[modbus] retrieve "real" serial port with "os.path.realpath"

pyheatpump/modbus.py

@@ -1,4 +1,5 @@
 #!/usr/bin/env python3
+import os
 from serial import Serial
 from serial.serialutil import SerialException
 from umodbus.client.serial import rtu
@@ -16,10 +17,15 @@ def connect():
     global serial_conn
 
     if serial_conn is None:
-        print('Connecting to serial port *{}*'.format(
-            config.get('heatpump', 'serial_port')))
+        real_serial_port = os.path.realpath(
+            config.get('heatpump', 'serial_port'))
+
+        print('Connecting to serial port *{}* ({})'.format(
+            config.get('heatpump', 'serial_port'),
+            real_serial_port))
+
         serial_conn = Serial(
-            port=config.get('heatpump', 'serial_port'),
+            port=real_serial_port,
             baudrate=config.get('heatpump', 'baudrate'),
             bytesize=8,
             parity='N',