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python_device_routing.md

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Device routing

Table of Contents

Overview

Device routing is a mechanism that allows you to send commands to a specific device using the connection with the base. This is done by specifying the device_identifier when sending a command through a service. The service doesn't need to be implemented by the base.

In other words, a command can be sent to a sub device, using a service known ony by the sub device (e.g.: ActuatorConfigClient) as long as the device_identifier is specified in the command parameters.

To obtain the device_identifier you need to use the Device Manager service.

Device Manager service

Service description

The sole purpose of the Device Manager service is to return a device handle list containing handles for all devices present using the method ReadAllDevices().

Good to know

  • The device handle list returned by ReadAllDevices() is not in any specific device order
  • Device handles also have the fields device_type and order

Example

# API initialisation
device_manager = DeviceManagerClient(router)
subDevicesInfo = device_manager.ReadAllDevices()

Device Config service

Service description

The DeviceConfig service provides information about the interrogated device:

  • device type
  • firmware and bootloader version
  • model, part, and serial number
  • MAC address and
  • hardware revision

Example

# Api initialisation
device_manager = DeviceManagerClient(router)
device_config = DeviceConfigClient(router)

# Get all device routing information (from DeviceManagerClient service)
all_devices_info = device_manager.ReadAllDevices()

options = RouterClientSendOptions()
options.timeout_ms = 4000

# Use device routing information to route to every devices (base, actuator, interconnect, etc.) in the arm/base system and request their general device information
for dev in all_devices_info.device_handle:
    device_info = {}
    device_info.update( json_format.MessageToDict( device_config.GetDeviceType           (dev.device_identifier, options) ) )
    device_info.update( json_format.MessageToDict( device_config.GetFirmwareVersion      (dev.device_identifier, options) ) )
    device_info.update( json_format.MessageToDict( device_config.GetBootloaderVersion    (dev.device_identifier, options) ) )
    device_info.update( json_format.MessageToDict( device_config.GetModelNumber          (dev.device_identifier, options) ) )
    device_info.update( json_format.MessageToDict( device_config.GetPartNumber           (dev.device_identifier, options) ) )
    device_info.update( json_format.MessageToDict( device_config.GetPartNumberRevision   (dev.device_identifier, options) ) )
    device_info.update( json_format.MessageToDict( device_config.GetSerialNumber         (dev.device_identifier, options) ) )

    # Get hexadecimal representation of MAC address
    macAddress_hexstr = ""
    for b in device_config.GetMACAddress(dev.device_identifier, options).mac_address:
            macAddress_hexstr += "%02X:" % b
    macAddress_hexstr = macAddress_hexstr[:-1] # remove last ':'
    device_info.update( { "macAddress": macAddress_hexstr } )
    print("-----------------------------")

    print("-- {}: id = {} --".format(Common_pb2._DEVICETYPES.values_by_number[dev.device_type].name, dev.device_identifier))
    for key, value in device_info.items():
            print(str("%20s") % key + ": " + str(value))

Other Services

The device_identifier can be used with other services to directly interrogate a device.

Example

# API initialisation
device_manager = DeviceManagerClient(router)
vision_config = VisionConfigClient(router)

# Getting all device routing information (from DeviceManagerClient service)
allDevicesInfo = device_manager.ReadAllDevices()

vision_handles = [hd for hd in allDevicesInfo.device_handle if hd.device_type == DeviceConfig_pb2.VISION ]

if len(vision_handles) == 0:
    print("Error: there is no vision device registered in the devices info")
elif len(vision_handles) > 1:
    print("Error: there are more than one vision device register in the devices infos")
else:
    handle = vision_handles[0]

sensor_id = VisionConfig_pb2.SensorIdentifier()
sensor_id.sensor = VisionConfig_pb2.SENSOR_COLOR

intrinsic_value = vision_config.GetIntrinsicParameters(sensor_id, handle.device_identifier)

print("Width: {0}".format(intrinsic_value.width))
print("Height: {0}".format(intrinsic_value.height))
print("Principal point x: {0}".format(intrinsic_value.principal_point_x))
print("Principal point y: {0}".format(intrinsic_value.principal_point_y))
print("Focal length x: {0}".format(intrinsic_value.focal_length_x))
print("Focal length y: {0}".format(intrinsic_value.focal_length_y))