.. versionadded:: 0.13

            Execute global command (i.e., command not tied to a specific
            electrode or route).

def on_canvas_slave__global_command(self, slave, group, command, data):
        '''
        .. versionadded:: 0.13

            Execute global command (i.e., command not tied to a specific
            electrode or route).
        '''
        def command_callback(reply):
            _L().debug('%s.%s()', group, command)
            # Decode content to raise error, if necessary.
            try:
                decode_content_data(reply)
            except Exception:
                _L().error('Global command error.', exc_info=True)
        self.plugin.execute_async(group, command, callback=command_callback)