Created method for returning raw system time. (dmroeder#57)

* Created method for returning raw system time.
Human-readable time is now a separate method (but still the default for GetPLCTime()) and uses this new method.

* Added missing "self"

* Added back lines accidentally deleted.
Refactored to remove separate GetRawPLCTime() routine - now GetPLCTime() is still a single
method but with keyword raw=False (default).

pylogix/eip.py

@@ -105,11 +105,11 @@ def MultiRead(self, tags):
         '''
         return _multiRead(self, tags)
 
-    def GetPLCTime(self):
+    def GetPLCTime(self, raw=False):
         '''
-        Get the PLC's clock time
+        Get the PLC's clock time, return as human readable (default) or raw if raw=True
         '''
-        return _getPLCTime(self)
+        return _getPLCTime(self, raw)
 
     def SetPLCTime(self):
         '''
@@ -348,7 +348,7 @@ def _multiRead(self, tags):
             err = 'Unknown error {}'.format(status)
         raise ValueError('Multi-read failed: {}'.format(err))
 
-def _getPLCTime(self):
+def _getPLCTime(self, raw=False):
     '''
     Requests the PLC clock time
     ''' 
@@ -379,6 +379,8 @@ def _getPLCTime(self):
     if status == 0:
         # get the time from the packet
         plcTime = unpack_from('<Q', retData, 56)[0]
+        if raw:
+            return plcTime
         humanTime = datetime(1970, 1, 1) + timedelta(microseconds=plcTime)
         return humanTime
     else: