TypeError: unsupported operand type(s) for -: 'float' and 'NoneType'` in cov.py

[villeilkkala]

I overwrite a presentValue of an analogValueObject in my COV application. I get the following error after a thousand or so overwrites:

Traceback (most recent call last): File "/usr/local/lib/python3.9/threading.py", line 973, in _bootstrap_inner self.run() File "/code/./main.py", line 230, in run bacnet_object.WriteProperty("presentValue", value) File "/usr/local/lib/python3.9/site-packages/bacpypes/object.py", line 620, in WriteProperty return prop.WriteProperty(self, value, arrayIndex, priority, direct) File "/usr/local/lib/python3.9/site-packages/bacpypes/object.py", line 363, in WriteProperty fn(old_value, value) File "/usr/local/lib/python3.9/site-packages/bacpypes/service/detect.py", line 45, in property_change trigger = self.filter(old_value, new_value) File "/usr/local/lib/python3.9/site-packages/bacpypes/service/cov.py", line 317, in present_value_filter value_changed = (new_value <= (self.previous_reported_value - self.obj.covIncrement)) \ TypeError: unsupported operand type(s) for -: 'float' and 'NoneType'

When I restart the service, a lot of messages come in in quick succession, so it happens almost immediately. The rate of overwrites slows down to 6 per minute after a while.

I don't see anything from the written values that would indicate anything:

Writing 6.43 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 5.31 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 2.89 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 7.14 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 3.94 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 3.18 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 0.07 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 8.87 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 4.87 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 1.87 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 1.78 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 7.13 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> Writing 4.85 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> unsupported operand type(s) for -: 'float' and 'NoneType' Writing 4.84 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> unsupported operand type(s) for -: 'float' and 'NoneType' Writing 7.27 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> unsupported operand type(s) for -: 'float' and 'NoneType' Writing 4.75 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> unsupported operand type(s) for -: 'float' and 'NoneType' Writing 6.3 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> unsupported operand type(s) for -: 'float' and 'NoneType' Writing 3.56 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> unsupported operand type(s) for -: 'float' and 'NoneType' Writing 6.95 to <main.WritableAnalogValueObject object at 0x7f41eadc3130> unsupported operand type(s) for -: 'float' and 'NoneType' Writing 6.94 to <main.WritableAnalogValueObject object at 0x7f41eadc3130>

This has been tested with covIncrement=1.0 and without specifying one.

[villeilkkala]

The error seems to disappear when I set the covIncrement to such a low value, that the notification is always triggered.

[JoelBender]

It would seem there is some tracking of what was previously reported that is getting cleared. Is this code using threads? I'm going to try and reproduce this error.

[villeilkkala]

Yes, this is running in a separate thread.