Interpolated Data function (DvCHInterpolated)

This worksheet function can be used to retrieve a number of interpolated samples for a single tag at regular intervals within a time period. The function must be entered as an array formula in a range that has the appropriate number of rows and columns. You can use the Configure Interpolated Data Function dialog in DeltaV Reporter to set up a call to this function.

Syntax

DvCHInterpolated(connection, tag, show_header, columns, time_mode, period_start, period_end, samples)

Example Array Formula

=DvCHInterpolated("localhost","DeltaV=MAIN_WORKSTATION CHS250_1S/SGGN1/OUT.CV",TRUE,"Value;Timestamp;Parameter Status,IsGood;Collection Status,IsGood","Local","10/11/08 11:04:02 AM","10/12/08 11:04:02 AM","60minutes")

Function Arguments

connection

The node name of the DeltaV Continuous Historian server.

tag

The DeltaV tag for which you want to retrieve data. The tag can be text, such as FIC101.PV, or a cell reference. In the case of a cell reference (such as $A$1), the contents of the referenced cell must contain a valid tag.

show_header

A Boolean (TRUE or FALSE) that indicates whether or not you want the returned data to have a column header row.

columns

A string that defines the columns to be included in the worksheet. Column definitions are separated by semicolons. Each column definition comprises the column name and, optionally, various attributes relating to that specific column. Column attributes are separated by commas. The following columns and attributes are supported:

Column name: Timestamp
- Mode attribute: Local, GMT, or GMT ±hh:mm
Column name: Value
- For Int32, UInt32, and Float data types, the value stored by Excel is a Variant Double.
- For strings, the value stored by Excel is a Variant String.
- For enumerations, the value stored by Excel is the state name in a Variant String.
Column name: Parameter Status (that is, FfStatus)
- Mode attribute. Valid modes are:
  - Text – which yields a descriptive string, such as GoodNonCascade NonSpecific NotLimited
  - IsGood – which yields a Boolean: TRUE if the parameter status is good, or FALSE if it is not good (that is, bad or uncertain)
  - Number – which yields the raw value as an integer
Column name: Collection Status (that is, DvCHStatus)
- Mode attribute. Valid modes are:
  - Text – which yields a descriptive string
  - IsGood – which yields a Boolean: TRUE if the collection status is good (that is, 0) or FALSE if it is not good (not zero)
  - Number – which yields the raw value as an integer

time_mode

Indicates how the period_start and period_end arguments should be interpreted. The DeltaV Continuous Historian database records all times in GMT; the time_mode argument specifies what conversion, if any, should be applied to the supplied time stamp in order to convert to GMT.

Local – the time stamp is treated as being in the time zone of the client PC. Conversion to GMT takes into consideration whether the time stamp falls within daylight saving time.
GMT – no conversion is necessary
GMT ±hh:mm – the time is adjusted by the specified hh:mm; daylight saving time has no effect.

period_start: The time stamp of the start of the period. Specify period_start as text or a cell reference.

period_end: The time stamp of the end of the period. Specify period_end as text or a cell reference.

Note

If period_start is a later time than period_end, samples are retrieved in reverse chronological order from the (later) start time toward the (earlier) end time.

samples

One of the following:

The number of samples required (without quotation marks). The start and end of the time period each yield a sample; therefore, this number must be 2 or greater.
The interval between samples (enclosed in quotation marks). This is a positive number followed by a units string, which must be one of the following: hours, minutes, or seconds. If necessary, the period_end is automatically adjusted to extend the overall time period such that it is a multiple of this interval.