Asset Framework and PI System Explorer (PI Server 2018)

Understand filter expressions

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Understand filter expressions

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Last UpdatedDec 16, 2024
2 minute read

Add a filter expression to filter event values using a mathematical expression, eliminating data for which the expression evaluates as false. The following example shows a simple filter expression that removes all values over 70 from the calculation:

Code example

‘.’ < 70

You can also use any valid PI performance equation in the filter expression to build more complex expressions to remove atypical peaks in data values,

Note: Place filter expressions within two straight apostrophe symbols (Unicode character 'APOSTROPHE' (U+0027)).

Expression variables

Expression variables are limited to attributes or PI points which originate from a single Data Archive. Attributes which resolve to a static value (no data reference configured), are also acceptable. See Indirect PI point references for a complete description of possible reference syntax.

Attribute variable examples

Filter expression	What it does
‘.’	Reference to the attribute being queried.
‘Level’	Reference to the attribute Level at the same attribute hierarchy level in the element or event frame.
‘..’	Reference to the parent attribute of the attribute being queried. Only valid for nested child attributes.
‘.\|HighLimit’	Reference to the child attribute HighLimit of the attribute being queried.
‘\|Temperature’	Reference to the Temperature attribute at the top hierarchy level in the current element or event frame.
‘\\MyPIServer\sinusoid’	Absolute path to a PI point. It must be in the same Data Archive as the current queried attribute.
‘\\myAFServer\myDatabase\myElement\|myAttribute’	Absolute path to a PI AF attribute.
‘\myRootElement\|myAttribute’	Database relative path to a PI AF attribute.

PI point variable examples

Filter expression	What it does
‘.’	Reference to the PI point being queried.
‘sinusoid’	Reference to the PI point sinusoid in the same Data Archive.
sinusoid

Asset Framework and PI System Explorer (PI Server 2018)