Pre-defined Messages

Sensor-based messages are contained within the directory:

Defining Custom Messages

ROS messages are defined in .msg files.

An automatic MD5 sum of the .msg file is created and is checked when nodes try and publish/subscribe to topics. Nodes can only communicate when both the message type and MD5 sums match.

NOTE: If you get an error similar to:

this could be

The Header

ROS messages may include a special header. This can contain a time stamp and frame ID.

MD5 Checksums

If the message types are not the same, you will normally get a runtime error on launch similar to: