Access and Display Device Info

In this tutorial, we learn how to get device information with aravis API.

Prerequisite

• Aravis Python (included in SDK package)
• PyGObject (included in SDK package)

Tutorial

Load required modules

First of all, to load the PyGObject to use Aravis module, we need to add $SENSING_DEV_ROOT/bin (where you installed Sensing-Dev SDK).

import os
os.add_dll_directory(os.path.join(os.environ["SENSING_DEV_ROOT"], "bin"))

Now you import the module of Aravis with PyGObject.

import gi
gi.require_version("Aravis", "0.8")
from gi.repository import Aravis

why it does not work

When you see ImportError: DLL load failed while importing _gi: The specified module could not be found.

• Environment variable SENSING_DEV_ROOT is not set appropriately.
• Python version is not 3.11.

Access to devices

Now we are ready to use Aravis API. Let's start with updating the list of U3V devices that are connected to your host machine.

Aravis.update_device_list()

By updating the list, the following API should return the nubmer of the devices.

num_device = Aravis.get_n_devices()

why it does not work

If num_devices is 0, your device may have the following issues.

• The device is not connected to your host machine appropriately.
• The WinUSB is not installed on the device (Windows). See the Startup guide (Windows)
• Udev rules file is not located under /etc/udev. See the Startup guide (Linux)

Access to device infomation

Out of num_device devices, create camera object by accessing ith device.

You can get string/intefer/float values of device information with API of get_*_feature_value as follows:

for i in range(num_device):
    device = Aravis.Camera.new(Aravis.get_device_id(i)).get_device()

    devicemodelname = device.get_string_feature_value("DeviceModelName")
    width = device.get_integer_feature_value("Width")
    ...
    del device

Some examples of general keys defined in U3V devices are listed in the table below.

Feature Name	Description	Type
DeviceModelName	Name of the device	String
Width	Width of the sensor image	Integer
Height	Height of the sensor image	Integer
PayloadSize	Size of whole data transferred from sensor	Integer
PixelFormat	Pixel Format of the sensor image data	String

tip

Those feature keys and types are defined in SFNC (Standard Features Naming Convention) by emva; however, some of the devices have their own unique features or keys. To know the all accessible features, use arv-tool-0.8. See the detail in List the available GenICam features.

why it does not work

If arv-device-error-quark returns errors:

• The device may not have the key (Not found (1)): check if the feature key is correct. See the details in List the available GenICam features.
• The type was wrong (Not a ArvGcString (0) or Not a ArvGcFlaot (0)) check if the feature type is correct. See the details in List the available GenICam features.

Display the values

    print("=== device {} information ===========================".format(i))
    print("{0:20s} : {1}".format("Device Model Name", devicemodelname))
    print("{0:20s} : {1}".format("Wdith", width))

Note that all the returned value of get_*_feature_value is a string.

Close

Using the following function in Aravis can release resources that avoid memory leaks.

Aravis.shutdown()

tip

Instead of using Aravis Python API, you can also use arv-tool. See the detail in Tools from Aravis

Complete code

Complete code used in the tutorial is here.