RTU slave simulator device not known and exception

[leissbua]

Describe the bug

I do not know to what serial device to connect when using slave simulator and end up with an exception when sending a payload.

To Reproduce Steps to reproduce the behavior:

Start slave simulator RTU, it is not know what virtual device comes up that can be connected to.

It is not known on what serial port the slave simulator is running. when simply setting rtu and sending a modbus payload i get an exception:

om.intelligt.modbus.jlibmodbus.exception.ModbusIOException: com.intelligt.modbus.jlibmodbus.serial.SerialPortException: purejavacomm.PureJavaIllegalStateException: JTermios call returned -1 at class purejavacomm.PureJavaSerialPort line 1106
	at com.intelligt.modbus.jlibmodbus.net.ModbusConnectionSerial.openImpl(ModbusConnectionSerial.java:62)
	at com.intelligt.modbus.jlibmodbus.net.ModbusConnection.open(ModbusConnection.java:45)
	at com.intelligt.modbus.jlibmodbus.master.ModbusMaster.connectImpl(ModbusMaster.java:74)
	at com.intelligt.modbus.jlibmodbus.master.ModbusMaster.connect(ModbusMaster.java:88)
	at modbusmechanic.ModbusMechanic.generateModbusMessage(ModbusMechanic.java:353)
	at modbusmechanic.ModbusMechanic.generateModbusRTURequest(ModbusMechanic.java:314)
	at modbusmechanic.PacketFrame.transmitPacket(PacketFrame.java:815)
	at modbusmechanic.PacketFrame.transmitPacketButtonActionPerformed(PacketFrame.java:677)
	at modbusmechanic.PacketFrame.access$1500(PacketFrame.java:31)
	at modbusmechanic.PacketFrame$16.actionPerformed(PacketFrame.java:448)
	at java.desktop/javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1967)
	at java.desktop/javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2308)
	at java.desktop/javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:405)
	at java.desktop/javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:262)
	at java.desktop/javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:279)
	at java.desktop/java.awt.Component.processMouseEvent(Component.java:6635)
	at java.desktop/javax.swing.JComponent.processMouseEvent(JComponent.java:3342)
	at java.desktop/java.awt.Component.processEvent(Component.java:6400)
	at java.desktop/java.awt.Container.processEvent(Container.java:2263)
	at java.desktop/java.awt.Component.dispatchEventImpl(Component.java:5011)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2321)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4843)
	at java.desktop/java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4918)
	at java.desktop/java.awt.LightweightDispatcher.processMouseEvent(Container.java:4547)
	at java.desktop/java.awt.LightweightDispatcher.dispatchEvent(Container.java:4488)
	at java.desktop/java.awt.Container.dispatchEventImpl(Container.java:2307)
	at java.desktop/java.awt.Window.dispatchEventImpl(Window.java:2772)
	at java.desktop/java.awt.Component.dispatchEvent(Component.java:4843)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:772)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
	at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:715)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:95)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:745)
	at java.desktop/java.awt.EventQueue$5.run(EventQueue.java:743)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:742)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
Caused by: com.intelligt.modbus.jlibmodbus.serial.SerialPortException: purejavacomm.PureJavaIllegalStateException: JTermios call returned -1 at class purejavacomm.PureJavaSerialPort line 1106
	at com.intelligt.modbus.jlibmodbus.serial.SerialPortPJC.open(SerialPortPJC.java:102)
	at com.intelligt.modbus.jlibmodbus.net.ModbusConnectionSerial.openImpl(ModbusConnectionSerial.java:60)
	... 44 more
Caused by: purejavacomm.PureJavaIllegalStateException: JTermios call returned -1 at class purejavacomm.PureJavaSerialPort line 1106
	at purejavacomm.PureJavaSerialPort.checkReturnCode(PureJavaSerialPort.java:1307)
	at purejavacomm.PureJavaSerialPort.<init>(PureJavaSerialPort.java:1106)
	at purejavacomm.CommPortIdentifier.open(CommPortIdentifier.java:159)
	at com.intelligt.modbus.jlibmodbus.serial.SerialPortPJC.open(SerialPortPJC.java:83)
	... 45 more

Can you clarify to what serial port i have to connect or is this a bug?

Thanks a lot and sorry if i simply dont get it.

regards

Michael