FAQ

Short answers, with links to the long ones. Select a question to open it.

Hardware

Which motors work with the Tercio S1?

Bipolar stepper motors with four wires, 1.8° or 0.9°, with a rear shaft for the encoder magnet. The S1 drives up to 1770 mA RMS per coil and mounts on the back of a NEMA 17. Larger motors work within that current, with less torque than their rating. See Mounting.

What magnet do I need?

A diametrically magnetised neodymium magnet, typically 6 mm across and 2–3 mm thick, glued centred on the rear shaft. An axial magnet does not work. S1-ready motors have one fitted.

Can the S1 run without the Tercio FD?

Yes, in step/dir mode. You need the adapter once to calibrate and configure it; after that, with Follow step/dir input and Enable at power-up saved, it runs from a motion controller alone.

Can I use 5 V step/dir signals?

Not directly. The inputs are 3.3 V logic; use a level shifter. See Wiring.

Does the S1 know its position after a power cut?

Within one turn: at power-up it reads the angle from the saved zero, between −½ and +½ turn. Whole turns are not remembered, so home the axis if it may have moved further.

The bus

How many drivers can share a bus?

Up to 127 node IDs. The practical limit is bus time: at 100 Hz, each driver’s telemetry takes about 3 % of the bus, so twenty drivers use about half of it. With many drivers, lower the Telemetry rate.

How long can the bus be?

Keep it within a few metres, twisted all the way, with short stubs. The 2.5 Mbit/s data phase is what limits it.

Can I use another CAN-FD adapter?

Yes, for your own software: it is plain CAN-FD with 11-bit IDs. Set 500 kbit/s arbitration (sample point about 75 %) and 2.5 Mbit/s data with bit-rate switching (sample point about 74 %). Tercio Control and the Tercio libraries need the Tercio FD, because they use its serial framing.

Can classic CAN devices share the bus?

No. A classic CAN controller treats CAN-FD frames as errors and disturbs the bus.

Software

Which browsers run Tercio Control?

Chrome, Edge and other Chromium browsers on desktop computers, which support Web Serial. The demo mode runs in any browser.

Is the firmware open source?

Yes. The S1 firmware, the Tercio FD firmware, Tercio Control and the libraries are on GitHub. The S1 firmware is GPL-3.0.

Why are positions in turns?

One turn is the natural unit for a rotary axis: it is exact for any gearing or microstep setting, and converts to degrees or radians with one multiplication. Tercio Control and the libraries convert for you.

Is there a ROS or LinuxCNC integration?

Not yet. The Python library and the protocol are the building blocks for one.

Buying

Where can I buy Tercio modules?

At the Tercio Labs store. It opens on 1 December 2026; join the list there to get an email when it does.