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i.LON 100 Internet Server Programmer’s Reference 9-1

9 Analog Function Block

You can use Analog Function Blocks to perform a variety of statistical operations on the

values of the data points in your network, and store the result of each operation in an output

data point. You can perform these operations on as many input data points as you like per

Analog Function Block. The operations you can perform on them include determining the

average value of the input data points, the maximum value of the input data points, the

minimum value of the input data points, the sum of the input data point values, and several

others. Each operation is described in detail later in this chapter.

You can also select a comparison function as your operation. In this case, the Analog

Function Block will compare the value of all the input data points to the value of a data point

selected as the compare data point. You can choose from a variety of comparisons that an

Analog Function Block can perform between the data points, including Greater Than, Less

Than, and Equal To. The Analog Function Block will compare the values of the compare and

input data point using that comparison, and update the output data point to a True or False

value based on the result of that comparison.

If you are using a comparison function, and your Analog Function Block has multiple input

data points, you can specify a percentage. If that percentage of the comparisons between the

input and compare data points returns True, the output data point will be set to True.

Otherwise, it will be set to False.

For example, consider a case where an Analog Function Block has five input data points and

is using Greater Than as the comparison function. Assume that the percentage is set to 50%.

If the value of the 50% (at least three) of the input data points is greater than the value of

the compare data point, the output data point will be set to True. Otherwise, it will be set to

False.

The Analog Function Block will perform the operation you have selected for it each time any

of its input data points are updated, or at a timed interval you specify. You could use these

calculated values as a part of a control system or to monitor alarm conditions based on

multiple inputs.

NOTE: Analog Function Blocks are not supported by, and can not be configured with, the

i.LON 100 Configuration Software.

9.1 AnalogFB.XML

The AnalogFB.XML file stores the configuration of the Analog Function Blocks that you have

added to the i.LON 100. You can create up to 20 Analog Function Blocks on your i.LON 100.

Each Analog Function Block is signified by an <AnalogFB> element in the XML file. You can

create Analog Function Blocks with the AnalogFBSet function, or by manually editing the

AnalogFB.XML file and downloading it to the i.LON 100 via FTP. The sections following this

example provide instructions and guidelines to assist you when doing so.

The following represents a sample AnalogFB.XML file for an i.LON 100 with one defined

Analog Function Block. This Analog Function Block determines the maximum value between

two data points, NVL_nviClaValue_1 and NVL_nviClaValue_2, and stores that value in the

value field of a data point called NVL_nvoClsValue_1.

<?xml version="1.0" ?>