pncconf -don't crash if no serial ports are found.

I just added a default port designation if none are found.
It was report from a rasberry pi system.

Author: c-morley

src/emc/usr_intf/pncconf/pages.py

@@ -877,7 +877,7 @@ def external_finish(self):
         self.d.gs2_vfd_deaccel = self.w.gs2_vfd_deaccel.get_value()
         model = self.w.gs2_vfd_device_name.get_model()
         active = self.w.gs2_vfd_device_name.get_active()
-        self.d.gs2_vfd_port = model[active][0]
+        self.d.gs2_vfd_port = '/dev/ttyS0';model[active][0]
         model = self.w.gs2_vfd_baud.get_model()
         index = self.w.gs2_vfd_baud.get_active()
         self.d.gs2_vfd_baud = model[index][1]
@@ -975,6 +975,9 @@ def on_joysticktest_clicked(self, *args):
 
     def search_for_serial_device_name(self):
         match = os.popen("""ls /sys/class/tty/*/device/driver | grep 'driver' | cut -d "/" -f 5""").read().split()
+        if len(match) <1: return
+        return
+        print(len(match))
         model = self.w.gs2_vfd_device_name.get_model()
         model.clear()
         for item in match: