diff --git a/pytac/device.py b/pytac/device.py
index 8181d3bc..631988e7 100644
--- a/pytac/device.py
+++ b/pytac/device.py
@@ -6,12 +6,7 @@
 magnets and a skew quadrupole.
 """
 import pytac
-
-
-class DeviceException(Exception):
-    """Exception associated with Device misconfiguration or invalid requests.
-    """
-    pass
+from pytac.exceptions import HandleException
 
 
 class Device(object):
@@ -70,10 +65,10 @@ def set_value(self, value):
             value (float): The value to set on the PV.
 
         Raises:
-            DeviceException: if no setpoint PV exists.
+            HandleException: if no setpoint PV exists.
         """
         if self.sp_pv is None:
-            raise DeviceException(
+            raise HandleException(
                 "Device {0} has no setpoint PV.".format(self.name)
             )
         self._cs.put(self.sp_pv, value)
@@ -89,7 +84,7 @@ def get_value(self, handle):
             float: The value of the PV.
 
         Raises:
-            DeviceException: if the requested PV doesn't exist.
+            HandleException: if the requested PV doesn't exist.
         """
         print('getting {}'.format('handle'))
         if handle == pytac.RB and self.rb_pv:
@@ -97,7 +92,7 @@ def get_value(self, handle):
         elif handle == pytac.SP and self.sp_pv:
             return self._cs.get(self.sp_pv)
 
-        raise DeviceException(
+        raise HandleException(
             "Device {0} has no {1} PV.".format(self.name, handle)
         )
 
@@ -111,14 +106,14 @@ def get_pv_name(self, handle):
             str: A readback or setpoint PV.
 
         Raises:
-            DeviceException: if the PV doesn't exist.
+            HandleException: if the PV doesn't exist.
         """
         if handle == pytac.RB and self.rb_pv:
             return self.rb_pv
         elif handle == pytac.SP and self.sp_pv:
             return self.sp_pv
 
-        raise DeviceException(
+        raise HandleException(
             "Device {0} has no {1} PV.".format(self.name, handle)
         )
 
diff --git a/pytac/element.py b/pytac/element.py
index 47401473..8b4342d9 100644
--- a/pytac/element.py
+++ b/pytac/element.py
@@ -1,6 +1,6 @@
 """Module containing the element class."""
 import pytac
-from pytac.device import DeviceException
+from pytac.exceptions import FieldException, HandleException, DeviceException
 
 
 class Element(object):
@@ -161,6 +161,7 @@ def get_value(self, field, handle=pytac.RB, units=pytac.ENG,
 
         Raises:
             DeviceException: if there is no device on the given field.
+            FieldException: if the element does not have the specified field.
         """
         try:
             model = self._models[model]
@@ -170,6 +171,8 @@ def get_value(self, field, handle=pytac.RB, units=pytac.ENG,
         except KeyError:
             raise DeviceException('No model type {} on element {}'.format(model,
                                                                           self))
+        except FieldException:
+            raise FieldException('No field {} on element {}'.format(field, self))
 
     def set_value(self, field, value, handle=pytac.SP, units=pytac.ENG,
                   model=pytac.LIVE):
@@ -187,16 +190,22 @@ def set_value(self, field, value, handle=pytac.SP, units=pytac.ENG,
 
         Raises:
             DeviceException: if arguments are incorrect.
+            FieldException: if the element does not have the specified field.
         """
         if handle != pytac.SP:
-            raise DeviceException('Must write using {}'.format(pytac.SP))
+            raise HandleException('Must write using {}'.format(pytac.SP))
         try:
             model = self._models[model]
-            value = self._uc[field].convert(value, origin=units, target=model.units)
-            model.set_value(field, value)
         except KeyError:
             raise DeviceException('No model type {} on element {}'.format(model,
                                                                           self))
+        try:
+            value = self._uc[field].convert(value, origin=units, target=model.units)
+            model.set_value(field, value)
+        except KeyError:
+            raise FieldException('No field {} on element {}'.format(model, self))
+        except FieldException:
+            raise FieldException('No field {} on element {}'.format(field, self))
 
     def get_pv_name(self, field, handle):
         """Get a PV name on a device.
@@ -210,9 +219,12 @@ def get_pv_name(self, field, handle):
 
         Raises:
             DeviceException: if there is no device for this field.
+            FieldException: if the element does not have the specified field.
         """
         try:
             return self._models[pytac.LIVE].get_pv_name(field, handle)
         except KeyError:
             raise DeviceException('{} has no device for field {}'.format(self,
                                                                          field))
+        except FieldException:
+            raise FieldException('No field {} on element {}'.format(field, self))
diff --git a/pytac/exceptions.py b/pytac/exceptions.py
new file mode 100644
index 00000000..60f67e8b
--- /dev/null
+++ b/pytac/exceptions.py
@@ -0,0 +1,29 @@
+"""Module containing all the exceptions used in pytac."""
+
+
+class FieldException(Exception):
+    """Exception associated with invalid field requests.
+    """
+    pass
+
+
+class HandleException(Exception):
+    """Exception associated with requests with invalid handles.
+    """
+    pass
+
+
+class DeviceException(Exception):
+    """Exception associated with Device misconfiguration or invalid requests.
+    """
+    pass
+
+
+class UnitsException(Exception):
+    """Conversion not understood
+    """
+    pass
+
+
+class LatticeException(Exception):
+    pass
diff --git a/pytac/lattice.py b/pytac/lattice.py
index 021e524b..f0585369 100644
--- a/pytac/lattice.py
+++ b/pytac/lattice.py
@@ -2,10 +2,7 @@
     machine.
 """
 import numpy
-
-
-class LatticeException(Exception):
-    pass
+from pytac.exceptions import LatticeException
 
 
 class Lattice(object):
diff --git a/pytac/model.py b/pytac/model.py
index 5b9f720f..475f433e 100644
--- a/pytac/model.py
+++ b/pytac/model.py
@@ -1,5 +1,6 @@
 """Module containing pytac model classes."""
 import pytac
+from pytac.exceptions import FieldException
 
 
 class Model(object):
@@ -116,8 +117,14 @@ def get_value(self, field, handle):
 
         Returns:
             float: The value of the PV.
+
+        Raises:
+            FieldException: if the device does not have the specified field.
         """
-        return self._devices[field].get_value(handle)
+        try:
+            return self._devices[field].get_value(handle)
+        except KeyError:
+            raise FieldException('No field {} on device {}'.format(field, self))
 
     def set_value(self, field, value):
         """Set the value of a readback or setpoint PV for a field from the
@@ -126,5 +133,11 @@ def set_value(self, field, value):
         Args:
             field (str): field for the requested value.
             value (float): The value to set on the PV.
+
+        Raises:
+            FieldException: if the device does not have the specified field.
         """
-        self._devices[field].set_value(value)
+        try:
+            self._devices[field].set_value(value)
+        except KeyError:
+            raise FieldException('No field {} on device {}'.format(field, self))
diff --git a/pytac/units.py b/pytac/units.py
index 6ce60ac5..a70e6f4c 100644
--- a/pytac/units.py
+++ b/pytac/units.py
@@ -1,15 +1,10 @@
 """Classes for use in unit conversion."""
 import pytac
 import numpy
+from pytac.exceptions import UnitsException
 from scipy.interpolate import PchipInterpolator
 
 
-class UnitsException(Exception):
-    """Conversion not understood
-    """
-    pass
-
-
 def unit_function(value):
     """Default value for the pre and post functions used in unit conversion.
 
diff --git a/test/test_device.py b/test/test_device.py
index a21335c7..8bfb3370 100644
--- a/test/test_device.py
+++ b/test/test_device.py
@@ -22,13 +22,13 @@ def test_set_device_value():
 
 def test_device_invalid_sp_raise_exception():
     device2 = create_device(PREFIX, RB_PV, None)
-    with pytest.raises(pytac.device.DeviceException):
+    with pytest.raises(pytac.exceptions.HandleException):
         device2.set_value(40)
 
 
 def test_get_device_value():
     device = create_device()
-    with pytest.raises(pytac.device.DeviceException):
+    with pytest.raises(pytac.exceptions.HandleException):
         device.get_value('non_existent')
 
 
diff --git a/test/test_element.py b/test/test_element.py
index 93b09dad..897d9eb8 100644
--- a/test/test_element.py
+++ b/test/test_element.py
@@ -106,16 +106,22 @@ def test_set_value_phys(test_element):
                                                             (DUMMY_VALUE_2 / 2))
 
 
-def test_set_value_incorrect_field(test_element):
-    with pytest.raises(pytac.device.DeviceException):
-        test_element.set_value('non_existent', 40.0)
-
-
-def test_get_pv_exceptions(test_element):
-    with pytest.raises(pytac.device.DeviceException):
-        test_element.get_value('setpoint', 'unknown_field')
-    with pytest.raises(pytac.device.DeviceException):
-        test_element.get_value('unknown_handle', 'y')
+def test_set_exceptions(test_element):
+    with pytest.raises(pytac.exceptions.FieldException):
+        test_element.set_value('unknown_field', 40.0, 'setpoint')
+    with pytest.raises(pytac.exceptions.HandleException):
+        test_element.set_value('y', 40.0, 'unknown_handle')
+    with pytest.raises(pytac.exceptions.DeviceException):
+        test_element.set_value('y', 40.0, 'setpoint', model='unknown_model')
+
+
+def test_get_exceptions(test_element):
+    with pytest.raises(pytac.exceptions.FieldException):
+        test_element.get_value('unknown_field', 'setpoint')
+    with pytest.raises(pytac.exceptions.HandleException):
+        test_element.get_value('y', 'unknown_handle')
+    with pytest.raises(pytac.exceptions.DeviceException):
+        test_element.get_value('y', 'setpoint', model='unknown_model')
 
 
 def test_identity_conversion():
diff --git a/test/test_lattice.py b/test/test_lattice.py
index 576fa9b1..950c97af 100644
--- a/test/test_lattice.py
+++ b/test/test_lattice.py
@@ -129,7 +129,7 @@ def test_set_values(simple_element_and_lattice):
 
 def test_set_values_raise_exception_if_number_of_values_does_not_match(simple_element_and_lattice):
     element, lattice = simple_element_and_lattice
-    with pytest.raises(pytac.lattice.LatticeException):
+    with pytest.raises(pytac.exceptions.LatticeException):
         lattice.set_values('family', 'x', [1, 2])
 
 
@@ -149,7 +149,7 @@ def test_s_position(simple_element_and_lattice):
 def test_get_s_throws_exception_if_element_not_in_lattice():
     lat = pytac.lattice.Lattice(LATTICE, mock.MagicMock(), 1)
     element = pytac.element.Element(1, 1.0, 'Quad')
-    with pytest.raises(pytac.lattice.LatticeException):
+    with pytest.raises(pytac.exceptions.LatticeException):
         lat.get_s(element)
 
 
diff --git a/test/test_machine.py b/test/test_machine.py
index 6cb40a7d..d37ecc3e 100644
--- a/test/test_machine.py
+++ b/test/test_machine.py
@@ -67,7 +67,7 @@ def test_load_bpms(ring_mode, n_bpms):
     for bpm in bpms:
         assert set(bpm.get_fields()) == bpm_fields
         assert re.match('SR.*BPM.*X', bpm.get_pv_name('x', pytac.RB))
-        with pytest.raises(pytac.device.DeviceException):
+        with pytest.raises(pytac.exceptions.HandleException):
             bpm.get_pv_name('x', pytac.SP)
     assert len(bpms) == n_bpms
     assert bpms[0].cell == 1
@@ -184,7 +184,7 @@ def test_quad_unitconv():
 
 def test_quad_unitconv_raise_exception():
     uc = pytac.units.PchipUnitConv([50.0, 100.0, 180.0], [-4.95, -9.85, -17.56])
-    with pytest.raises(pytac.units.UnitsException):
+    with pytest.raises(pytac.exceptions.UnitsException):
         uc.phys_to_eng(-0.7)
 
 
diff --git a/test/test_units.py b/test/test_units.py
index 35782ffd..9bad8a84 100644
--- a/test/test_units.py
+++ b/test/test_units.py
@@ -1,6 +1,7 @@
 import pytest
 import pytac
-from pytac.units import UnitConv, PolyUnitConv, PchipUnitConv, UnitsException
+from pytac.units import UnitConv, PolyUnitConv, PchipUnitConv
+from pytac.exceptions import UnitsException
 import numpy