Instruction Manual

5.2.1.1 DataServerList

Use the DataServerList function to retrieve a list of data points that you have added to the

i.LON 100 Data Server. The Data Server List function accepts an empty string as the

contents of its <Data> parameter. If you supply an empty string as the <Data> parameter,

the list returned by the function will contain an entry for every data point in the Data

Server.

Alternatively, you can specify a subset of data points to be listed by filling the properties

described in Table 9 into the <Data> parameter you supply to the function.

Table 9 DataServerList Input Properties

Parameter Description

Enter the type of data point to be listed in the return string (NVL or

NVC). Leave this property empty to display all data point types.

Optional. Enter a string of 16 comma-separated Boolean values. This

string will be compared to the <UCPTsettings> string defined for

each data point. If at least one set bit in this string matches the

<UCPTsettings> string defined for a data point, then that data point

will be included in the list returned by the function.

The <UCPTsettings> property for a data point is defined when it is

added to the Data Server, and can be written to with the

DataServerSet function, which is described later in this chapter.

Enter the index number of the first data point to be listed in the

return string.

Enter the maximum number of data points to be included in the

return string.

The example below requests that the function return a list of up to 50 NVL data points,

starting with index number 0.

In this example, the function returns a <DpNVL> element at the beginning of the return

string, because the <UCPTdataPointType> requested in the input is NVL. This contains

global information about the data point type requested in the list. Or, if the property had

been filled in as NVC, a <DpNVC> element would have been returned. Each of these

elements includes the following child elements:

•

<SCPTobjMajVer> and <SCPTobjMinVer>. Child elements identifying the major and minor

version numbers of the firmware implementation the Data Server application is using.

• <UCPTlastUpdate>. A timestamp indicating the last time the Data Server was written

to. This timestamp is expressed in UTC format, as per the ISO 8601 standard.

• <UCPTlifeTime>. This property defines how old (in seconds) the value of a data

point of the specified type can be before the Data Server retrieves a new data value

from the driver when an application requests the value of a given data point. If this

parameter is set to 0, the values of the data points will be copied from the i.LON 100

Data Server when an application requests them, and no update will be requested

from the driver. If this parameter is set to a positive value, the i.LON 100 Data

Server will poll the driver for the current value of a data point each time an

application requests it, and the time interval defined by the property has expired.

i.LON 100 Internet Server Program5-10 mer’s Reference