ZWO EAF module for pyobs

This module provides a pyobs driver for the ZWO Electronic Auto Focuser (EAF). It exposes the focuser as a pyobs module implementing IFocuser and ITemperatures, allowing remote focus control and temperature monitoring via the pyobs communication layer.

Requirements

Python

• Python 3.11 or later
• pyobs-core 2.0 or later

System

The C++ extension is built against the ZWO EAF SDK (bundled) and requires libudev at both build and runtime. Install the development package before building:

sudo apt install libudev-dev

The runtime library (libudev.so.1) ships with most Linux distributions and is usually already present; the -dev package provides the linker symlink needed during the build.

Installation

pip install pyobs-zwoeaf

Or from source:

uv sync

udev rule

To allow access to the EAF USB device without root privileges, add a udev rule. Create /etc/udev/rules.d/99-hidraw.rules with the following content:

SUBSYSTEM=="hidraw",MODE="0660",GROUP="plugdev"

Then add your user to the plugdev group and reload the rules:

sudo usermod -aG plugdev $USER
sudo udevadm control --reload-rules && sudo udevadm trigger

Configuration

Add the module to your pyobs configuration:

focuser:
  class: pyobs_zwoeaf.EAFFocuser
  device_number: 0      # USB device index (0 for the first EAF)
  max_steps: 60000      # maximum step count
  backlash: 0           # backlash compensation in steps
  direction: true       # motor direction (true = left rotation)
  sound: true           # beep when motion starts

CLI tool

A simple interactive terminal tool for direct hardware access is included, useful for commissioning and manual adjustments:

pyobs-zwoeaf