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How to publish raw data to /diagnostics topic?

asked 2021-11-14 06:47:41 -0600

Kevin1719 gravatar image

Hi, I have been reading about Diagnostics tools in ROS and knew how to setup to analyze the raw data from robot hardware. But I'm wondering how to publish those data to /diagnostics topic, so that I can use them to analyze and re-publish to /diagnostics_agg topic?

Can anyone explain the process of getting raw data from robot hardware and how to config it to use in ROS? Thank you so much.

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answered 2021-11-20 21:07:27 -0600

Kevin1719 gravatar image

I figured out that first you need a code to read port signals (e.g. battety current or motor temperature), then publish those data to relevant topics. Once you have raw data in the system, you need a node to subscribe for those data and then reformat it to diagnostic_msgs/DiagnosticArray type to republish them to /diagnostics topic so you can use it with the diagnostic package tools.

There is a really good example for filling the fields in DiagnosticArray type here.

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answered 2021-11-14 18:00:13 -0600

Geoff gravatar image

You need to publish diagnostic information from your robot using the messages and services defined in diagnostic_msgs. You should make a node that reads the raw data from the robot hardware and fills in these messages, then publishes them to the diagnostics topic.

There is a good tutorial on setting up the aggregator available here.

For a real example, see the PR2 power board node, which publishes diagnostic information for the power distribution board.

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Thank you for your answer. But I have to be honest, I'm not really good in coding, I got lost in the code you gave and didn't know where to start with. The only problem I have now is how to convert raw data to diagnostic_msgs/DiagnosticArray, will I have to do it manually or is there a tool for the job? Since it quite an exhausting process.

Kevin1719 gravatar image Kevin1719  ( 2021-11-15 04:06:27 -0600 )edit

I can't tell you how to convert the raw data because I do not know what format it is in.

If you are struggling to understand the code, then I think you might be better off learning coding better first.

Geoff gravatar image Geoff  ( 2021-11-15 16:51:31 -0600 )edit

For example, I received battery_voltage value from the hardware, so I want to re-format it as a DiagnosticArray message, with the 'name' field is "battery_voltage", and the 'value' field is the value of the battery voltage recieved, shoud I do it by re-format the data for every type of raw data, or is there another way to do it faster?

Kevin1719 gravatar image Kevin1719  ( 2021-11-15 21:03:39 -0600 )edit

That's how you have to do it.

Geoff gravatar image Geoff  ( 2021-11-16 17:49:10 -0600 )edit

Okay, thanks for your enthusiasm.

Kevin1719 gravatar image Kevin1719  ( 2021-11-20 20:57:01 -0600 )edit

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Asked: 2021-11-14 06:47:41 -0600

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Last updated: Nov 20 '21