I need to pass additional variables to my ROS2 subscriber callback function. I am trying to follow the help file explicity, which states:
"callback can be a single function handle or a cell array. The first element of the cell array needs to be a function handle or a string containing the name of a function. The remaining elements of the cell array can be arbitrary user data that will be passed to the callback function."
Based on this I built the following function to run my ROS2 subscriber node:
function [] = multirate_tag_sorter_test_simple()
node = ros2node("myNode",0);
myMsg = ros2message("builtin_interfaces/Time");
tableA = struct2table(myMsg, ‘AsArray’, true);
%% THE CREATING PROBLEMS —V
mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time",{@receivedMessageCallback,tableA});
%
while true
fprintf(‘Waiting for messages to arrive…n’)
pause(5);
end
function receivedMessageCallback(src,msg,inputTable)
fprintf(‘MESSAGE RECEIVED!’);
end
end
but this generates error for code generation (see end of this question). The callback works fine if I don’t try to pass additional arguments (i.e. mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time",@receivedMessageCallback). The issue I am having is that when I try to specify the callback as {@receivedMessageCallback,tableA}, I get the error message shown at the bottom of this message.
The error message states that it expects a parameter name. It seems that Coder doesn’t know that {@func,var1} is a callback function declaration. Unfortunately, callback functions are not listed in the nave-value pair list in the help file for ros2subscriber. I even tried setting the property manually after the subscriber intialization,
mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time")
mySub.NewMessageFnc = {@receivedMessageCallback,tableA};
but got an error stating that NewMessageFnc is immutable, so it must be specified in the ros2subscriber call. Is this a bug with code generation for these callbacks, or am I doing something wrong? If it is a bug, is there a work around? Thanks.
The code generation script
cfg = coder.config(‘exe’);
cfg.Hardware = coder.hardware(‘Robot Operating System 2 (ROS 2)’);
cfg.Hardware.BuildAction = ‘Build and load’;
cfg.Hardware.RemoteDeviceAddress = ‘XXX.XXX.XXX.XXX’;
cfg.Hardware.RemoteDeviceUsername = ‘XXXX’;
cfg.Hardware.RemoteDevicePassword = ‘XXXXX’;
cfg.Hardware.DeployTo = ‘Remote Device’;
cfg.Hardware.ROS2Folder = ‘/opt/ros/galactic’;
cfg.Hardware.ROS2Workspace = ‘~/uavrt_ws’;
cfg.HardwareImplementation.ProdHWDeviceType = ‘Intel->x86-64 (Linux 64)’;
cfg.RuntimeChecks = true;%Disable for final deployments.
codegen multirate_tag_sorter_test_simple -args {} -config cfg
The error message
>> multirate_tag_sorter_test_codegen_script
??? Expected a parameter name.

Error in ==> multirate_tag_sorter_test_simple Line: 7 Column: 9
Code generation failed: View Error Report

Error using codegen

Error in multirate_tag_sorter_test_codegen_script (line 22)
codegen multirate_tag_sorter_test_simple -args {} -config cfgI need to pass additional variables to my ROS2 subscriber callback function. I am trying to follow the help file explicity, which states:
"callback can be a single function handle or a cell array. The first element of the cell array needs to be a function handle or a string containing the name of a function. The remaining elements of the cell array can be arbitrary user data that will be passed to the callback function."
Based on this I built the following function to run my ROS2 subscriber node:
function [] = multirate_tag_sorter_test_simple()
node = ros2node("myNode",0);
myMsg = ros2message("builtin_interfaces/Time");
tableA = struct2table(myMsg, ‘AsArray’, true);
%% THE CREATING PROBLEMS —V
mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time",{@receivedMessageCallback,tableA});
%
while true
fprintf(‘Waiting for messages to arrive…n’)
pause(5);
end
function receivedMessageCallback(src,msg,inputTable)
fprintf(‘MESSAGE RECEIVED!’);
end
end
but this generates error for code generation (see end of this question). The callback works fine if I don’t try to pass additional arguments (i.e. mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time",@receivedMessageCallback). The issue I am having is that when I try to specify the callback as {@receivedMessageCallback,tableA}, I get the error message shown at the bottom of this message.
The error message states that it expects a parameter name. It seems that Coder doesn’t know that {@func,var1} is a callback function declaration. Unfortunately, callback functions are not listed in the nave-value pair list in the help file for ros2subscriber. I even tried setting the property manually after the subscriber intialization,
mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time")
mySub.NewMessageFnc = {@receivedMessageCallback,tableA};
but got an error stating that NewMessageFnc is immutable, so it must be specified in the ros2subscriber call. Is this a bug with code generation for these callbacks, or am I doing something wrong? If it is a bug, is there a work around? Thanks.
The code generation script
cfg = coder.config(‘exe’);
cfg.Hardware = coder.hardware(‘Robot Operating System 2 (ROS 2)’);
cfg.Hardware.BuildAction = ‘Build and load’;
cfg.Hardware.RemoteDeviceAddress = ‘XXX.XXX.XXX.XXX’;
cfg.Hardware.RemoteDeviceUsername = ‘XXXX’;
cfg.Hardware.RemoteDevicePassword = ‘XXXXX’;
cfg.Hardware.DeployTo = ‘Remote Device’;
cfg.Hardware.ROS2Folder = ‘/opt/ros/galactic’;
cfg.Hardware.ROS2Workspace = ‘~/uavrt_ws’;
cfg.HardwareImplementation.ProdHWDeviceType = ‘Intel->x86-64 (Linux 64)’;
cfg.RuntimeChecks = true;%Disable for final deployments.
codegen multirate_tag_sorter_test_simple -args {} -config cfg
The error message
>> multirate_tag_sorter_test_codegen_script
??? Expected a parameter name.

Error in ==> multirate_tag_sorter_test_simple Line: 7 Column: 9
Code generation failed: View Error Report

Error using codegen

Error in multirate_tag_sorter_test_codegen_script (line 22)
codegen multirate_tag_sorter_test_simple -args {} -config cfg I need to pass additional variables to my ROS2 subscriber callback function. I am trying to follow the help file explicity, which states:
"callback can be a single function handle or a cell array. The first element of the cell array needs to be a function handle or a string containing the name of a function. The remaining elements of the cell array can be arbitrary user data that will be passed to the callback function."
Based on this I built the following function to run my ROS2 subscriber node:
function [] = multirate_tag_sorter_test_simple()
node = ros2node("myNode",0);
myMsg = ros2message("builtin_interfaces/Time");
tableA = struct2table(myMsg, ‘AsArray’, true);
%% THE CREATING PROBLEMS —V
mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time",{@receivedMessageCallback,tableA});
%
while true
fprintf(‘Waiting for messages to arrive…n’)
pause(5);
end
function receivedMessageCallback(src,msg,inputTable)
fprintf(‘MESSAGE RECEIVED!’);
end
end
but this generates error for code generation (see end of this question). The callback works fine if I don’t try to pass additional arguments (i.e. mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time",@receivedMessageCallback). The issue I am having is that when I try to specify the callback as {@receivedMessageCallback,tableA}, I get the error message shown at the bottom of this message.
The error message states that it expects a parameter name. It seems that Coder doesn’t know that {@func,var1} is a callback function declaration. Unfortunately, callback functions are not listed in the nave-value pair list in the help file for ros2subscriber. I even tried setting the property manually after the subscriber intialization,
mySub = ros2subscriber(node,"/myTopic","builtin_interfaces/Time")
mySub.NewMessageFnc = {@receivedMessageCallback,tableA};
but got an error stating that NewMessageFnc is immutable, so it must be specified in the ros2subscriber call. Is this a bug with code generation for these callbacks, or am I doing something wrong? If it is a bug, is there a work around? Thanks.
The code generation script
cfg = coder.config(‘exe’);
cfg.Hardware = coder.hardware(‘Robot Operating System 2 (ROS 2)’);
cfg.Hardware.BuildAction = ‘Build and load’;
cfg.Hardware.RemoteDeviceAddress = ‘XXX.XXX.XXX.XXX’;
cfg.Hardware.RemoteDeviceUsername = ‘XXXX’;
cfg.Hardware.RemoteDevicePassword = ‘XXXXX’;
cfg.Hardware.DeployTo = ‘Remote Device’;
cfg.Hardware.ROS2Folder = ‘/opt/ros/galactic’;
cfg.Hardware.ROS2Workspace = ‘~/uavrt_ws’;
cfg.HardwareImplementation.ProdHWDeviceType = ‘Intel->x86-64 (Linux 64)’;
cfg.RuntimeChecks = true;%Disable for final deployments.
codegen multirate_tag_sorter_test_simple -args {} -config cfg
The error message
>> multirate_tag_sorter_test_codegen_script
??? Expected a parameter name.

Error in ==> multirate_tag_sorter_test_simple Line: 7 Column: 9
Code generation failed: View Error Report

Error using codegen

Error in multirate_tag_sorter_test_codegen_script (line 22)
codegen multirate_tag_sorter_test_simple -args {} -config cfg ros2, ros2subscriber, callback, codegen MATLAB Answers — New Questions

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