code: private int stringToFlow(String flowcontrol) {
          if (ModbusUtil.isBlank(flowcontrol) || flowcontrol.equalsIgnoreCase("none")) {
              return AbstractSerialConnection.FLOW_CONTROL_DISABLED;
          }
          else if (flowcontrol.equalsIgnoreCase("xon/xoff out")) {
              return AbstractSerialConnection.FLOW_CONTROL_XONXOFF_OUT_ENABLED;
          }
          else if (flowcontrol.equalsIgnoreCase("xon/xoff in")) {
              return AbstractSerialConnection.FLOW_CONTROL_XONXOFF_IN_ENABLED;
          }
          else if (flowcontrol.equalsIgnoreCase("rts/cts")) {
              return AbstractSerialConnection.FLOW_CONTROL_CTS_ENABLED | AbstractSerialConnection.FLOW_CONTROL_RTS_ENABLED;
          }
          else if (flowcontrol.equalsIgnoreCase("dsr/dtr")) {
              return AbstractSerialConnection.FLOW_CONTROL_DSR_ENABLED | AbstractSerialConnection.FLOW_CONTROL_DTR_ENABLED;
          }
          return AbstractSerialConnection.FLOW_CONTROL_DISABLED;
      }
docs: Converts a <tt>String</tt> describing a flow control type to the
  <tt>int</tt> which is defined in SerialPort.
  
  @param flowcontrol the <tt>String</tt> describing the flow control type.
  @return the <tt>int</tt> describing the flow control type.