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Int16MultiArray messages with rosserial_tivac

asked 2016-03-19 19:54:03 -0500

wintermute gravatar image

Hello All,

I am trying to send Int16MultiArray messages with rosserial_tivac using the code in this here.

There is the statement: = (int*) malloc(sizeof(int) * 8);

which causes compile error:

sketch_mar20b.cpp:23:17: error: cannot convert 'int' to 'int16_t {aka short int*}' in assignment

in order to compile I had to change it to: = (int16_t*) malloc(sizeof(int) * 8);

which will compile, and the rosserial node will declare the published topic (my_array_topic in my case) - but unfortunately, rostopic echo /my_array_topic will not display anything.

Also I have not been able to find good documentation and examples about these MultiArray messages, so it would be great if someone could point me out in the right direction for learning more about them.

Best Regards, C.

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answered 2017-03-20 06:32:29 -0500

vmatos gravatar image

You also need to set the length of your array in the message you're publishing. I don't recall if there is an explicit rosserial tutorial with this information. But you can check a ros_lib message definition, e.g.: build/rosserial_tivac_tutorials/ros_lib/std_msgs/Int16MultiArray.h

There's a data_lengthfield in the message definition. It doesn't publish the data, because your data_length==0.

You're missing my_array.data_length = 8; before publishing.

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Asked: 2016-03-19 19:54:03 -0500

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Last updated: Mar 20 '17