Industrial Automation
Automation Industrielle
Industrielle Automation
4 Access to devices
4.3.4 OPC
Historical Data Access
Prof. Dr. H. Kirrmann
ABB Research Centre, Baden, Switzerland
2012 May, HK
HDA: Overview
OPC Common
Overview: usage and specifications
OPC as an integration tool
Clients and Servers: configuration
OPC Technology, client and custom interface
OPC Data Access
Overview: browsing the server
Objects, types and properties
Communication model
Simple Programming Example
Standard and components
OPC Alarms and Events Specification
Overview: definitions and objects
Events
Alarm Conditions
Automation Interface
OPC Historical Data Specification
Overview
Industrial Automation
OPC HDA 4.3.4 - 2
Historians: An introduction
The role of HDA will become clearer
after a first glance at historians
The process database
decouples the plant from the analysis tools.
It contains recent and historical data.
Invensys (Wonderware) Archestra
Industrial Automation
OPC HDA 4.3.4 - 3
Historians Example
GE Fanuc/Intellution iHistorian (iFix...)
Questions to the historian:
What was the value of FIC101 last week ?
What was the flow average during October ?
Which were the daily averages in October ?
What was the total flow in each month ?
How much fuel did we use for the batch ?
Give the answer in form of tables,
pie diagrams, spreadsheet, reports
Features:
Unlimited Point Collection
Sub-Second Data Collection Rates
Enhanced Data Compression
True Thin Client Administration
Fault Tolerant Architecture
Industrial Automation
data collection, archiving and retrieval
report generation
computations (e.g. VBScript)
secure access (FDA 21 CFR 11)
20'000 actions/ s,
up to 100'000 data points
OPC HDA 4.3.4 - 4
Historians: Market
2003 Global Information Management Market by Industry
2%
11%
21%
1%
6%
13%
13%
12%
Chemical
Food and Beverage
Petroleum
Pulp and Paper
Pharmaceuticals
Power
Textiles
Waste and Water
Other
21%
Industrial Automation
OPC HDA 4.3.4 - 6
Historians: Players
 ABB
Information Manager (formerly Enterprise Historian, bases on Oracle)
 AIP/PPA (embedded) Historian is another product (small player)
 AspenTech
InfoPlus.21

Complete offering with wide range of accompanying applications and services
 Very good user interface

OSISoft PI 3.4

Largest installed base (perceived as de facto standard)
 Easy-to-use
 Perceived low cost (PI 3.4: 1 Mio data points / 80'000 /s)

GE-Fanuc Intellution iHistorian

Relatively new to market. Product created with Mountain Systems
 Causing a stir for OSIsoft, AspenTech on pricing

Some small players

Honeywell (POMS) Uniformance
 Invensys (Wonderware) IndustrialSQL 8.0
 Rockwell Automation (RSBizWare) Historian
 Siemens (WinCC) Historian (bases on MS SQL Server)
Industrial Automation
OPC HDA 4.3.4 - 7
Historian implementation
application
OPC HDA
ODBC/SQL and OPC HDA are
complementary
log organisation
"SQL"
history
database
collector
corrections
operator actions
"OPC"
field data
Industrial Automation
OPC HDA 4.3.4 - 8
HDA: Historical Data Access
HDA Clients
e.g. Trend Analysis
e.g. Event Logger
independent
processes
OPC HDA
Server
hidden
calculations
history
database
raw and
ordered data
collector
proprietary
data acquisition
OPC DA Server
Field device
Industrial Automation
Field device
OPC HDA 4.3.4 - 9
HDA: Purpose
An OPC HDA server gives access to a historical data base (logs) in which data from the
process have been collected and time-stamped, possibly through an OPC DA interface.
The OPC HDA interface clients, such as trend analysis, product tracking or data mining,
that require ordered access these data logs.
The OPC HDA interface allows to:
- browse the historical data base
- retrieve data through proper filtering, e.g. by date range, by identity, by property
- build aggregates over the retrieved data, such as average, minimum, maximum.
- enter new entries, correct entries or remove entries
- enter / delete annotations in the history data base
Industrial Automation
OPC HDA 4.3.4 - 10
HDA: Raw log
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Industrial Automation
By definition, values are registered when they change.
(even if data are acquired by periodic polling)
Data in the historical database are identified by their
• itemID (here, represented by their name),
• value, (of the respective type)
• quality (good, stale, bad), and
• timestamp (UTC).
OPC HDA 4.3.4 - 11
HDA: How to reduce raw data (even before HDA comes into play)
Tag values are sent to the OPC DA server when they change (on events), the collector
records these data in a log that is organized as a circular buffer.
Since a log has a limited storage capacity, data are reduced by several means:
1) if a variable is received more often than the log's minimal storage interval
(e.g. 1s), the log keeps the latest of all values of the interval
2) if (and only if) a received variable changed by more than the "exception
deviation" (e.g. 5%, analog values only), it is entered into the log.
3) if a variable changed by less than the exception deviation, it may be forced into
the log after the log's maximum storage interval (e.g. 4 s) elapsed.
min time
max time
max time
max time
max
exception
deviation
min
time
= process value (event)
= log entry
Two situations can occur:
- the time scale of the log is smaller than that of the trend display
in this case, values have to be interpolated to be displayed correctly
Industrial Automation
OPC HDA 4.3.4 - 12
HDA Application: Trend Display
Parameters:
log: how were data sampled
• time scale (with possible offset, zoom, pan)
• amplitude scale (low range, high range, scale units)
• style: smoothed, stepped, filled (several ways to display the same data)
• extrapolate: how to display values not received (e.g. because they did not yet change)
Industrial Automation
OPC HDA 4.3.4 - 13
HDA: More logs
A log registers only one data point !
log 2.1
log 1
log 2.2
(log templates can be used for
several datapoints)
log 2
Data in the log may be:
Measured values (original, from the OPC DA)
Calculated values
Corrected values (replaced or inserted)
Annotations (explanation strings)
raw log
Collector
(OPC DA Client)
other servers
OPC DA Server
Field device
XML / CSV
Field device
Industrial Automation
OPC HDA 4.3.4 - 14
HDA: Hierarchical logs
long-term log
1 hour_forever
 5.2 MB / Year
1
2
3 27 28 29 30
september octobre
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
october
1 mn_7 days log
 6 MB
d-7
1s_24 hours log:
50 traces @ 12 B
 52 MB
23
24
1
2
3
d-6
4
5
d-5
6
7
8
d-4
9
10
d-3
11
12
13
A hierarchical log is built on the data contained in the parent log.
To reduce the log size, several aggregations can be applied:
- record only maximum, minimum, average over a period, etc...
Industrial Automation
d-2
14
15
16
yesterday
17
18
19
today
20
21
22
Actual data
OPC HDA 4.3.4 - 15
HDA role
An HDA server allows to browse the logs and filter the logs to be read.
It can filter them according to their attributes, such as
name of the datapoints, type of the datapoint, engineering units,....
An HDA server then selects the logs to be read.
An HDA can then read the logs, defining a certain period
(Start time, End Time, and the maximum number of entries to be retrieved.
When reading the log, the HDA server can process the log by applying aggregations
The "min time", "deviation", "max time" rules used to collect raw data is also used
as an aggregation to build new logs.
Therefore, hierarchical logs can be built out of a raw log by an OPC HDA service.
Do not confound aggregates and attributes.....
Industrial Automation
OPC HDA 4.3.4 - 16
HDA: Server
The client can query the HDA server for its capabilities, and in particular:
- which LocaleID (national languages) the server supports (as in DA and AE servers)
- which attributes the server supports (the attributes of its items is a subset thereof)
- which aggregates the server support (and the client can request)
- if the server supports correction / deletion of data (synchronous and/or asynchronous)
- if the server supports insertion of annotations (synchronous and/or asynchronous)
Many capabilities of the HDA server are optional.
Industrial Automation
OPC HDA 4.3.4 - 17
HDA: Browsing: structure
Like the DA and AE interfaces, OPC HDA server offers a browser with methods allowing
to navigate up and down, and to retrieve branches and leaves at each position.
If filters are defined at its creation time, an HDA browser only browse for items with
specific attributes (e.g. Engineering Units = m/s). The filtering attributes are additive.
HDA (contrarily to DA and AE) allows several browsers, each with its different filter.
root
Leaves
Object
Log 1
Object
Log 2
Area 5
Log 3
Area 51
Area 52
Industrial Automation
OPC HDA 4.3.4 - 18
HDA: General attributes of the items
Code Attributes
Description
1
2
3
4
DATA_TYPE
DESCRIPTION
ENG_UNITS
STEPPED
5
6
7
ARCHIVING
DERIVE_EQUATION
NODE_NAME
8
PROCESS_NAME
9
SOURCE_NAME
10
SOURCE_TYPE
11
NORMAL_MAXIMUM
12
NORMAL_MINIMUM
13
ITEMID
data type for the item. See the definition of a VARIANT for valid values (VT_R4, etc.)
text that describes the item.
label to use in displays to define the units for the item (e.g., kg/s).
whether data from the history repository should be displayed as interpolated (sloped lines
between points) or stepped (vertically-connected horizontal lines between points) data.
whether historian is recording data for this item (0 means no).
equation to be used by a derived item to calculate its value. This is a free-form string.
machine which is the source for the item. This is intended to be the broadest category for
defining sources. For an OPC Data Access Server source, this is the node name or IP
address of the server. For non-OPC sources, the meaning of this field is server-specific.
process which is the source for the item. This is intended to the second-broadest category
for defining sources. For an OPC DA server, this would be the registered server name.
For non-OPC sources, the meaning of this field is server-specific.
name of the item on the source. For an OPC DA server, this is the ItemID.
For non-OPC sources, the meaning of this field is server-specific.
sort of source produces the data for the item. For an OPC DA server, this would be "OPC".
For non-OPC sources, the meaning of this field is server-specific.
upper limit for the normal value range for the item, is used for trend display default scaling
and exception deviation limit calculations, should be the normal high value for the item.
lower limit for the normal value range for the item, is used for trend display default scaling
and exception deviation limit calculations, should be the normal low value for the item.
item identifier. This is used to allow filtering in the CreateBrowse method.
Industrial Automation
OPC HDA 4.3.4 - 19
HDA: Attributes that affect how data are archived
Code Attributes
Data Type
Description
14
Max Time Interval
VT_FILETIME
15
Min Time Interval
VT_FILETIME
16
Exception Deviation
VT_R8
17
Exception Deviation Type
VT_I2
18
High Entry Limit
VT_R8
19
Low Entry Limit
VT_R8
Specifies the maximum interval between data points in the
history repository regardless of their value change.A new value
shall be stored in history whenever OPCHDA_MAX_TIME_INT
seconds have passed since the last value stored for the item.
Specifies the minimum interval between data points in the
history repository regardless of their value change.A new value
shall be not be stored in history unless
OPCHDA_MIN_TIME_INT seconds have passed since the last
value stored for the item.
Specifies the minimum amount that the data for the item must
change in order for the change to be reported to the history
database. See OPCHDA_EXCEPTION_DEV_TYPE for the
specific meaning of this field.
Specifies whether the OPCHDA_EXCEPTION_DEV is given
as an absolute value, percent of span, or percent of value. The
span is defined as OPCHDA_HIGH_ENTRY_LIMIT OPCHDA_LOW_ENTRY_LIMIT.
Specifies the highest valid value for the item. A value for the
item that is above OPCHDA_HIGH_ENTRY_LIMIT cannot be
entered into history. This is the top of the span.
Specifies the lowest valid value for the item. A value for the
item that is below OPCHDA_LOW_ENTRY_LIMIT cannot be
entered into history. This is the zero for the span.
Industrial Automation
OPC HDA 4.3.4 - 20
HDA: Selecting the items
Each server has only one group of items, the collection OPCHDAItems.
By adding an OPCHDAItemID to that collection, the client defines its client handle and
receives the server's server handle.
The OPCHDAItemID (a string) should be retrieved by using the browser (like in DA or
AE), since entering a string directly is unsafe.
The server handle is used to access the log.
Read operations are applied to the whole collection OPCHDAItems.
....
Set colOPCHDAItems = MyOPCHDAServer.OPCHDAItems
colOPCHDAItems.AddItem OPCHDAItemID ClientHandle
colOPCHDAItems.SyncReadRaw .....
Industrial Automation
OPC HDA 4.3.4 - 21
HDA: Reading the data
When reading the data, the client has the choice to read synchronously or
asynchronously (if the server permits the latter).
The client specifies the time interval (Start time and end time) and whether the end
values of that interval shall be included.
The client has the choice to read the raw data or to apply an aggregation to the read
data. The aggregations (see next slides) allow to reduce data.
Industrial Automation
OPC HDA 4.3.4 - 22
HDA: Aggregates
Symbol
0 NoAggregate
1 Interpolative
2 Total
3 Average
4 TimeAverage
5 Count
6 StDev
7 MinimumActualTime
8 Minimum
9 MaximumActualTime
10 Maximum
11 Start
12 End
13 Delta
14 RegSlope
15 RegConst
16 RegDev
17 Variance
18 Range
19 DurationGood
20 DurationBad
21 PercentGood
22 PercentBad
23 WorstQuality
24 Annotations
Description
Do not retrieve an aggregate (use only start time - stop time and filtering).
Get interpolated values.
Get the totalized value (time integral) of the data over the resample interval.
Get the average data over the resample interval.
Get the time weighted average data over the resample interval.
Get the number of raw values over the resample interval.
Get the standard deviation over the resample interval.
Get the minimum value in the resample interval and the timestamp of the minimum value.
Get the minimum value in the resample interval.
Get the maximum value in the resample interval and the timestamp of the maximum value.
Get the maximum value in the resample interval.
Get the value at the beginning of the resample interval (time stamp).
Get the value at the end of the resample interval (time stamp of end of the interval).
Get the difference between the first and last value in the resample interval.
Get the slope of the regression line over the resample interval.
Get the intercept of the regression line over the resample interval, (time start of interval).
Get the standard deviation of the regression line over the resample interval.
Get the variance over the sample interval .
Get the difference between the minimum and maximum value over the sample interval.
Get the duration (in seconds) of time in the interval during which the data is good.
Get the duration (in seconds) of time in the interval during which the data is bad.
Get the percent of data (1 = 100 %) in the interval which has good quality.
Get the percent of data (1 = 100 %) in the interval which has bad quality.
Get the worst quality of data in the interval.
Get the number of annotations in the interval.
Industrial Automation
OPC HDA 4.3.4 - 23
HDA interpolation
interpolation is an aggregate used when the time scale of the derived log is smaller than
that of the parent log.
= parent log
= filtered log
resample interval of the new log
time
This is useful to display smoothly trend diagrams.
Industrial Automation
OPC HDA 4.3.4 - 24
HDA corrections and annotations
These features are seldom implemented.
Basically, the values are accessed using the server handles that
OPCHDAItems.AddItem returned.
Industrial Automation
OPC HDA 4.3.4 - 25
HDA Automation Model
OPC Common
Overview: usage and specifications
OPC as an integration tool
Clients and Servers: configuration
OPC Technology, client and custom interface
OPC Data Access
Overview: browsing the server
Objects, types and properties
Communication model
Simple Programming Example
Standard and components
OPC Alarms and Events Specification
Overview: definitions and objects
Events
Alarm Conditions
Automation Model
OPC Historical Data Specification
Overview
Automation Model
Industrial Automation
OPC HDA 4.3.4 - 26
HDA: Automation Interface summary
OPCHDAServer
An instance of an OPC HDA Server. An OPCHDAServer object must be
created to can get references to other objects.
OPCHDAItems (col)
A collection containing all the OPCHDAItem objects this client has
created within the scope of the OPCHDAServer object
OPCHDAItem
OPCHDAItem
An object that maintains the item’s definition. Note the Custom Interface
does not provide a separate Item Object.
OPCHDABrowsers
An object that browses item names in the server’s configuration.
OPCHDAHistory
An collection containing a series of either OPCHDAValue or
OPCHDAEntry objects, representing historical values of an item.
OPCHDAValue
OPCHDAValue
An object that represents a discrete historical value for an item or an
attribute.
OPCHDAEntry
OPCHDAEntry
An object that extends the OPCHDAValue object to include additional
information
Industrial Automation
OPC HDA 4.3.4 - 27
HDA Browsing and filtering
The filter criteria are based on attributes (see the preceding slides).
Attributes cannot be modified afterwards.
Set MyOPCHDABrowser = MyOPCHDAServer.Createbrowser
(NumCriteria, AttributeIDs, operatorCode, Filters, Errors
MyOPCHDABrowser.MoveDown (MyOPCHDABrowser.OPCHDABranches(1))
Items = MyOPCHDABrowser.OPCHDAItems
.... list these items
Industrial Automation
OPC HDA 4.3.4 - 28
HDA: Object Interfaces (1)
Industrial Automation
OPC HDA 4.3.4 - 29
HDA: Object Interfaces (2)
Industrial Automation
OPC HDA 4.3.4 - 30
To probe further….
OPC Foundation:
Specifications http://www.opcfoundation.org
SoftwareToolbox
Examples in Visual Basic
http://www.softwaretoolbox.com/Tech_Support/TechExpertiseCenter/OPC/opc.html
The Code Project
OPC and .NET
http://www.codeproject.com/useritems/opcdotnet.asp
Matrikon
Free client and server:
http://www.matrikon.com
WinTech
Toolkit for an OPC server
http://www.win-tech.com/html/opcstk.htm
NewAge Automation
Toolkit for an OPC server
http://www.newageautomation.com
Industrial Automation
OPC HDA 4.3.4 - 31
To probe further….
OPC Foundation:
Specifications http://www.opcfoundation.org
SoftwareToolbox
Examples in Visual Basic
http://www.softwaretoolbox.com/Tech_Support/TechExpertiseCenter/OPC/opc.html
The Code Project
OPC and .NET
http://www.codeproject.com/useritems/opcdotnet.asp
Matrikon
Free client and server:
http://www.matrikon.com
WinTech
Toolkit for an OPC server
http://www.win-tech.com/html/opcstk.htm
NewAge Automation
Toolkit for an OPC server
http://www.newageautomation.com
Industrial Automation
OPC HDA 4.3.4 - 32