Frequently Asked Questions¶

How do I fix the “unable to communicate with master!” error?¶

Solution:

Is your VIPER running and active? If no, please turn it on.

Is your ROS_MASTER_URI set correctly? If no, please set the ROS_MASTER_URI to the location of your VIPER.

Can you contact the address specified in the ROS_MASTER_URI?

echo $ROS_MASTER_URI
http://<VIPER_IP>:11311
ping <VIPER_IP>
ping: unknown host <VIPER_IP>

If you get the “unknown host” error, please check your network settings or change the ROS_MASTER_URI to a resolvable address.

Please refer to VIPER Discovery.