PIconnect documentation

A python connector to the OSISoft PI and PI-AF databases

This connector allows access to the OSISoft PI System through their proprietary SDK. It provides a number of classes, mostly mirroring the AF SDK structure, but at the same time implementing the cool stuff we use Python for.

The documentation for PIconnect is roughly structured according to Daniele Procida’s proposed structure:

  • The basic introductions to using PIconnect are covered in the Tutorials.

  • The technical reference to all modules within PIconnect are covered in API Reference. These also include several links to the original SDK documentation for important implementation details.

  • Background explanations and how-to guides still need to be written.

Contents

Installation

Stable release

To install PIconnect, run this command in your terminal:

$ pip install PIconnect

This is the preferred method to install PIconnect, as it will always install the most recent stable release.

If you don’t have pip installed, this Python installation guide can guide you through the process.

From sources

The sources for PIconnect can be downloaded from the Github repo.

You can either clone the public repository:

$ git clone git://github.com/Hugovdberg/PIconnect

Or download the tarball:

$ curl  -OL https://github.com/Hugovdberg/PIconnect/tarball/master

Once you have a copy of the source, you can install it with:

$ python setup.py install

Tutorials

To start using the PIconnect package a number of short tutorials are available. It is recommended to start with the Basics tutorials, which cover the connections to the different PI Systems.

Basics

Connecting to a PI Server

To connect to a PI Server you need to use the PIServer class. The following code connects to the default database and prints its name.:

import PIconnect as PI

with PI.PIServer() as server:
    print(server.server_name)

The next step is to get a list of PIPoint objects from the server, and print the first ten of those:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')
    for point in points[:10]:
        print(point)

To get the data as stored in the archive for a given point, we can use the PIPoint.recorded_values method. The following snippet gets the data recorded in the last 48 hours:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')
    data = points[0].recorded_values('*-48h', '*')
    print(data)

The resulting data object is essentially a decorated version of a pandas.Series, and can be used for any further processing.

Connecting to other servers

By default PIServer connects to the default server, as reported by the SDK. To find out which other servers are available you can use the servers dictionary. The keys to the dictionary are the server names. You can get the list of server names like this:

import PIconnect as PI
print(list(PI.PIServer.servers.keys()))

To explicitly connect to any of the available servers, you pass the name of the server to the PIServer constructor.

import PIconnect as PI

with PI.PIServer(server='ServerName') as server:
    print(server.server_name)

Note

When the server name is not found in the dictionary, a warning is raised and a connection to the default server is returned instead.

Connecting to a PI AF Database

To retrieve data from the PI Asset Framework, the PIAFDatabase object should be used. The following code connects to the default database on the default server, and prints its server name:

import PIconnect as PI

with PI.PIAFDatabase() as database:
    print(database.server_name)

The Asset Framework represents a hierarchy of elements, with attributes on the elements. The database has a dictionary of children, which you can loop over as follows:

import PIconnect as PI

with PI.PIAFDatabase() as database:
    for root in database.children.values():
        print("Root element: {r}".format(r=root))

The keys of the dictionary are the names of the elements inside. The following snippet first gets the first key in the dictionary, and the uses that to get the corresponding PIAFElement from the dictionary. Then from this element its PIAFAttribute are extracted:

import PIconnect as PI

with PI.PIAFDatabase() as database:
    key = next(iter(database.children))
    element = database.children[key]
    for attr in element.attributes:
        print(element.attributes[attr])

To get the data for the last 48 hours from a given attribute you need the PIAFAttribute.recorded_values method:

import PIconnect as PI

with PI.PIAFDatabase() as database:
    key = next(iter(database.children))
    element = database.children[key]
    attribute = next(iter(element.attributes.values()))
    data = attribute.recorded_values("*-48h", "*")
    print(data)

Note

Attributes on root elements within the database might not have meaningful summaries. To get a better result take a look at Finding descendants in the hierarchy below.

Finding descendants in the hierarchy

Whilst it is possible to traverse the hierarchy one at a time, by using the PIAFElement.children dictionaries, it is also possible to get a further descendant using the PIAFElement.descendant method. Assuming the database has a root element called Plant1 with a child element Outlet, the latter element could be accessed directly as follows:

import PIconnect as PI

with PI.PIAFDatabase() as database:
    element = database.descendant(r"Plant1\Outlet")

Note

Elements in the hierarchy are separated by a single backslash \, use either raw strings (using the r prefix, as in the example above) or escape each backslash as \\\\.

Connecting to other servers or databases

When no arguments are passed to the PIAFDatabase constructor, a connection is returned to the default database on the default server. It is possible to connect to other servers or databases, by passing the name of the server and database as arguments to the PIAFDatabase constructor.

import PIconnect as PI

with PI.PIAFDatabase(server="ServerName", database="DatabaseName") as database:
    print(database.server_name)

Note

It is also possible to specify only server or database. When only server is specified, a connection to the default database on that server is returned. Similarly, when only a database is specified, the connection is made to that database on the default server.

A list of the available servers can be found in the PIAFDatabase.servers attribute. This is a dictionary, where the keys are the server names. To get the list of server names you can use the following code.

import PIconnect as PI
print(list(PI.PIAFDatabase.servers.keys()))

A list of the databases on a given server can be retrieved from the same PIAFDatabase.servers attribute. Each item in the dictionary of servers is a dictionary with two items, server and databases. The first contains the raw server object from the SDK, while the databases item is a dictionary of {name: object} pairs. So to get the databases for a given server you can use the following code:

import PIconnect as PI
print(list(PI.PIAFDatabase.servers["ServerName"]["databases"].keys()))

Data extraction

Extracting recorded values

The data in the PI archives are typically compressed 1. To get the exact values as they are stored in the archive, the recorded_values method should be used. It is also possible to extract a single historic value using recorded_value. This is available on both PIPoint, and PIAFAttribute objects.

For simplicity this tutorial only uses PIPoint objects, see the tutorial on PI AF to find how to access PIAFAttribute objects.

1

More information on the compression algorithm can be found in this youtube video: OSIsoft: Exception and Compression Full Details.

Single vs Multiple values

We start of by extracting a the value from the first PIPoint that is returned by the server as it was 5 minutes ago.

import PIconnect as PI

with PI.PIServer() as server:
    point = server.search('*')[0]
    data = point.recorded_value('-5m')
    print(data)

You will see PISeries is printed containing a single row, with the PIPoint name as the Series name, the point value as the value, and the corresponding timestamp as the index.

By default the PI Server automatically detects which value to select and returns it with the requested timestamp as the index. To control which value is returned, we pass the retrieval_mode argument to recorded_value:

import PIconnect as PI
from PIconnect.PIConsts import RetrievalMode

with PI.PIServer() as server:
    point = server.search('*')[0]
    data = point.recorded_value('-5m', retrieval_mode=RetrievalMode.AT_OR_BEFORE)
    print(data)

Since it is unlikely there is a value at exactly 5 minutes ago, the PI Server now returns the latest value that’s before the requested time. Also the index is now no longer at the requested time, but at the time the value was recorded.

Now to get a time series of the values from the PIPoint we use the recorded_values method, and pass a start_time and end_time:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.recorded_values('*-48h', '*')
    print(data)
Boundary types

By default only the data between the start_time and end_time is returned. It is also possible to instead return the data from the last value before start_time up to and including the first value after end_time, by setting the boundary_type to outside:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.recorded_values('*-48h', '*', boundary_type='outside')
    print(data)

Warning

The boundary_type argument currently takes a string as the key to the internal __boundary_types dictionary. This will change in a future version to an enumeration in PIConsts.

Finally, it is also possible to interpolate the values surrounding both boundaries such that a value is returned exactly at the requested timestamp:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.recorded_values('*-48h', '*', boundary_type='interpolate')
    print(data)
Filtering values

Sometimes it is desirable to exclude certain values from the returned data. This is possible using the filter_expression argument of the PIPoint.recorded_values method. Only values matching the expression are returned.

The simplest test is to only return values below a given value. To test if the values of a tag called Plant1_Flow_out are below the value 100, you need the filter_expression=“‘Plant1_Flow_out’ < 100”. PIPoint.recorded_values provides a shortcut to include the tag name, by replacing %tag% with the current tag name:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')[0]
    print(points.recorded_values(
        '*-48h',
        '*',
         filter_expression="'%tag%' < 115"
    ))

Multiple tests can be combined with the keywords and and or:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')[0]
    print(points.recorded_values(
        '*-48h',
        '*',
         filter_expression="'%tag%' > 100 and '%tag%' < 115"
    ))
Extracting interpolated values

Since the data in the PI archive is compressed by default, the time interval between consecutive values is typically irregular. To get values at regular intervals the interpolated_values method is used. This is available on both PIPoint, and PIAFAttribute objects.

For simplicity this tutorial only uses PIPoint objects, see the tutorial on PI AF to find how to access PIAFAttribute objects.

Basic usage

The basic example takes the first PIPoint that is returned by the server and gets the data for the last hour at 5 minute intervals, by specifying the start_time, end_time, and interval arguments to PIPoint.interpolated_values:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.interpolated_values('*-1h', '*', '5m')
    print(data)
Filtering values

To filter the interpolated values the same filter_expression syntax as for Filtering values can be used.

Extracting summaries
Extracting a summary for a single time interval

The PI system allows multiple types of summaries to be calculated from data. To get the maximum value of a PIPoint in the last 14 days, you would use the PIPoint.summary method. This takes at least three arguments, start_time, end_time and summary_types, as shown in the following code:

import PIconnect as PI
from PIconnect.PIConsts import SummaryType

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.summary('*-14d', '*', SummaryType.MAXIMUM)
    print(data)

The returned data is a pandas.DataFrame with the timestamps as index and a column for each requested summary. The timestamp in this case is the datetime at which the maximum occurred. This is more obvious when requesting multiple summaries over the same time span:

import PIconnect as PI
from PIconnect.PIConsts import SummaryType

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.summary('*-14d', '*', SummaryType.MAXIMUM | SummaryType.MINIMUM)
    print(data)

Similarly, a PIAFAttribute also has a PIAFAttribute.summary method, that works in the same way:

import PIconnect as PI
from PIconnect.PIConsts import SummaryType

with PI.PIAFDatabase() as database:
    key = next(iter(database.children))
    element = database.children[key]
    attribute = next(iter(element.attributes.values()))
    data = attribute.summary('*-14d', '*', SummaryType.MAXIMUM | SummaryType.MINIMUM)
    print(data)

Note

Attributes on root elements within the database might not have meaningful summaries. To get a better result take a look at Finding descendants in the hierarchy.

Summary timestamps

Since the minimum and maximum of a point never occur at the same timestamp, the DataFrame in the previous example will typically occur two row. It is possible to reduce that to a single timestamp, when the time at which the summary value occurs is of no value.

There are two possibilities for the timestamp, the beginning of the requested time interval, or the end of the interval. Which to return is specified using the time_type argument. To always return the beginning of the interval, you should use the TimestampCalculation.EARLIEST_TIME constant from PIConsts:

import PIconnect as PI
from PIconnect.PIConsts import SummaryType, TimestampCalculation

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.summary(
        '*-14d',
        '*',
        SummaryType.MAXIMUM | SummaryType.MINIMUM,
        time_type=TimestampCalculation.EARLIEST_TIME
    )
    print(data)

Similarly, the TimestampCalculation.MOST_RECENT_TIME constant always returns the time at the end of the interval:

import PIconnect as PI
from PIconnect.PIConsts import SummaryType, TimestampCalculation

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.summary(
        '*-14d',
        '*',
        SummaryType.MAXIMUM | SummaryType.MINIMUM,
        time_type=TimestampCalculation.MOST_RECENT_TIME
    )
    print(data)
Event weighting

Summaries of multiple data points, or events, in time can be calculated in several ways. By default each event is weighted according to the period of time for which it is valid. This period depends on the type of data, whether it is stepped or continuous data.

To get an unweighted summary, in which every event has equal weight, the CalculationBasis.EVENT_WEIGHTED constant from the PIConsts module should be used:

import PIconnect as PI
from PIconnect.PIConsts import CalculationBasis, SummaryType

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.summary(
        '*-14d',
        '*',
        SummaryType.MAXIMUM | SummaryType.MINIMUM,
        calculation_basis=CalculationBasis.EVENT_WEIGHTED
    )
    print(data)
Extracting summaries at regular time intervals

Besides extracting a single summary over an entire period of time, it is also possible to extract summaries at fixed intervals within a period of time. This is done using the PIPoint.summaries or PIAFAttribute.summaries methods. In addition to the singular summary() method, this takes an interval as an argument. The following code extracts the maximum value for each hour within the last 14 days:

import PIconnect as PI
from PIconnect.PIConsts import SummaryType

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.summaries('*-14d', '*', '1h', SummaryType.MAXIMUM)
    print(data)

Just as the summary() methods, the summaries() methods support both changing the Event weighting and Summary timestamps.

Configuring timezones

Warning

Default timezone changed from Europe/Amsterdam to UTC in 0.8.0

By default the data is extracted in the UTC timezone. This is done since no fool proof way is available to detect the local timezone. It is however possible to configure the timezone used by PIconnect. This is done using the PIConfig.DEFAULT_TIMEZONE option. It takes any valid pytz timezone name, such as Europe/Amsterdam or America/Sao_Paulo.

import PIconnect as PI

print(PI.PIConfig.DEFAULT_TIMEZONE)
with PI.PIServer() as server:
    points = server.search('*')
    data = points[0].recorded_values('-1h', '*')

print(data.index.tz)

PI.PIConfig.DEFAULT_TIMEZONE = 'Etc/GMT-1'

with PI.PIServer() as server:
    points = server.search('*')
    data = points[0].recorded_values('-1h', '*')

print(data.index.tz)

The output is always a pandas.Series object with a timezone aware pandas.DatetimeIndex, so it is also possible to convert the timezone afterwards like:

data.index = data.index.tz_convert('Europe/Amsterdam')
Extracting event frames

Since the data in the PI archive is compressed by default, the time interval between consecutive values is typically irregular. To get values at regular intervals the interpolated_values method is used. This is available on both PIPoint, and PIAFAttribute objects.

For simplicity this tutorial only uses PIPoint objects, see the tutorial on PI AF to find how to access PIAFAttribute objects.

Basic usage

The basic example takes the first PIPoint that is returned by the server and gets the data for the last hour at 5 minute intervals, by specifying the start_time, end_time, and interval arguments to PIPoint.interpolated_values:

import PIconnect as PI

with PI.PIServer() as server:
    points = server.search('*')[0]
    data = points.interpolated_values('*-1h', '*', '5m')
    print(data)
Filtering values

To filter the interpolated values the same filter_expression syntax as for Filtering values can be used.

Data manipulation

Update value in PI

Writing a value back to PI using Python is a interesting feature. Having this capability we can use PIconnect for implementing collecting data process it someway (e.g. a prediction model) and write back the results someway it can be used by final users

After discussion with @Hugovdberg & with contribution of @ldariva we finally implemented an interface for the AFSDK UpdateValue method with 4 parameters value as AFValue time as python datetime.datetime with specified timezone replace_option as AFUpdateOption buffer_option as AFBufferOption.

from datetime import datetime
import pytz
import PIconnect as PI
from PIconnect.PIConsts import UpdateMode, BufferMode
tag = 'foo'
with PI.PIServer(server='foo') as server:
    point = server.search(tag)[0]
    point.update_value(1.0, datetime.now(pytz.utc), UpdateMode.NO_REPLACE, BufferMode.BUFFER_IF_POSSIBLE)

API Reference

PIconnect Connector to the OSISoft PI and PI-AF databases.

Generic utility modules

PIconnect.AFSDK module

AFSDK Loads the .NET libraries from the OSIsoft AF SDK

class PIconnect.AFSDK.AF

Bases: object

Mock class of the AF namespace

class AFDatabase(name)

Bases: object

Mock class of the AF.AFDatabase class

class AFElement(name)

Bases: object

Mock class of the AF.AFElement class

class Data

Bases: object

Mock class of the AF.Data namespace

class AFBoundaryType(value)

Bases: enum.IntEnum

Mock class of the AF.Data.AFBoundaryType enumeration

Inside = 0
Interpolated = 2
Outside = 1
class PI

Bases: object

Mock class of the AF.PI namespace

class PIPoint

Bases: object

Mock class of the AF.PI.PIPoint class

static FindPIPoints(connection, query, source, attribute_names)

Stub to mock querying PIPoints

class PIServer(name)

Bases: object

Mock class of the AF.PI.PIServer class

Connect(retry)

Stub for connecting to test server

Disconnect()

Stub for disconnecting from test server

class PIServers

Bases: object

Mock class of the AF.PI.PIServers class

DefaultPIServer = None
class PISystem(name)

Bases: object

Mock class of the AF.PISystem class

Connect()

Stub to connect to the testing system

Disconnect()

Stub to disconnect from the testing system

class InternalDatabases

Bases: object

Mock class for the AF.PISystem.Databases property

class PISystems

Bases: object

Mock class of the AF.PISystems class

DefaultPISystem = None
Version = '0.0.0.0'
class Time

Bases: object

Mock class of the AF.Time namespace

class AFTimeRange(start_time, end_time)

Bases: object

Mock class of the AF.Time.AFTimeRange class

class AFTimeSpan

Bases: object

Mock class of the AF.Time.AFTimeSpan class

static Parse(interval)

Stub for parsing strings that should return a AFTimeSpan

PIconnect.PIConsts module
class PIconnect.PIConsts.AuthenticationMode(value)

Bases: enum.IntEnum

AuthenticationMode indicates how a user authenticates to a PI Server

Detailed information is available at AF.PI.PIAuthenticationMode.

PI_USER_AUTHENTICATION = 1

Use the PI User authentication mode when making a connection

WINDOWS_AUTHENTICATION = 0

Use Windows authentication when making a connection

class PIconnect.PIConsts.BufferMode(value)

Bases: enum.IntEnum

Indicates buffering option in updating values, when supported by the Data Reference.

Detailed information is available at AF.Data.AFBufferOption

BUFFER = 2
BUFFER_IF_POSSIBLE = 1

Try updating data reference values with buffer. If fails (e.g. data reference AFDataMethods does not support Buffering, or its Buffering system is not available), then try updating directly without buffer.

DO_NOT_BUFFER = 0

Updating data reference values without buffer.

class PIconnect.PIConsts.CalculationBasis(value)

Bases: enum.IntEnum

CalculationBasis indicates how values should be weighted over a time range

Detailed information is available at AF.Data.AFCalculationBasis.

EVENT_WEIGHTED = 1

Each event is weighted equally.

EVENT_WEIGHTED_EXCLUDE_EARLIEST = 5

Each event is weighted equally, except data at the beginning of the interval is excluded.

EVENT_WEIGHTED_EXCLUDE_MOST_RECENT = 4

Each event is weighted equally, except data at the end of the interval is excluded.

EVENT_WEIGHTED_INCLUDE_BOTH_ENDS = 6

Each event is weighted equally, data at both boundaries of the interval are explicitly included.

TIME_WEIGHTED = 0

Each event is weighted according to the time over which it applies.

TIME_WEIGHTED_CONTINUOUS = 2

Each event is time weighted, but interpolation is always done as if it is continous data.

TIME_WEIGHTED_DISCRETE = 3

Each event is time weighted, but interpolation is always done as if it is discrete, stepped, data.

class PIconnect.PIConsts.EventFrameSearchMode(value)

Bases: enum.IntEnum

EventFrameSearchMode defines the interpretation and direction from the start time when searching for event frames.

Detailed information is available at https://techsupport.osisoft.com/Documentation/PI-AF-SDK/html/T_OSIsoft_AF_EventFrame_AFEventFrameSearchMode.htm, including a graphical display of event frames that are returned for a given search mode.

BACKWARD_FROM_END_TIME = 3

Backward from end time, also known as ending before

BACKWARD_FROM_START_TIME = 1

Backward from start time, also known as starting before

BACKWARD_IN_PROGRESS = 5

Backward in progress, also known as starting before and in progress

ENDING_AFTER = 4
ENDING_BEFORE = 3
FORWARD_FROM_END_TIME = 4

Forward from end time, also known as ending after

FORWARD_FROM_START_TIME = 2

Forward from start time, also known as starting after

FORWARD_IN_PROGRESS = 6

Forward in progress, also known as starting after and in progress

NONE = 0

Uninitialized

STARTING_AFTER = 2
STARTING_AFTER_IN_PROGRESS = 6
STARTING_BEFORE = 1
STARTING_BEFORE_IN_PROGRESS = 5
class PIconnect.PIConsts.ExpressionSampleType(value)

Bases: enum.IntEnum

ExpressionSampleType indicates how expressions are evaluated over a time range.

Detailed information is available at AF.Data.AFSampleType.

EXPRESSION_RECORDED_VALUES = 0

The expression is evaluated at each archive event.

INTERVAL = 1

The expression is evaluated at a sampling interval, passed as a separate argument.

class PIconnect.PIConsts.RetrievalMode(value)

Bases: enum.IntEnum

RetrievalMode indicates which recorded value should be returned

Detailed information is available at AF.Data.AFRetrievalMode.

AFTER = 7

The first after the requested time

AT_OR_AFTER = 2

At the exact time if available, else the first after the requested time

AT_OR_BEFORE = 1

At the exact time if available, else the first before the requested time

AUTO = 0

Autmatic detection

BEFORE = 6

The first before the requested time

EXACT = 4

At the exact time if available, else return an error

class PIconnect.PIConsts.SummaryType(value)

Bases: enum.IntFlag

SummaryType indicates which types of summary should be calculated.

Based on enum.IntEnum in Python 3.5 or earlier. SummaryType’s can be or’ed together. Python 3.6 or higher returns a new IntFlag, while in previous versions it will be casted down to int.

>>> SummaryType.MINIMUM | SummaryType.MAXIMUM  # Returns minimum and maximum
<SummaryType.MAXIMUM|MINIMUM: 12>  # On Python 3.6+
12  # On previous versions

Detailed information is available at AF.Data.AFSummaryTypes.

ALL = 24831

A convenience to retrieve all summary types

ALL_FOR_NON_NUMERIC = 8320

A convenience to retrieve all summary types for non-numeric data

AVERAGE = 2

Average value over the time span

COUNT = 128

The sum of the event count (when the calculation is event weighted). The sum of the event time duration (when the calculation is time weighted.)

MAXIMUM = 8

The maximum value in the time span

MINIMUM = 4

The minimum value in the time span

NONE = 0

No summary data

PERCENT_GOOD = 8192

The percentage of the data with a good value over the time range. Based on time for time weighted calculations, based on event count for event weigthed calculations.

POP_STD_DEV = 64

The population standard deviation of the values over the time span

RANGE = 16

The range of the values (max-min) in the time span

STD_DEV = 32

The sample standard deviation of the values over the time span

TOTAL = 1

A total over the time span

TOTAL_WITH_UOM = 16384

The total over the time span, with the unit of measurement that’s associated with the input (or no units if not defined for the input).

class PIconnect.PIConsts.TimestampCalculation(value)

Bases: enum.IntEnum

TimestampCalculation defines the timestamp returned for a given summary calculation

Detailed information is available at AF.Data.AFTimeStampCalculation.

AUTO = 0

The timestamp is the event time of the minimum or maximum for those summaries or the beginning of the interval otherwise.

EARLIEST_TIME = 1

The timestamp is always the beginning of the interval.

MOST_RECENT_TIME = 2

The timestamp is always the end of the interval.

class PIconnect.PIConsts.UpdateMode(value)

Bases: enum.IntEnum

Indicates how to treat duplicate values in the archive, when supported by the Data Reference.

Detailed information is available at AF.Data.AFUpdateOption

INSERT = 1

Add the value to the archive. Any existing values at the same time are not overwritten.

INSERT_NO_COMPRESSION = 5

Add the value to the archive without compression. If this value is written to the snapshot, the previous snapshot value will be written to the archive, without regard to compression settings. Note that if a subsequent snapshot value is written without the InsertNoCompression option, the value added with the InsertNoCompression option is still subject to compression.

NO_REPLACE = 2

Add the value to the archive only if no value exists at the same time. If a value already exists for that time, the passed value is ignored.

REMOVE = 6

Remove the value from the archive if a value exists at the passed time.

REPLACE = 0

Add the value to the archive. If any values exist at the same time, will overwrite one of them and set its Substituted flag.

REPLACE_ONLY = 3

Replace an existing value in the archive at the specified time. If no existing value is found, the passed value is ignored.

PIconnect.PIConsts.get_enumerated_value(enumeration, value, default)
PIconnect.PIData module

PIData contains a number of auxiliary classes that define common functionality among PIPoint and PIAFAttribute objects.

class PIconnect.PIData.PISeriesContainer

Bases: abc.ABC

With the ABC class we represent a general behaviour with PI Point object (General class for objects that return PISeries objects).

Todo

Move __boundary_types to PIConsts as a new enumeration

property current_value

Return the current value of the attribute.

filtered_summaries(start_time, end_time, interval, filter_expression, summary_types, calculation_basis=None, filter_evaluation=None, filter_interval=None, time_type=None)

Return one or more summary values for each interval within a time range

Parameters

  • start_time (str or datetime) – String containing the date, and possibly time, from which to retrieve the values. This is parsed, together with end_time, using AF.Time.AFTimeRange.

  • end_time (str or datetime) – String containing the date, and possibly time, until which to retrieve values. This is parsed, together with start_time, using AF.Time.AFTimeRange.

  • interval (str) – String containing the interval at which to extract data. This is parsed using AF.Time.AFTimeSpan.Parse.

  • filter_expression (str, optional) – Defaults to ‘’. Query on which data to include in the results. See Filtering values for more information on filter queries.

  • summary_types (int or PIConsts.SummaryType) – Type(s) of summaries of the data within the requested time range.

  • calculation_basis (int or PIConsts.CalculationBasis, optional) – Event weighting within an interval. See Event weighting and CalculationBasis for more information. Defaults to CalculationBasis.TIME_WEIGHTED.

  • filter_evaluation (int or PIConsts,ExpressionSampleType, optional) – Determines whether the filter is applied to the raw events in the database, of if it is applied to an interpolated series with a regular interval. Defaults to ExpressionSampleType.EXPRESSION_RECORDED_VALUES.

  • filter_interval (str, optional) – String containing the interval at which to extract apply the filter. This is parsed using AF.Time.AFTimeSpan.Parse.

  • time_type (int or PIConsts.TimestampCalculation, optional) – Timestamp to return for each of the requested summaries. See Summary timestamps and TimestampCalculation for more information. Defaults to TimestampCalculation.AUTO.

Returns

Dataframe with the unique timestamps as row index

and the summary name as column name.

Return type

pandas.DataFrame

interpolated_value(time)

Return a PISeries with an interpolated value at the given time

Parameters

time (str) – String containing the date, and possibly time, for which to retrieve the value. This is parsed, using AF.Time.AFTime.

Returns

A PISeries with a single row, with the corresponding time as

the index

Return type

PISeries

interpolated_values(start_time, end_time, interval, filter_expression='')

Return a PISeries of interpolated data.

Data is returned between start_time and end_time at a fixed interval. All three values are parsed by AF.Time and the first two allow for time specification relative to “now” by use of the asterisk.

filter_expression is an optional string to filter the returned values, see OSIsoft PI documentation for more information.

The AF SDK allows for inclusion of filtered data, with filtered values marked as such. At this point PIconnect does not support this and filtered values are always left out entirely.

Parameters

  • start_time (str or datetime) – Containing the date, and possibly time, from which to retrieve the values. This is parsed, together with end_time, using AF.Time.AFTimeRange.

  • end_time (str or datetime) – Containing the date, and possibly time, until which to retrieve values. This is parsed, together with start_time, using AF.Time.AFTimeRange.

  • interval (str) – String containing the interval at which to extract data. This is parsed using AF.Time.AFTimeSpan.Parse.

  • filter_expression (str, optional) – Defaults to ‘’. Query on which data to include in the results. See Filtering values for more information on filter queries.

Returns

Timeseries of the values returned by the SDK

Return type

PISeries

abstract name()
recorded_value(time, retrieval_mode=RetrievalMode.AUTO)

Return a PISeries with the recorded value at or close to the given time

Parameters

  • time (str) – String containing the date, and possibly time, for which to retrieve the value. This is parsed, using AF.Time.AFTime.

  • retrieval_mode (int or PIConsts.RetrievalMode) – Flag determining which value to return if no value available at the exact requested time.

Returns

A PISeries with a single row, with the corresponding time as

the index

Return type

PISeries

recorded_values(start_time, end_time, boundary_type='inside', filter_expression='')

Return a PISeries of recorded data.

Data is returned between the given start_time and end_time, inclusion of the boundaries is determined by the boundary_type attribute. Both start_time and end_time are parsed by AF.Time and allow for time specification relative to “now” by use of the asterisk.

By default the boundary_type is set to ‘inside’, which returns from the first value after start_time to the last value before end_time. The other options are ‘outside’, which returns from the last value before start_time to the first value before end_time, and ‘interpolate’, which interpolates the first value to the given start_time and the last value to the given end_time.

filter_expression is an optional string to filter the returned values, see OSIsoft PI documentation for more information.

The AF SDK allows for inclusion of filtered data, with filtered values marked as such. At this point PIconnect does not support this and filtered values are always left out entirely.

Parameters

  • start_time (str or datetime) – Containing the date, and possibly time, from which to retrieve the values. This is parsed, together with end_time, using AF.Time.AFTimeRange.

  • end_time (str or datetime) – Containing the date, and possibly time, until which to retrieve values. This is parsed, together with start_time, using AF.Time.AFTimeRange.

  • boundary_type (str, optional) – Defaults to ‘inside’. Key from the __boundary_types dictionary to describe how to handle the boundaries of the time range.

  • filter_expression (str, optional) – Defaults to ‘’. Query on which data to include in the results. See Filtering values for more information on filter queries.

Returns

Timeseries of the values returned by the SDK

Return type

PISeries

Raises

ValueError – If the provided boundary_type is not a valid key a ValueError is raised.

summaries(start_time, end_time, interval, summary_types, calculation_basis=CalculationBasis.TIME_WEIGHTED, time_type=TimestampCalculation.AUTO)

Return one or more summary values for each interval within a time range

Parameters
Returns

Dataframe with the unique timestamps as row index

and the summary name as column name.

Return type

pandas.DataFrame

summary(start_time, end_time, summary_types, calculation_basis=CalculationBasis.TIME_WEIGHTED, time_type=TimestampCalculation.AUTO)

Return one or more summary values over a single time range.

Parameters
Returns

Dataframe with the unique timestamps as row index

and the summary name as column name.

Return type

pandas.DataFrame

abstract units_of_measurement()
update_value(value, time=None, update_mode=UpdateMode.NO_REPLACE, buffer_mode=BufferMode.BUFFER_IF_POSSIBLE)

Update value for existing PI object.

Parameters

  • value – value type should be in cohesion with PI object or it will raise PIException: [-10702] STATE Not Found

  • time (datetime, optional) – it is not possible to set future value, it raises PIException: [-11046] Target Date in Future.

You can combine update_mode and time to change already stored value.

version = '0.1.0'
PIconnect.config module
class PIconnect.config.PIConfigContainer

Bases: object

property DEFAULT_TIMEZONE
PIconnect.time module
PIconnect.time.timestamp_to_index(timestamp)

Convert AFTime object to datetime in local timezone.

Parameters

timestamp (System.DateTime) – Timestamp in .NET format to convert to datetime.

Returns

Datetime with the timezone info from PIConfig.DEFAULT_TIMEZONE.

Return type

datetime

PIconnect.time.to_af_time(time)

Convert a time to a AFTime value.

Parameters

time (str | datetime) – Time to convert to AFTime.

Returns

Time range covered by the start and end time.

Return type

AF.Time.AFTime

PIconnect.time.to_af_time_range(start_time, end_time)

Convert a combination of start and end time to a time range.

Both start_time and end_time can be either a datetime.datetime object or a string. datetime objects are first converted to a string, before being passed to AF.Time.AFTimeRange. It is also possible to specify either end as a datetime object, and then specify the other boundary as a relative string.

Parameters

  • start_time (str | datetime) – Start time of the time range.

  • end_time (str | datetime) – End time of the time range.

Returns

Time range covered by the start and end time.

Return type

AF.Time.AFTimeRange

Contributing

Contributions are welcome, and they are greatly appreciated! Every little bit helps, and credit will always be given.

You can contribute in many ways:

Types of Contributions

Report Bugs

Report bugs at https://github.com/Hugovdberg/PIconnect/issues.

If you are reporting a bug, please include:

  • Your operating system name and version.

  • Any details about your local setup that might be helpful in troubleshooting.

  • Detailed steps to reproduce the bug.

Fix Bugs

Look through the GitHub issues for bugs. Anything tagged with “bug” and “help wanted” is open to whoever wants to implement it.

Implement Features

Look through the GitHub issues for features. Anything tagged with “enhancement” and “help wanted” is open to whoever wants to implement it.

Write Documentation

PIconnect could always use more documentation, whether as part of the official PIconnect docs, in docstrings, or even on the web in blog posts, articles, and such.

Submit Feedback

The best way to send feedback is to file an issue at https://github.com/Hugovdberg/PIconnect/issues.

If you are proposing a feature:

  • Explain in detail how it would work.

  • Keep the scope as narrow as possible, to make it easier to implement.

  • Remember that this is a volunteer-driven project, and that contributions are welcome :)

Get Started!

Ready to contribute? Here’s how to set up PIconnect for local development.

  1. Fork the PIconnect repo on GitHub.

  2. Clone your fork locally:

    $ git clone git@github.com:your_name_here/PIconnect.git

3. Install your local copy into a virtualenv. Assuming you have pipenv installed, this is how you set up your fork for local development:

$ cd PIconnect/
$ pipenv sync -d
$ pipenv install -e .

  1. Create a branch for local development:

    $ git checkout -b name-of-your-bugfix-or-feature

    Now you can make your changes locally.

5. When you’re done making changes, format the code with black, check that your changes pass pylint and the tests, including testing other Python versions with tox:

 $ black PIconnect
 $ pylint PIconnect tests
 $ python setup.py test or py.test
 $ tox

Pylint and tox will be installed automatically by pipenv.

  1. Commit your changes and push your branch to GitHub:

    $ git add .
$ git commit -m "Your detailed description of your changes."
$ git push origin name-of-your-bugfix-or-feature

  2. Submit a pull request through the GitHub website.

Pull Request Guidelines

Before you submit a pull request, check that it meets these guidelines:

  1. The pull request should include tests.

  2. If the pull request adds functionality, the docs should be updated. Put your new functionality into a function with a docstring, and add the feature to the list in README.rst.

  3. The pull request should work for Python 3.6, 3.7, 3.8 and 3.9. Testing is automated through GitHub Actions, so you get feedback on your pull request where things are not up to standards.

Tips

To run a subset of tests:

$ py.test tests.test_piconnect

Credits

Development Lead

Contributors

History

0.9.1 (2021-08-11)

  • Fixes the Exception type to swallow (related to #580)

  • Fixes missing dependency in wheel (#595)

0.9.0 (2021-08-10)

Warning

This is the final version to support python 2.7

  • Added support to write values to the databases (#573)

  • Added support for extracting Event frames from PI-AF (#587)

  • Added methods to extract a single historic value from both PIPoint and PIAFAttribute objects. (#523)

  • Added options to login to the PI Server using provided credentials (#522)

  • Added option to set the connection timeout for data extraction (#572)

  • Better loading of the configured servers (#580)

  • All data extracting functions now support both extraction using strings and datetime objects. (#574)

0.8.0 (2020-03-03)

  • Added option to configure the timezone for the returned index. Changed default from Europe/Amsterdam to UTC! Adds pytz as new dependency(#499)

  • More robust detection of the default PI AF server (#496, #501)

  • Removed pytest-runner dependency unless explicitly requested (#503)

  • Exiting the context manager for a PIAFDatabase no longer explicitly disconnects from the server, but leaves it up to SDK. (#487)

  • Various updates of the package dependencies

0.7.1 (2019-08-16)

  • Improved documentation

  • Changed PIData.PISeriesContainer to an Abstract Base Class

0.7.0 (2018-11-14)

  • Add summary, summaries, and filtered_summaries methods to PIPoint

    and PIAFAttribute

0.6.0 (2018-07-05)

0.5.1 (2017-11-25)

0.4.0 (2017-11-25)

  • First release on PyPI.

Copyrights

Even though the PIconnect package itself is licensed under the MIT license, it requires the OSIsoft PI AF SDK to actually make the connections. All copyrights to the SDK remain explicitly to OSIsoft.

OSIsoft, the OSIsoft logo and logotype, Managed PI, OSIsoft Advanced Services, OSIsoft Cloud Services, OSIsoft Connected Services, PI ACE, PI Advanced Computing Engine, PI AF SDK, PI API, PI Asset Framework, PI Audit Viewer, PI Builder, PI Cloud Connect, PI Connectors, PI Data Archive, PI DataLink, PI DataLink Server, PI Developer’s Club, PI Integrator for Business Analytics, PI Interfaces, PI JDBC driver, PI Manual Logger, PI Notifications, PI ODBC, PI OLEDB Enterprise, PI OLEDB Provider, PI OPC HDA Server, PI ProcessBook, PI SDK, PI Server, PI Square, PI System, PI System Access, PI Vision, PI Visualization Suite, PI Web API, PI WebParts, PI Web Services, RLINK and RtReports are all trademarks of OSIsoft, LLC.

Things left to do

Todo

Reject searches while not connected

(The original entry is located in /home/docs/checkouts/readthedocs.org/user_builds/piconnect/checkouts/master/PIconnect/PI.py:docstring of PIconnect.PI.PIServer.search, line 11.)

Todo

Add setter to alter displayed description

(The original entry is located in /home/docs/checkouts/readthedocs.org/user_builds/piconnect/checkouts/master/PIconnect/PI.py:docstring of PIconnect.PI.PIPoint.description, line 3.)

Todo

Move __boundary_types to PIConsts as a new enumeration

(The original entry is located in /home/docs/checkouts/readthedocs.org/user_builds/piconnect/checkouts/master/PIconnect/PIData.py:docstring of PIconnect.PIData.PISeriesContainer, line 4.)

Indices and tables