Adds a new handling for reconnects.

measurement_main.py

     global modem_serial_obj
     print_message("Reonnect modem with provider {} ...".format(provider))
     if hard:
-        if modem_serial_obj.is_open:
-            modem_serial_obj.write(b'at+COPS?\r\n')
-            sleep(NR_SERIAL_RESPOND_TIME)
-            modem_serial_obj.write(b'AT+QENG="servingcell"\r\n')
-            sleep(NR_SERIAL_RESPOND_TIME)
+        print_message("Performing HARD reconnect...")
+        try:
+            if modem_serial_obj.is_open:
+                modem_serial_obj.write(b'at+COPS?\r\n')
+                sleep(NR_SERIAL_RESPOND_TIME)
+                modem_serial_obj.write(b'AT+QENG="servingcell"\r\n')
+                sleep(NR_SERIAL_RESPOND_TIME)
+        except:
+            if not modem_serial_obj.is_open:
+                print_message("Serial port is closed.")
+            else:
+                print_message(
+                    "Something went wrong while writing to serial."
+                )
     else:
         os.system("/root/connect-modem.py -s")
         sleep(5)