diff --git a/kamzik3/devices/attribute.py b/kamzik3/devices/attribute.py
index b10d9d0b381e3c71a8c80f1081131f264c8ce30a..ad27a63f39eb89e3f34f9600966832d004d50d31 100755
--- a/kamzik3/devices/attribute.py
+++ b/kamzik3/devices/attribute.py
@@ -491,7 +491,7 @@ class Attribute(dict):
         else:
             return [attribute]
 
-    def convert_units(self, value: Optional[Quantity]):
+    def convert_units(self, value: Quantity):
         """
         Convert input value to current attribute unit.
 
@@ -507,7 +507,7 @@ class Attribute(dict):
 
         return value.to(self[UNIT])
 
-    def within_limits(self, value: Optional[Quantity]) -> bool:
+    def within_limits(self, value: Quantity) -> bool:
         """
         Check if value is within limits.
 
@@ -519,7 +519,7 @@ class Attribute(dict):
         assert isinstance(value, Quantity)
         return bool(self.minimum() <= value <= self.maximum())
 
-    def within_tolerance(self, value: Optional[Quantity]) -> bool:
+    def within_tolerance(self, value: Quantity) -> bool:
         """
         Check if value is within tolerance.
 
@@ -528,6 +528,8 @@ class Attribute(dict):
         """
         assert isinstance(value, Quantity)
         setpoint = self.setpoint()
+        if setpoint is None:
+            setpoint = self.value()
         return bool(
             (setpoint - self.negative_tolerance())
             <= value
diff --git a/kamzik3/devices/deviceTango.py b/kamzik3/devices/deviceTango.py
index 34bc3bfa91012df35fb4c4d29e74c731b3d9bfd6..276fc2f4a6d4dc0b09db7e700b385618b558c4da 100755
--- a/kamzik3/devices/deviceTango.py
+++ b/kamzik3/devices/deviceTango.py
@@ -6,7 +6,7 @@ from threading import Thread
 
 import numpy as np
 
-from kamzik3 import DeviceError
+from kamzik3 import DeviceError, units
 from kamzik3.constants import *
 from kamzik3.devices.device import Device
 from kamzik3.snippets.snippetsDecorators import expose_method
@@ -147,6 +147,25 @@ class DeviceTango(Device, DeviceProxy):
             else:
                 value = str(value)
 
+            try:
+                if tc.unit is None:
+                    unit = ""  # "" raises an AttributeError in pint
+                elif tc.unit == "%":
+                    unit = tc.unit  # "%" raises an AttributeError in pint
+                elif tc.unit != "" and tc.unit not in units:
+                    self.logger.info(
+                        f"{self.device_id}: not a valid unit '{tc.unit}', "
+                        "default unit to ''"
+                    )
+                    unit = ""
+                else:
+                    unit = tc.unit
+            except (ValueError, TypeError):  # issue with parsing in pint
+                self.logger.error(
+                    f"{self.device_id}: can't parse {tc.unit}, default unit to ''"
+                )
+                unit = ""
+
             self.create_attribute(
                 attribute,
                 default_value=value,
@@ -154,7 +173,7 @@ class DeviceTango(Device, DeviceProxy):
                 description=tc.description,
                 default_type=default_type,
                 set_function=set_function,
-                unit=tc.unit,
+                unit=unit,
                 min_value=min_value,
                 max_value=max_value,
                 decimals=decimals,
@@ -475,14 +494,14 @@ class DeviceTangoEigerDetector(DeviceTango):
 
         :param Exposure: desired exposure time per frame
         """
-        self.logger.info(f"Live view has started.")
+        self.logger.info("Live view has started.")
         self.set_attribute(["TriggerMode", VALUE], 3)
         if self.file_writer is not None:
-            self.logger.info(f"FileWriter disabled")
+            self.logger.info("FileWriter disabled")
             self.set_attribute(["FileWriter", "Mode", VALUE], 1)
             self.set_attribute(["FileWriter", "NimagesPerFile", VALUE], 1000000)
         if self.eiger_stream is not None:
-            self.logger.info(f"EigerStream disabled")
+            self.logger.info("EigerStream disabled")
             self.set_attribute(["EigerStream", "Mode", VALUE], 1)
         Exposure = float(device_units(self, "FrameTime", Exposure).m)
         # According to Jan 10ms is lowest frame time