code: public ModbusRequest buildRestartCommunicationsOption(int serverAddress, boolean clearLog) throws ModbusNumberException {
          return buildDiagnostics(DiagnosticsSubFunctionCode.RESTART_COMMUNICATIONS_OPTION, serverAddress, clearLog ? DiagnosticsRequest.CLEAR_LOG : 0);
      }
docs: The remote device serial line port must be initialized and restarted, and all of its
  communications event counters are cleared. If the port is currently in Listen Only Mode, no
  response is returned. This function is the only one that brings the port out of Listen Only
  Mode. If the port is not currently in Listen Only Mode, a normal response is returned. This
  occurs before the restart is executed.
  When the remote device receives the request, it attempts a restart and executes its power–up
  confidence tests. Successful completion of the tests will bring the port online.
  A request data field contents of FF 00 hex causes the port’s Communications Event Log to be
  cleared also. Contents of 00 00 leave the log as it was prior to the restart.
  
  @param serverAddress a slave address
  @param clearLog      causes the port’s Communications Event Log to be cleared
  @return DiagnosticsRequest instance
  @throws ModbusNumberException if server address is in-valid