Alarm Condition

Condition objects define conditions that can raise alarms. They are used by Alarm_Rule s.

Each has to define a Condition.check() method that accepts SensorValues . The method should return True if the alarm condition is met, and False otherwise.

Conditions can be added (+) together to make compound conditions, and a single call to check will only return true if both conditions return true. If any condition in the chain returns false, evaluation is stopped and the alarm is not raised.

Conditions can

Classes:

AlarmSeverity(value)	An enumeration.
AlarmSeverityCondition(alarm_type, severity, …)	Alarm is above or below a certain severity.
AlarmType(value)	An enumeration.
Condition(depends, *args, **kwargs)	Base class for specifying alarm test conditions
CycleAlarmSeverityCondition(n_cycles, *args, …)	alarm goes out of range for a specific number of breath cycles
CycleValueCondition(n_cycles, *args, **kwargs)	Value goes out of range for a specific number of breath cycles
SensorValues([timestamp, loop_counter, …])	Structured class for communicating sensor readings throughout PVP.
TimeValueCondition(time, *args, **kwargs)	value goes out of range for specific amount of time
ValueCondition(value_name, limit, mode, …)	Value is greater or lesser than some max/min
ValueName(value)	Canonical names of all values used in PVP.

Functions:

get_alarm_manager()

pvp.alarm.condition.get_alarm_manager()

class pvp.alarm.condition.Condition(depends: dict = None, *args, **kwargs)

Bases: object

Base class for specifying alarm test conditions

Subclasses must define Condition.check() and Conditino.reset()

Condition objects can be added together to create compound conditions.

_child

if another condition is added to this one, store a reference to it

Type

Condition

Parameters

• depends (list, dict) –

  a list of, or a single dict:

  {'value_name':ValueName,
  'value_attr': attr in ControlMessage,
   'condition_attr',
   optional: transformation: callable)
  that declare what values are needed to update
  

• *args –

• **kwargs –

Methods:

__init__([depends])	param depends
check(sensor_values)	Every Condition subclass needs to define this method that accepts SensorValues and returns a boolean
reset()	If a condition is stateful, need to provide some method of resetting the state

Attributes:

manager

The active alarm manager, used to get status of alarms

__init__(depends: dict = None, *args, **kwargs)

Parameters

• depends (list, dict) –

  a list of, or a single dict:

  {'value_name':ValueName,
  'value_attr': attr in ControlMessage,
   'condition_attr',
   optional: transformation: callable)
  that declare what values are needed to update
  

• *args –

• **kwargs –

property manager

The active alarm manager, used to get status of alarms

Returns

pvp.alarm.alarm_manager.Alarm_Manager

check(sensor_values) → bool

Every Condition subclass needs to define this method that accepts SensorValues and returns a boolean

Parameters

sensor_values (SensorValues) – SensorValues used to compute alarm status

Returns

bool

reset()

If a condition is stateful, need to provide some method of resetting the state

class pvp.alarm.condition.ValueCondition(value_name: pvp.common.values.ValueName, limit: (<class 'int'>, <class 'float'>), mode: str, *args, **kwargs)

Bases: pvp.alarm.condition.Condition

Value is greater or lesser than some max/min

Parameters

• value_name (ValueName) – Which value to check

• limit (int, float) – value to check against

• mode ('min', 'max') – whether the limit is a minimum or maximum

• *args –

• **kwargs –

operator

Either the less than or greater than operators, depending on whether mode is 'min' or 'max'

Type

callable

Methods:

__init__(value_name, limit, mode, *args, …)	param value_name Which value to check
check(sensor_values)	Check that the relevant value in SensorValues is either greater or lesser than the limit
reset()	not stateful, do nothing.

Attributes:

mode	One of ‘min’ or ‘max’, defines how the incoming sensor values are compared to the set value

__init__(value_name: pvp.common.values.ValueName, limit: (<class 'int'>, <class 'float'>), mode: str, *args, **kwargs)

Parameters

• value_name (ValueName) – Which value to check

• limit (int, float) – value to check against

• mode ('min', 'max') – whether the limit is a minimum or maximum

• *args –

• **kwargs –

operator

Either the less than or greater than operators, depending on whether mode is 'min' or 'max'

Type

callable

property mode

One of ‘min’ or ‘max’, defines how the incoming sensor values are compared to the set value

Returns:

check(sensor_values)

Check that the relevant value in SensorValues is either greater or lesser than the limit

Parameters

sensor_values (SensorValues) –

Returns

bool

reset()

not stateful, do nothing.

class pvp.alarm.condition.CycleValueCondition(n_cycles: int, *args, **kwargs)

Bases: pvp.alarm.condition.ValueCondition

Value goes out of range for a specific number of breath cycles

Parameters

n_cycles (int) – number of cycles required

_start_cycle

The breath cycle where the

Type

int

_mid_check

whether a value has left the acceptable range and we are counting consecutive breath cycles

Type

bool

Parameters

• value_name (ValueName) – Which value to check

• limit (int, float) – value to check against

• mode ('min', 'max') – whether the limit is a minimum or maximum

• *args –

• **kwargs –

operator

Either the less than or greater than operators, depending on whether mode is 'min' or 'max'

Type

callable

Methods:

check(sensor_values)	Check if outside of range, and then check if number of breath cycles have elapsed
reset()	Reset check status and start cycle

Attributes:

n_cycles

Number of cycles required

property n_cycles

Number of cycles required

check(sensor_values) → bool

Check if outside of range, and then check if number of breath cycles have elapsed

Parameters

() (sensor_values) –

Returns

bool

reset()

Reset check status and start cycle

class pvp.alarm.condition.TimeValueCondition(time, *args, **kwargs)

Bases: pvp.alarm.condition.ValueCondition

value goes out of range for specific amount of time

Warning

Not implemented!

Parameters

• time (float) – number of seconds value must be out of range

• *args –

• **kwargs –

Methods:

__init__(time, *args, **kwargs)	param time number of seconds value must be out of range
check(sensor_values)	Check that the relevant value in SensorValues is either greater or lesser than the limit
reset()	not stateful, do nothing.

__init__(time, *args, **kwargs)

Parameters

• time (float) – number of seconds value must be out of range

• *args –

• **kwargs –

check(sensor_values)

Check that the relevant value in SensorValues is either greater or lesser than the limit

Parameters

sensor_values (SensorValues) –

Returns

bool

reset()

not stateful, do nothing.

class pvp.alarm.condition.AlarmSeverityCondition(alarm_type: pvp.alarm.AlarmType, severity: pvp.alarm.AlarmSeverity, mode: str = 'min', *args, **kwargs)

Bases: pvp.alarm.condition.Condition

Alarm is above or below a certain severity.

Get alarm severity status from Alarm_Manager.get_alarm_severity() .

Parameters

• alarm_type (AlarmType) – Alarm type to check

• severity (AlarmSeverity) – Alarm severity to check against

• mode (str) –

  one of ‘min’, ‘equals’, or ‘max’. ‘min’ returns true if the alarm is at least this value (note the difference from ValueCondition which returns true if the alarm is less than..) and vice versa for ‘max’.

  Note

  ’min’ and ‘max’ use >= and <= rather than > and <

• *args –

• **kwargs –

Methods:

__init__(alarm_type, severity[, mode])	Alarm is above or below a certain severity.
check(sensor_values)	Every Condition subclass needs to define this method that accepts SensorValues and returns a boolean
reset()	If a condition is stateful, need to provide some method of resetting the state

Attributes:

mode	‘min’ returns true if the alarm is at least this value (note the difference from ValueCondition which returns true if the alarm is less than..) and vice versa for ‘max’.

__init__(alarm_type: pvp.alarm.AlarmType, severity: pvp.alarm.AlarmSeverity, mode: str = 'min', *args, **kwargs)

Alarm is above or below a certain severity.

Get alarm severity status from Alarm_Manager.get_alarm_severity() .

Parameters

• alarm_type (AlarmType) – Alarm type to check

• severity (AlarmSeverity) – Alarm severity to check against

• mode (str) –

  one of ‘min’, ‘equals’, or ‘max’. ‘min’ returns true if the alarm is at least this value (note the difference from ValueCondition which returns true if the alarm is less than..) and vice versa for ‘max’.

  Note

  ’min’ and ‘max’ use >= and <= rather than > and <

• *args –

• **kwargs –

property mode

‘min’ returns true if the alarm is at least this value (note the difference from ValueCondition which returns true if the alarm is less than..) and vice versa for ‘max’.

Note

‘min’ and ‘max’ use >= and <= rather than > and <

Returns

one of ‘min’, ‘equals’, or ‘max’.

Return type

str

check(sensor_values)

Every Condition subclass needs to define this method that accepts SensorValues and returns a boolean

Parameters

sensor_values (SensorValues) – SensorValues used to compute alarm status

Returns

bool

reset()

If a condition is stateful, need to provide some method of resetting the state

class pvp.alarm.condition.CycleAlarmSeverityCondition(n_cycles, *args, **kwargs)

Bases: pvp.alarm.condition.AlarmSeverityCondition

alarm goes out of range for a specific number of breath cycles

Todo

note that this is exactly the same as CycleValueCondition. Need to do the multiple inheritance thing

_start_cycle

The breath cycle where the

Type

int

_mid_check

whether a value has left the acceptable range and we are counting consecutive breath cycles

Type

bool

Alarm is above or below a certain severity.

Get alarm severity status from Alarm_Manager.get_alarm_severity() .

Parameters

• alarm_type (AlarmType) – Alarm type to check

• severity (AlarmSeverity) – Alarm severity to check against

• mode (str) –

  one of ‘min’, ‘equals’, or ‘max’. ‘min’ returns true if the alarm is at least this value (note the difference from ValueCondition which returns true if the alarm is less than..) and vice versa for ‘max’.

  Note

  ’min’ and ‘max’ use >= and <= rather than > and <

• *args –

• **kwargs –

Methods:

check(sensor_values)	Every Condition subclass needs to define this method that accepts SensorValues and returns a boolean
reset()	If a condition is stateful, need to provide some method of resetting the state

Attributes:

n_cycles

property n_cycles

check(sensor_values)

Every Condition subclass needs to define this method that accepts SensorValues and returns a boolean

Parameters

sensor_values (SensorValues) – SensorValues used to compute alarm status

Returns

bool

reset()

If a condition is stateful, need to provide some method of resetting the state