added before and after read to visa, added PT104 device protokol

Author: trombastic

docs/device_protokol.rst

@@ -12,6 +12,7 @@ Device Protocol IDs
 - 8: SMBus
 - 9: Reserved (Jofra350)
 - 10: GPIO
+- 11: PT104
 - 8X: Custom Worker
 - 95: Reserved (Scripting)
 - 96: Reserved (Event)

pyscada/core/__init__.py

@@ -1,7 +1,7 @@
 # -*- coding: utf-8 -*-
 from __future__ import unicode_literals
 
-__version__ = '0.7.0rc16'
+__version__ = '0.7.0rc17'
 __author__ = 'Martin Schröder'
 
 default_app_config = 'pyscada.apps.PyScadaConfig'

pyscada/visa/device.py

@@ -34,7 +34,7 @@ def __init__(self, device):
             if not hasattr(var, 'visavariable'):
                 continue
             self.variables[var.pk] = var
-        
+
         if driver_visa_ok and driver_handler_ok:
             self._h.connect()
 
@@ -70,15 +70,16 @@ def request_data(self):
         if not driver_visa_ok:
             logger.info('Request Data Visa Driver Not Ok')
             return output
-        
+
+        self._h.before_read()
         for item in self.variables.values():
             if not item.visavariable.variable_type == 1:
                 # skip all config values
                 continue
-            
-            value = self._h.read_data(item)
-            
-            if value is not None and item.update_value(value, time()):
-                output.append(item.create_recorded_data_element())
 
+            value, time = self._h.read_data_and_time(item)
+
+            if value is not None and item.update_value(value, time):
+                output.append(item.create_recorded_data_element())
+        self._h.after_read()
         return output

pyscada/visa/devices/HP3456A.py

@@ -9,7 +9,7 @@ class Handler(GenericDevice):
     """
     HP3456A and other Devices with the same command set
     """
-    
+
     def read_data(self,variable_instance):
         """
         read values from the device
@@ -53,4 +53,4 @@ def parse_value(self,value):
         try:
             return float(value)
         except:
-            return None
+            return None

pyscada/visa/devices/__init__.py

@@ -4,13 +4,15 @@
 
 from django.conf import settings
 
-try: 
+try:
     import visa
     driver_ok = True
 except ImportError:
     visa = None
     driver_ok = False
 
+from time import time
+
 import logging
 
 logger = logging.getLogger(__name__)
@@ -60,15 +62,37 @@ def disconnect(self):
             return True
         return False
 
+    def before_read(self):
+        """
+        will be called before the first read_data
+        """
+        return None
+
+    def after_read(self):
+        """
+        will be called after the last read_data
+        """
+        return None
+
     def read_data(self, variable_instance):
         """
         read values from the device
         """
 
         return None
 
+    def read_data_and_time(self, variable_instance):
+        """
+        read values and timestamps from the device
+        """
+
+        return self.read_data(variable_instance), self.time()
+
     def write_data(self, variable_id, value, task):
         """
         write values to the device
         """
         return False
+
+    def time(self):
+        return time()