Python

The pre-built python package blickfeld_qb2 is available on pypi. It contains all the necessary sources to communicate securely to a Qb2 device.

Python is recommended for rapid prototyping, data evaluation and tools. Usually, the performance is sufficient for live point cloud streaming & processing as e.g. it directly provides efficient memory-mapped numpy arrays as output. In combination with Open3D, it can cover a lot of application scenarios.

In this guide the Blickfeld Qb2 Python library will be first installed and a secure connection to a Qb2 device will be established. Then the version of the currently installed firmware is fetched from the device. Finally we take a look at asynchronous usage of the Blickfeld library.

Installing Blickfeld Qb2 Library

The python package to control the Qb2 device is called blickfeld_qb2 and can be installed from the PyPI repository with the respective command shown below:

$ pip3 install blickfeld_qb2

Connecting to Qb2

To interact with a Qb2 device, a gRPC connection must be established. For this purpose, the gRPC Channel from the blickfeld_qb2 library is used. Either the IP address or the hostname of the Qb2 device can be used to establish a connection. The connection is encrypted and authenticated by default.

Simple example which imports the blickfeld_qb2 python library and creates a communication channel to Qb2

import blickfeld_qb2
# Open a secure connection to Qb2
with blickfeld_qb2.Channel(fqdn_or_ip="qb2-xxxxxxxxx") as channel:
    # Call methods of services
    # ..

The serial_number can be passed additionally to authenticate a particular device. If not supplied, the authentication only checks if it is a Blickfeld device.

Simple API Requests

The code snippet below provides an example of connecting to Qb2 with the hostname qb2-xxxxxxxxx and retrieving information about its firmware version. In this case, the Firmware service from blickfeld_qb2.system.services namespace is used over the gRPC channel making a request get_status() to receive a response containing information about the currently installed firmware.

import blickfeld_qb2

# Open a secure connection to Qb2
with blickfeld_qb2.Channel(fqdn_or_ip="qb2-xxxxxxxxx") as channel:
    # Request the firmware status
    response = blickfeld_qb2.system.services.Firmware(channel).get_status()
    # Extract the firmware version
    firmware_version = response.status.installed_firmware_info
    # Print the firmware version
    print(firmware_version)

    # NOTE: A channel can be reused for other requests. It is not required to create a channel per request.

Every response to the service call is an object that typically comprises several nested objects following the protocol schema defined in the corresponding sections of the documentation. In this scenario, the information about the installed firmware version can be obtained via the field response.status.installed_firmware_info.

The print output should resemble the example shown below:

FirmwareInfo(label='JAKOB v1.5.0', version=Version(major=1, minor=5, revision='e87dfda0', is_release=True), allowed_downgrade_version=Version(minor=26))

Asynchronous Requests

If necessary, the Blickfeld library can also be used in a fully asynchronous mode. In the example shown below we introduce a coroutine get_firmware_version(), which opens an asynchronous gRPC channel and utilizes an asynchronous request async_get_status() to obtain the same information about the Qb2 firmware status.

import asyncio
import blickfeld_qb2

async def main():
    # Open a secure asynchronous connection to Qb2
    async with blickfeld_qb2.Channel(fqdn_or_ip="qb2-xxxxxxxxx") as channel:
        # Request the firmware status asynchronously and await for the response
        response = await blickfeld_qb2.system.services.Firmware(channel).async_get_status()
        # Get the firmware version from the response
        firmware_version = response.status.installed_firmware_info
        # Print the firmware version
        print(firmware_version)

        # NOTE: A channel can be reused for other requests. It is not required to create a channel per request.

# run couroutine on the event loop
asyncio.run(main())

To make an asynchronous request over the asynchronous channel, the desired method name should be prefixed with async_.

This coroutine can be further executed on the event loop. The print output resemble the example shown below:

FirmwareInfo(label='JAKOB v1.5.0', version=Version(major=1, minor=5, revision='e87dfda0', is_release=True), allowed_downgrade_version=Version(minor=26))