add some error handling

pysqm/main.py

@@ -95,6 +95,9 @@ else:
     print(('ERROR. Unknown device type '+str(config._device_type)))
     exit(0)
 
+if mydevice.addr == None:
+   print('ERROR: no device found for reading data')
+   exit(1)
 
 def loop():
     '''

pysqm/read.py

@@ -468,6 +468,7 @@ class SQMLE(SQM):
         except:
             print('Trying auto device address ...')
             self.addr = self.search()
+            if self.addr!=None:
                print(('Found address %s ... ' %str(self.addr)))
                self.port = 10001
                self.start_connection()
@@ -667,14 +668,20 @@ class SQMLU(SQM):
             print(('Trying fixed device address %s ... ' %str(config._device_addr)))
             self.addr = config._device_addr
             self.bauds = 115200
+            try:
                 self.start_connection()
+            except OSError:
+                print('device ', config._device_addr, ' does not exist')
+                raise
         except:
             print('Trying auto device address ...')
             self.addr = self.search()
+            if self.addr != None: 
                 print(('Found address %s ... ' %str(self.addr)))
+
+        if self.addr != None: 
             self.bauds = 115200
             self.start_connection()
-
             # Clearing buffer
             print(('Clearing buffer ... |'), end=' ')
             buffer_data = self.read_buffer()
@@ -700,26 +707,34 @@ class SQMLU(SQM):
         os_in_use = sys.platform
 
         if os_in_use == 'linux2':
+            print('Detected Linux2 platform')
+            ports = ports_unix
+        elif os_in_use == 'linux':
             print('Detected Linux platform')
             ports = ports_unix
         elif os_in_use == 'win32':
             print('Detected Windows platform')
             ports = ports_win
+        else:
+            print('No supported platform detected -> ', os_in_use)
 
         used_port = None
         for port in ports:
+            try:
+                os.stat(port)
+            except OSError:
+                print('port ', port,' does not exist')
+                continue
+
             conn_test = serial.Serial(port, 115200, timeout=1)
             conn_test.write('ix'.encode)
             if conn_test.readline()[0] == 'i':
                 used_port = port
                 break
 
-        try:
-            assert(used_port!=None)
-        except:
+        if (used_port==None):
             print('ERR. Device not found!')
-            raise
-        else:
+
         return(used_port)
 
     def start_connection(self):