Moving custom units out of powermeter class

pcdsdevices/custom_units.py

@@ -0,0 +1,7 @@
+import sympy.physics.units as units
+
+millijoule = mJ = units.quantities.Quantity("millijoule", abbrev='mJ')
+millijoule.set_global_relative_scale_factor(units.prefixes.milli, units.joule)
+
+microjoule = uJ = units.quantities.Quantity("microjoule", abbrev='uJ')
+microjoule.set_global_relative_scale_factor(units.prefixes.micro, units.joule)

pcdsdevices/pim.py

@@ -375,15 +375,6 @@ class PPMPowerMeter(BaseInterface, Device):
     `calibrated_mj` = (Signal - Background) / (Responsivity * Beam_Rate)
     """
     def __init__(self, prefix, *, name, **kwargs):
-        import sympy.physics.units as units
-        from sympy.physics.units.prefixes import micro, milli
-        from sympy.physics.units.quantities import Quantity
-        millijoule = mJ = Quantity("millijoule", abbrev='mJ')
-        millijoule.set_global_relative_scale_factor(milli, units.joule)
-        microjoule = uJ = Quantity("microjoule", abbrev='uJ')
-        microjoule.set_global_relative_scale_factor(micro, units.joule)
-        setattr(units, 'mJ', mJ)
-        setattr(units, 'uJ', uJ)
         super().__init__(prefix, name=name, **kwargs)
 
     tab_component_names = True

pcdsdevices/utils.py

@@ -22,6 +22,7 @@
 from ophyd.device import Device
 from ophyd.ophydobj import Kind
 
+from . import custom_units
 from ._html import collapse_list_head, collapse_list_tail
 from .type_hints import Number, OphydDataType
 
@@ -155,8 +156,15 @@ def convert_unit(value: float, unit: str, new_unit: str):
     new_value : float
         The starting value, but converted to the new unit.
     """
-    unit = getattr(units, unit)
-    new_unit = getattr(units, new_unit)
+    try:
+        unit = getattr(units, unit)
+    except Exception:
+        unit = getattr(custom_units, unit)
+
+    try:
+        new_unit = getattr(units, new_unit)
+    except Exception:
+        new_unit = getattr(custom_units, new_unit)
 
     if unit == new_unit:
         return value