code: public void setResponseTimeout(int timeout) {
          try {
              getConnection().setReadTimeout(timeout);
          } catch (Exception e) {
              Modbus.log().warning(e.getLocalizedMessage());
          }
      }
docs: ModbusMaster will block for only this amount of time.
  If the timeout expires, a ModbusTransportException is raised, though the ModbusMaster is still valid.
  
  @param timeout the specified timeout, in milliseconds.