Play back data from log file
ROS Toolbox / ROS
The Read Data block plays back rosbag logfiles by outputting the most
recent message from the log file based on the current simulation time. You must load a rosbag
log file (
.bag) and specify the
Topic in the block
mask to get a stream of messages from the file. Messages on this topic are output from the
file in sync with the simulation time.
In the Read Data block mask, click Load log file data
to specify a rosbag log file (
.bag) to load. In the Load Log
File window, specify a Start time offset, in seconds, to
start playback at a certain point in the file. Duration specifies how
long the block should play back this file in seconds. By default, the block outputs all
messages for the specific
Topic in the file.
IsNew— New message indicator
New message indicator, returned as a logical. If the output is
1, then a new message was loaded from the rosbag file at that
time. This output can be used to trigger subsystems for processing new messages
Msg— ROS message
ROS message, returned as a nonvirtual bus. Messages are output in the order they are stored in the rosbag and synced with the simulation time.
Topic— Topic name to extract from log file
Topic name to extract from log file, specified as a string. This topic must exist in the loaded rosbag. Click the Load rosbag file Use Select ... to inspect the topics available and select a specific topic.
Sample time— Interval between outputs
–1(default) | scalar
Interval between outputs, specified as a scalar. In simulation, the sample time follows simulation time and not actual wall-clock time.
This default value indicates that the block sample time is inherited.
For more information about the inherited sample time type, see Specify Sample Time (Simulink).