ophyd

1.11.1 verified Fri May 01 auth: no python

Ophyd is a hardware abstraction library for the Bluesky framework with an emphasis on EPICS. It provides a device-oriented API for control system signals, motors, area detectors, and more. Currently at version 1.11.1, it is under active development with regular releases. Requires Python >=3.8.

pip install ophyd

Common errors

error ModuleNotFoundError: No module named 'epics' ↓

cause Missing PyEpics package for EPICS communication.

fix

pip install pyepics or conda install -c conda-forge pyepics

error TimeoutError: Connection to PV '...' timed out after 2.00 seconds ↓

cause EPICS PV not available or network issue.

fix

Verify PV exists and network is reachable. Increase timeout via 'timeout' parameter in EpicsSignal(..., timeout=10).

error ImportError: cannot import name 'Component' from 'ophyd.device' ↓

cause Direct import from internal module instead of top-level.

fix

Use 'from ophyd import Component'

error AttributeError: 'EpicsSignal' object has no attribute 'set_and_wait' ↓

cause Deprecated function removed or renamed.

fix

Replace with 'signal.set(value)' and use status objects or await.

Warnings

breaking Inophyd v1.10.0, the EPICS backend API changed. Fallback backends are now class-based instead of function-based. Code using custom backends may need updates. ↓

fix Review migration notes at https://blueskyproject.io/ophyd/upcoming-changes.html

deprecated The function 'set_and_wait' is deprecated since v1.7.0 and may be removed in future releases. ↓

fix Use Signal.set() with await or status events instead.

gotcha EpicsSignal and EpicsMotor require a connection to the EPICS PV. If the PV does not exist, connecting will block until timeout (default 2.0 seconds in v1.10.5+). ↓

fix Set 'wait_for_connection=False' and check connection status manually, or increase timeout via timeout kwarg.

gotcha DeviceStatus reports a fraction of 1.0 once complete as of v1.7.0. Code relying on a fraction of 0.0 after completion will break. ↓

fix Adjust code to handle updated fraction value.

breaking In v1.8.0, isort was adopted; imports may need reorganization. Also, setuptools-scm replaced manual versioning. ↓

fix No direct breakage, but import ordering may require changes if using strict flake8 or isort checks.

deprecated The 'user_v2' module is removed as of v1.10.0. Use the standard 'ophyd' API instead. ↓

fix Replace 'from ophyd import user_v2' with direct imports from ophyd.

Install

conda install -c conda-forge ophyd

Imports

EpicsSignal
```
from ophyd import EpicsSignal
```
Simple EPICS PV signal
EpicsMotor
```
from ophyd import EpicsMotor
```
EPICS motor record device
Device
```
from ophyd import Device
```
Base class for composite devices
Signal
```
from ophyd import Signal
```
Base signal class for internal or simulated signals
Component
wrong
```
from ophyd.device import Component
```
correct
```
from ophyd import Component
```
Component is re-exported at top-level; importing from ophyd.device is deprecated.

DynamicDeviceComponent

wrong

from ophyd.device import DynamicDeviceComponent

correct

from ophyd import DynamicDeviceComponent

Same as Component; prefer top-level import.

Quickstart

Basic usage: create an EPICS signal and motor, define a composite device with Components, and wait for connections.

from ophyd import EpicsSignal, EpicsMotor
from ophyd import Component, Device

# Create a simple EPICS signal
sig = EpicsSignal('MYPV:PREFIX', name='my_signal')
sig.wait_for_connection()
print(sig.get())

# Create a motor
motor = EpicsMotor('MYMOTOR:PREFIX', name='my_motor')
motor.wait_for_connection()
print(motor.user_readback.get())

# Define a composite device
class MyDevice(Device):
    x = Component(EpicsMotor, 'X')
    y = Component(EpicsMotor, 'Y')
    detector = Component(EpicsSignal, 'Det')

dev = MyDevice('MYDEV:', name='my_device')
dev.wait_for_connection()
print(dev.detector.get())