Modify AnalogInput initialization, add exception handling.

Author: jburhenn

myDevices/plugins/analog.py

@@ -3,19 +3,19 @@
 """
 import json
 from myDevices.plugins.manager import PluginManager
-from myDevices.utils.logger import info
+from myDevices.utils.logger import info, debug
 
 
 class AnalogInput():
     """Reads data from an analog input."""
 
-    def __init__(self, adc_name):
+    def __init__(self, adc):
         """Initializes the analog input.
         
         Arguments:
-            adc_name: Name of analog-to-digital converter plugin in the format 'plugin_name:section'
+            adc: Analog-to-digital converter plugin ID in the format 'plugin_name:section', e.g. 'cayenne-mcp3xxx:MCP'
         """
-        self.adc_name = adc_name
+        self.adc_name = adc
         self.adc = None
         self.read_args = {}
         self.pluginManager = PluginManager()
@@ -30,7 +30,11 @@ def set_adc(self):
     def read_value(self, channel, data_type=None):
         """Read the data value on the specified channel."""
         self.set_adc()
-        value = getattr(self.adc['instance'], self.adc['read'])(channel, data_type=data_type, **self.read_args)
+        try:
+            value = getattr(self.adc['instance'], self.adc['read'])(channel, data_type=data_type, **self.read_args)
+        except ValueError as e:
+            debug(e)
+            value = None
         return value
 
     def read_float(self, channel):