Update and create control systems

Pipfile

@@ -17,3 +17,4 @@ pytest-lazy-fixture = "*"
 [packages]
 numpy = "*"
 scipy = "*"
+pyepics = "*"

pytac/__init__.py

@@ -12,9 +12,9 @@
 # Default argument flag.
 DEFAULT = 'default'
 
-from . import data_source, element, epics, exceptions, lattice, load_csv, units, utils  # noqa: E402
+from . import data_source, element, exceptions, lattice, load_csv, units, utils  # noqa: E402
 """Error 402 is suppressed as we cannot import these modules at the top of the
 file as the strings above must be set first or the imports will fail.
 """
-__all__ = ["data_source", "element", "epics", "exceptions", "lattice",
-           "load_csv", "units", "utils"]
+__all__ = ["data_source", "element", "exceptions", "lattice", "load_csv",
+           "units", "utils"]

pytac/caproto_cs.py

@@ -0,0 +1,128 @@
+import sys
+import logging
+import time as t
+from pytac.cs import ControlSystem
+from caproto.threading.client import Context, Batch
+if float(sys.version[:3]) < 3.3:  # TimoutError only exists in python >= 3.3.
+    from pytac.exceptions import TimeoutError  # Otherwise we define it manually
+
+
+class CaprotoControlSystem(ControlSystem):
+    """A control system using caproto to communicate with EPICS.
+
+    It is used to communicate over channel access with the hardware
+    in the ring.
+
+    **Methods:**
+    """
+    def __init__(self):
+        """Create a _results attribute so all methods can access it, and disable
+            logging to temporarily prevent caproto version response warnings
+            being incorrectly and excessively raised.
+        """
+        self._results = []
+        self.time = 0
+        logging.disable(logging.WARNING)  # Temporary.
+
+    def _append_result(self, response):
+        """Append a result to the current list of results.
+
+        Args:
+            response (caproto class): The response from epics containing the
+                                       result data.
+        """
+        self._results.append(response.data[0])
+
+    def get_single(self, pv):
+        """Get the value of a given PV.
+
+        Args:
+            pv (string): The process variable given as a string. It can be a
+                         readback or a setpoint PV.
+
+        Returns:
+            float: Represents the current value of the given PV.
+        """
+        pv_object = Context().get_pvs(pv)[0]
+        try:
+            return pv_object.read().data[0]
+        except TimeoutError:  # Only exists in python 3.3+ though caproto requires 3.6+
+            print('cannot connect to {}'.format(pv))
+            return None
+
+    def get_multiple(self, pvs):
+        """Get the value for given PVs.
+
+        Args:
+            pvs (list): A list of process variables, given as a strings. They
+                         can be a readback or setpoint PVs.
+
+        Returns:
+            list: of floats, representing the current values of the PVs.
+
+        Raises:
+            ValueError: if the PVs are not passed in as a list.
+        """
+        if not isinstance(pvs, list):
+            raise ValueError('Please enter PVs as a list.')
+        self._results = []
+        pv_objects = Context().get_pvs(*pvs)
+        with Batch() as b:
+            for pv_object in pv_objects:
+                try:
+                    self.time = t.time()
+                    while isinstance(pv_object.channel, type(None)):
+                        if (t.time() - self.time) > 1.0:
+                            raise TimeoutError
+                        else:
+                            pass  # Wait until pv object is fully initialised.
+                    b.read(pv_object, self._append_result)
+                except TimeoutError:
+                    self._results.append(None)
+                    print('cannot connect to {}'.format(pvs[pv_objects.index(pv_object)]))
+        while len(self._results) is not len(pvs):
+            pass  # Wait for results to be returned.
+        return self._results
+
+    def set_single(self, pv, value):
+        """Set the value of a given PV.
+
+        Args:
+            pv (string): The PV to set the value of. It must be a setpoint PV.
+            value (Number): The value to set the PV to.
+        """
+        pv_object = Context().get_pvs(pv)[0]
+        try:
+            pv_object.write(value, wait=False)
+        except TimeoutError:
+            print('cannot connect to {}'.format(pv))
+
+    def set_multiple(self, pvs, values):
+        """Set the values for given PVs.
+
+        Args:
+            pvs (list): A list of PVs to set the values of. It must be a
+                         setpoint PV.
+            values (list): A list of the numbers to set no the PVs.
+
+        Raises:
+            ValueError: if the PVs or values are not passed in as a list, or if
+                         the lists of values and PVs are diffent lengths.
+        """
+        if not isinstance(pvs, list) or not isinstance(values, list):
+            raise ValueError('Please enter PVs and values as a list.')
+        elif len(pvs) != len(values):
+            raise ValueError('Please enter the same number of values as PVs.')
+        pv_objects = Context().get_pvs(*pvs)
+        with Batch() as b:
+            for pv_object, value in zip(pv_objects, values):
+                try:
+                    self.time = t.time()
+                    while isinstance(pv_object.channel, type(None)):
+                        if (t.time() - self.time) > 1.0:
+                            raise TimeoutError
+                        else:
+                            pass  # Wait until pv object is fully initialised.
+                    b.write(pv_object, value)
+                except TimeoutError:
+                    print('cannot connect to {}'.format(pvs[pv_objects.index(pv_object)]))

pytac/cothread_cs.py

@@ -3,7 +3,8 @@
 
 
 class CothreadControlSystem(ControlSystem):
-    """ The EPICS control system.
+    """A control system using cothread to communicate with EPICS. N.B. this is
+        the default control system.
 
     It is used to communicate over channel access with the hardware
     in the ring.
@@ -13,8 +14,8 @@ class CothreadControlSystem(ControlSystem):
     def __init__(self):
         pass
 
-    def get(self, pv):
-        """ Get the value of a given PV.
+    def get_single(self, pv):
+        """Get the value of a given PV.
 
         Args:
             pv (string): The process variable given as a string. It can be a
@@ -23,13 +24,65 @@ def get(self, pv):
         Returns:
             float: Represents the current value of the given PV.
         """
-        return caget(pv)
+        try:
+            return float(caget(pv, timeout=1.0, throw=False))
+        except TypeError:
+            print('cannot connect to {}'.format(pv))
+            return None
 
-    def put(self, pv, value):
-        """ Set the value for a given.
+    def get_multiple(self, pvs):
+        """Get the value for given PVs.
+
+        Args:
+            pvs (list): A list of process variables, given as a strings. They
+                         can be a readback or setpoint PVs.
+
+        Returns:
+            list: of floats, representing the current values of the PVs.
+
+        Raises:
+            ValueError: if the PVs are not passed in as a list.
+        """
+        if not isinstance(pvs, list):
+            raise ValueError('Please enter PVs as a list.')
+        results = caget(pvs, timeout=1.0, throw=False)
+        for i in range(len(results)):
+            try:
+                results[i] = float(results[i])
+            except TypeError:
+                print('cannot connect to {}'.format(pvs[i]))
+                results[i] = None
+        return results
+
+    def set_single(self, pv, value):
+        """Set the value of a given PV.
 
         Args:
             pv (string): The PV to set the value of. It must be a setpoint PV.
             value (Number): The value to set the PV to.
         """
-        caput(pv, value)
+        try:
+            caput(pv, value, timeout=1.0, throw=True)
+        except Exception:
+            print('cannot connect to {}'.format(pv))
+
+    def set_multiple(self, pvs, values):
+        """Set the values for given PVs.
+
+        Args:
+            pvs (list): A list of PVs to set the values of. It must be a
+                         setpoint PV.
+            values (list): A list of the numbers to set no the PVs.
+
+        Raises:
+            ValueError: if the PVs or values are not passed in as a list, or if
+                         the lists of values and PVs are diffent lengths.
+        """
+        if not isinstance(pvs, list) or not isinstance(values, list):
+            raise ValueError('Please enter PVs and values as a list.')
+        elif len(pvs) != len(values):
+            raise ValueError('Please enter the same number of values as PVs.')
+        try:
+            caput(pvs, values, timeout=1.0, throw=True)
+        except Exception:
+            print('cannot connect to one or more PV(s).')

pytac/cs.py

@@ -2,26 +2,59 @@
 
 
 class ControlSystem(object):
-    """ Abstract base class representing a control system.
+    """Abstract base class representing a control system.
+
+    A specialised implementation of this class would be used to communicate over
+     channel access with the hardware in the ring.
 
     **Methods:**
     """
-    def get(self, pv):
-        """ Get the value of the given PV.
+    def get_single(self, pv):
+        """Get the value of a given PV.
 
         Args:
-            pv (string): The PV to get the value of.
+            pv (string): The process variable given as a string. It can be a
+                         readback or a setpoint PV.
 
         Returns:
-            Number: The numeric value of the PV.
+            float: Represents the current value of the given PV.
         """
         raise NotImplementedError()
 
-    def put(self, pv, value):
-        """ Put the value of a given PV.
+    def get_multiple(self, pvs):
+        """Get the value for given PVs.
 
         Args:
-            pv (string): The PV to put the value for.
-            value (Number): The value to be set.
+            pvs (list): A list of process variables, given as a strings. They
+                         can be a readback or setpoint PVs.
+
+        Returns:
+            list: of floats, representing the current values of the PVs.
+
+        Raises:
+            ValueError: if the PVs are not passed in as a list.
+        """
+        raise NotImplementedError()
+
+    def set_single(self, pv, value):
+        """Set the value of a given PV.
+
+        Args:
+            pv (string): The PV to set the value of. It must be a setpoint PV.
+            value (Number): The value to set the PV to.
+        """
+        raise NotImplementedError()
+
+    def set_multiple(self, pvs, values):
+        """Set the values for given PVs.
+
+        Args:
+            pvs (list): A list of PVs to set the values of. It must be a
+                         setpoint PV.
+            values (list): A list of the numbers to set no the PVs.
+
+        Raises:
+            ValueError: if the PVs or values are not passed in as a list, or if
+                         the lists of values and PVs are diffent lengths.
         """
         raise NotImplementedError()