The BridgeSubscriber will subscribe to ROS topics specified in the configuration file and then port the data to the machine tool adapter. More...

Public Member Functions
def	__init__
	Constructor for a BridgeSubscriber.
def	data_item_conversion
	A conversion function that will convert the ROS message value to the machine tool value.
def	setup_topic_data
	This function captures the topic name, type, and member attributes that are required for the ROS subscriber.
def	topic_callback
	Callback function that captures the attribute values for a ROS topic.
def	topic_listener
	Main ROS subscriber function.
Public Attributes
	adapter
	adapter_port
	config
	data_items
	di_dict
	lib_manifests
	lock
	member_names
	member_types
	msg_parameters
	msg_text
	subscribed_list
	topic_name_list
	topic_type_list
	url

Detailed Description

The BridgeSubscriber will subscribe to ROS topics specified in the configuration file and then port the data to the machine tool adapter.

Topics and topic parameters are specified by a configuration file that must be included with the main program during execution. If this file is not provided, the node will terminate with an error message indicating the need for this file.

Command line example:

bridge_subscriber.py -i bridge_subscriber_config.yaml bridge_subscriber.py -input bridge_subscriber_config.yaml

The class contains the following methods:

setup_topic_data -- utilizes introspection to set up class instance variables. topic_callback -- callback function that captures the attribute values for a ROS topic. data_item_conversion -- sets MTConnect adapter value via ROS message CONSTANT value. topic_listener -- ROS subscriber function that launches subscribers.

Definition at line 62 of file bridge_subscriber.py.

Constructor & Destructor Documentation

def bridge_subscriber.BridgeSubscriber.__init__ ( self )

Constructor for a BridgeSubscriber.

Definition at line 64 of file bridge_subscriber.py.

Member Function Documentation

def bridge_subscriber.BridgeSubscriber.data_item_conversion	(	self,
		topic_name,
		type_name,
		msg_data,
		msg_text,
		constants
	)

A conversion function that will convert the ROS message value to the machine tool value.

The conversion dictionary is provided in the configuration file.

Parameters:

topic_name,:	string defining the name of the ROS topic
type_name,:	string defining the name of the ROS topic type
msg_data,:	list of strings defining message attributes
msg_text,:	string of the entire message text (may be eliminated in future revisions)
constants,:	list of ROS topic message type CONSTANTS stored as strings

Definition at line 227 of file bridge_subscriber.py.

def bridge_subscriber.BridgeSubscriber.setup_topic_data ( self )

This function captures the topic name, type, and member attributes that are required for the ROS subscriber.

This task is completed for each topic specified in the configuration file.

This function then performs a relative import of the topic via the getattr(import_module) function. Data is stored in the following class instance attributes:

self.topic_type_list --> used for module import and msg parameters. self.member_types --> member type, not used in msg parameters, future use. self.member_names --> used for ROS subscriber msg parameters.

Definition at line 125 of file bridge_subscriber.py.

def bridge_subscriber.BridgeSubscriber.topic_callback	(	self,
		data,
		cb_data
	)

Callback function that captures the attribute values for a ROS topic.

The topic data is stored in a list of tuples, where each tuple is a (attrib_name, attrib_value) pair. To access the integer value of the attribute value, use attrib_value.val.

All data conversions between ROS and MTConnect are stored in the ROS subscriber YAML file. A separate function handles the ROS to MTConnect conversions for generic robot messages.

Parameters:

data,:	callback ROS message data from the ROS subscriber
cb_data,:	tuple containing the following parameters:
topic_name,:	string defining the name of the ROS topic
type_handle,:	class instance of the ROS topic message i.e. <class 'mtconnect_msgs.msg._RobotStates.RobotStates'>
member_set,:	list of strings defining the attribute members for the message class
msg_text,:	string of the entire message text (may be eliminated in future revisions)

Definition at line 175 of file bridge_subscriber.py.

def bridge_subscriber.BridgeSubscriber.topic_listener	(	self,
		data
	)

Main ROS subscriber function.

A new thread is created for each callback.

Parameters:

data,:	tuple containing the following parameters:
topic_name,:	string defining the name of the ROS topic
type_handle,:	class instance of the ROS topic message i.e. <class 'mtconnect_msgs.msg._RobotStates.RobotStates'>
member_set,:	list of strings defining the message attributes
msg_text,:	string of the entire message text (may be eliminated in future revisions)