====== IEC 62541-011 OPC Unified Architecture - Part 11: Historical Access ======
[[dido:public:ra:xapend:xapend.b_stds:tech:iec:start| return to the IEC Standards ]]

<table>
<caption>Data sheet for OPC Unified Architecture - Part 11: Historical Access</caption>
| Title                      | OPC Unified Architecture - Part 11: Historical Access |
| Version                    | 2020|
| Document Number            | 62541-11|
| Release Date               | 2020  |
| Reference                  | [[https://webstore.iec.ch/publication/61129]] |
</table>

  : **Note**: The following is an excerpt from the official IEC catalog. It is provided here as a convenience and is not authoritative. Refer to the original document as the authoritative reference.

===== Abstract =====

IEC 62541-11:2020 is part of the OPC Unified Architecture standard series and defines the information model associated with Historical Access (HA). It particularly includes additional and complementary descriptions of the NodeClasses and Attributes needed for Historical Access, additional standard Properties, and other information and behaviour.

The complete **''AddressSpace Model''** including all NodeClasses and Attributes is specified in [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-3]]. The predefined Information Model is defined in [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-5]]. The Services to detect and access historical data and events, and description of the **''ExtensibleParameter''** types are specified in [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-4]]. This document includes functionality to compute and return Aggregates like minimum, maximum, average, etc. The Information Model and the concrete working of Aggregates are defined in [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-13]]. This third edition cancels and replaces the second edition published in 2015. 

This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition:
  : a) a new method for determining the first historical point has been added
  : b) added clarifications on how to **''add''**, **''insert''**, **''modify''**, and **''delete''** annotations.

See also:

  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-1]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-2]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-3]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-4]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-5]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-6]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-7]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-8]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-9]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-10]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-12]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-13]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-14]]
  * [[dido:public:ra:xapend:xapend.b_stds:tech:iec:62541-100]]

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