code: public void addDeviceAppender(final String deviceTargetName, final Class<?> deviceClassName,
              final String loggingDeviceName) throws DevFailed {
          if (rootLoggerBack != null) {
              logger.debug("add device appender {} on {}", deviceTargetName, loggingDeviceName);
              final DeviceAppender appender = new DeviceAppender(deviceTargetName, loggingDeviceName);
              deviceAppenders.put(loggingDeviceName.toLowerCase(Locale.ENGLISH), appender);
              rootLoggerBack.addAppender(appender);
              // debug level by default
              setLoggingLevel(LoggingLevel.DEBUG.toInt(), deviceClassName);
              setLoggingLevel(loggingDeviceName, LoggingLevel.DEBUG.toInt());
              appender.start();
          }
      }
docs: Logging of device sent to logviewer device
  
  @param deviceTargetName
  @param deviceClassName
  @param loggingDeviceName
  @throws DevFailed