's two analog inputs and two analog outputs are available on a 16-pin header.
• Single power supply: Runs on 10-30VDC and generates the 5V logic supply on board. A 24V DIN rail supply is the usual choice.
• Screw-on terminals and status LEDs everywhere: Every input, output, relay, and the enable state has an LED, which makes first power-up and troubleshooting much faster.
• DIN rail mountable: Add the DIN Rail Support for C94 to clip the board (with the controller on it) onto 35 mm DIN rail.

Why CNC Builders Use the C94

A bare UC300ETH gives you five 26-pin headers and nothing else. Every switch, drive, and relay would need its own ribbon-to-terminal adapter, and you would still have no spindle speed output, no charge pump, and no relays. The C94 solves all of that on one board, and it does it at a lower price than any other full-featured UC300ETH carrier we sell.

• Wire the whole machine with a screwdriver, no ribbon cables or adapter boards
• Controller, inputs, outputs, relays, and spindle control on one mounting footprint
• Optoisolation between the machine wiring and the controller's logic
• Charge-pump and E-stop logic in hardware, not just in software
• Outputs strong enough to switch 24V loads without an extra relay board
• Room to grow through the three expansion ports

Best Applications

• UCCNC control cabinets for CNC routers and plasma tables
• Mach3 and Mach4 retrofits moving off the parallel port
• DIY CNC router builds on stepper motors and drivers
• Plasma tables using an external torch height controller such as the THC-1 or THC-2
• Laser and engraving machines that need relay and PWM control
• Mill and lathe retrofits on step/direction stepper or servo drives
• Machines that need E-stop, charge pump, and driver-fault monitoring in hardware

Technical Specifications

Software and Setup

• User's manual: Pinouts, jumper settings and wiring samples for limit sensors, axes, E-stop and the VFD are in the C94 user's manual (PDF).
• UCCNC: Install your UCCNC license, run the UC utility to set a fixed IP and whitelist the controller, then run the C94 profile installer below. It configures the pinouts and functions the board supports.
• Mach3: Install the UC300ETH plugin, then start from the sample C94 XML profile below. The sample covers step and direction for 4 axes, E-stop, safety charge pump, homes and limits, spindle speed, and a probe on Port 1 pin 15.
• Mach4: Supported through the UC300ETH Mach4 plugin. Use the same pin map as the Mach3 profile.
• First power-up: Wire the E-stop, power the board, and confirm the green enable LED comes on with the E-stop closed before connecting drives. Leave the charge-pump jumper off until the software is talking to the controller, then turn it on so the software controls enable.
• Licenses for Mach3 and Mach4 are available separately. UCCNC licenses are tied to the controller.

Compatibility Note

• This board is for the UC300ETH Ethernet motion controller. It does not work with the Ethernet SmoothStepper, PoKeys57CNC, AXBB-E, or USB controllers. For the SmoothStepper, use the C25XP.
• This listing is the C94 board only. The UC300ETH, drives, motors, power supply, VFD, switches, and wiring are sold separately.
• The analog port is not isolated. Keep it within 0-5V.
• Power the board from a regulated 10-30VDC supply capable of at least 2A. The board generates the 5V the mounted UC300ETH needs, so no separate controller supply is required.
• If you are moving from an older breakout board, check that your drive signal levels (5V TTL or open collector) and input commons match the C94's jumper options before wiring.

Need the UC300ETH Controller Too?

Most new builds need both. The UC300ETH + C94 bundle ships with the controller already installed on the board, so you unpack it, mount it, and start wiring.

• Controller installed and matched: No guessing about header alignment or which controller fits.
• One supply, one footprint: Ethernet motion control and terminal wiring in a single DIN-mountable assembly.
• Costs less than buying the two separately: The bundle comes in under the price of the board and controller bought one at a time.

Recommended Add-Ons

• DIN Rail Support for C94 - clips the C94 (with the controller on it) onto 35 mm DIN rail. One support carries the whole assembly.
• 35 mm DIN Rail, 12 inch - slotted aluminum rail for the cabinet back panel.
• 24V 3.2A DIN Mount Power Supply - covers the board's 2A requirement with headroom for sensors and relay coils.
• C36S Quad Relay Board - four more relays for coolant, vacuum, dust collection, and lights, driven from the outputs or an expansion port.

What You Receive

• C94 UC300ETH Multifunction CNC Breakout Board (Rev. 2)
• Screw terminals for 6 axes, 18 inputs, 16 outputs, 3 relays, spindle control, E-stop, and power
• Three IDC26 expansion ports and one analog header
• User's manual and setup files linked below
• UC300ETH controller and DIN rail support are not included

Documents and Setup Files

• 🔗 C94 User's Manual, Board Rev. 2 (PDF): pinouts, jumpers and wiring samples
• 🔗 UCCNC Profile Installer for the C94
• 🔗 Mach3 Sample XML Profile for the C94
• 🔗 UCxx Utility Software (network setup for the UC300ETH)
• 🔗 UC300ETH Plugin for Manual Installation in Mach3
• 🔗 Variable Speed Control (0-10V VFD wiring) PDF
• 🔗 Configuration of Control Software PDF
• 🔗 UC300ETH Controller Manual

Before You Order

• Choose this board if you already own a UC300ETH and want screw-terminal wiring, relays, spindle control, and charge-pump safety at the lowest price.
• Choose the UC300ETH + C94 bundle if you need the controller too.
• Choose the C76 instead if you need VFD-fault monitoring, encoder inputs, pluggable terminals, or RJ45 drive cabling.
• This is not a standalone motion controller and it does not connect to motors by itself. It needs the UC300ETH and your stepper or servo drives.
• Add the DIN Rail Support for C94 if the board is going on DIN rail. The support does not fit the C76.