diff --git a/CHANGELOG.md b/CHANGELOG.md
index d8d0951c..2d8e91a5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ CHANGELOG for FlatCAM beta
 
 - in CNCJob UI Autolevelling - sending GCode/GRBL commands is now threaded
 - in CNCJob UI Autolevelling - Grbl Connect tab colors will change with the connection status
+- in CNCJob UI Autolevelling - GRBL Control and Sender tabs are disabled when the serial port is disconnected
 
 18.08.2020
 
diff --git a/appGUI/ObjectUI.py b/appGUI/ObjectUI.py
index 8c8fcab4..3702f907 100644
--- a/appGUI/ObjectUI.py
+++ b/appGUI/ObjectUI.py
@@ -2084,10 +2084,6 @@ class CNCObjectUI(ObjectUI):
         # self.gr_conn_tab_layout.addWidget(self.gr_conn_scroll_area)
         self.al_toolbar.addTab(self.gr_conn_tab, _("Connect"))
 
-        for idx in range(self.al_toolbar.count()):
-            if self.al_toolbar.tabText(idx) == _("Connect"):
-                self.al_toolbar.tabBar.setTabTextColor(idx, QtGui.QColor('red'))
-
         # GRBL Control TAB
         self.gr_ctrl_tab = QtWidgets.QWidget()
         self.gr_ctrl_tab.setObjectName("connect_tab")
@@ -2107,6 +2103,14 @@ class CNCObjectUI(ObjectUI):
         # self.gr_send_scroll_area = VerticalScrollArea()
         # self.gr_send_tab_layout.addWidget(self.gr_send_scroll_area)
         self.al_toolbar.addTab(self.gr_send_tab, _("Sender"))
+
+        for idx in range(self.al_toolbar.count()):
+            if self.al_toolbar.tabText(idx) == _("Connect"):
+                self.al_toolbar.tabBar.setTabTextColor(idx, QtGui.QColor('red'))
+            if self.al_toolbar.tabText(idx) == _("Control"):
+                self.al_toolbar.tabBar.setTabEnabled(idx, False)
+            if self.al_toolbar.tabText(idx) == _("Sender"):
+                self.al_toolbar.tabBar.setTabEnabled(idx, False)
         # #############################################################################################################
 
         # GRBL CONNECT
@@ -2176,7 +2180,8 @@ class CNCObjectUI(ObjectUI):
         )
         ctrl_hlay.addWidget(self.controller_reset_button)
 
-        self.com_connect_button = FCButton(_("(Dis)Connect"))
+        self.com_connect_button = FCButton()
+        self.com_connect_button.setText(_("Disconnected"))
         self.com_connect_button.setToolTip(
             _("Connect to the selected port with the selected baud rate.")
         )
diff --git a/appObjects/FlatCAMCNCJob.py b/appObjects/FlatCAMCNCJob.py
index ea22cc55..5a6e3948 100644
--- a/appObjects/FlatCAMCNCJob.py
+++ b/appObjects/FlatCAMCNCJob.py
@@ -954,9 +954,15 @@ class CNCJobObject(FlatCAMObj, CNCjob):
 
             self.app.inform.emit("%s: %s" % (_("Port connected"), port_name))
             self.ui.com_connect_button.setStyleSheet("QPushButton {background-color: seagreen;}")
+            self.ui.com_connect_button.setText(_("Connected"))
+
             for idx in range(self.ui.al_toolbar.count()):
                 if self.ui.al_toolbar.tabText(idx) == _("Connect"):
                     self.ui.al_toolbar.tabBar.setTabTextColor(idx, QtGui.QColor('seagreen'))
+                if self.ui.al_toolbar.tabText(idx) == _("Control"):
+                    self.ui.al_toolbar.tabBar.setTabEnabled(idx, True)
+                if self.ui.al_toolbar.tabText(idx) == _("Sender"):
+                    self.ui.al_toolbar.tabBar.setTabEnabled(idx, True)
             # Toggle DTR to reset the controller loaded with GRBL (Arduino, ESP32, etc)
             try:
                 self.grbl_ser_port.dtr = False
@@ -974,9 +980,15 @@ class CNCJobObject(FlatCAMObj, CNCjob):
             self.grbl_ser_port.port = port_name
             self.grbl_ser_port.close()
             self.ui.com_connect_button.setStyleSheet("QPushButton {background-color: red;}")
+            self.ui.com_connect_button.setText(_("Disconnected"))
+
             for idx in range(self.ui.al_toolbar.count()):
                 if self.ui.al_toolbar.tabText(idx) == _("Connect"):
                     self.ui.al_toolbar.tabBar.setTabTextColor(idx, QtGui.QColor('red'))
+                if self.ui.al_toolbar.tabText(idx) == _("Control"):
+                    self.ui.al_toolbar.tabBar.setTabEnabled(idx, False)
+                if self.ui.al_toolbar.tabText(idx) == _("Sender"):
+                    self.ui.al_toolbar.tabBar.setTabEnabled(idx, False)
             self.app.inform.emit("%s: %s" % (_("Port is connected. Disconnecting"), port_name))
         except Exception:
             self.app.inform.emit("[ERROR_NOTCL] %s: %s" % (_("Could not connect to port"), port_name))