Span - Metasys - LIT-12011942 - "" - Software Application - Metasys Open Data Server - 10.1

Metasys Open Data Server Help
Product
Building Automation Systems > Databases and Data Servers > Metasys Open Data Server
Document type
User Guide
Document number
LIT-12011942
Version
10.1
Revision date
2019-10-14

The Span block applies a range and extrapolated values to an input to produce an output. This table describes the Span block components:

Table 1. Span Blocks

Symbol

Description

IN

Input

IL

Input Low

OL

Output Low

IH

Input High

OH

Output High

The Span block creates a linear relationship between the low input/output and high input/output pair. If the Input for the Span block falls between the low and high input, the Output of the Span block is found on the line between the low and high pairs.

The following example shows a graphical picture of how the Span block works:

Figure 1. Span Block Example 1

The line connecting the low and high pairs (blue line) represents the linear relationship between them. When you enter an Input for the Span block, the logic finds where the line crosses that input and provides the corresponding output. (The output must lie on the thick blue line.) Using the figure above, if you enter 5 for the Span block Input, the block would find 5 on the Input axis and provide an output of 5.5 because that is where the line crosses an Input value of 5. (The green line shows this relationship.)

If the Span block is set up to Clamp (see Editing Span Blocks) the value of the Output, the Output of the block is restricted to the range between (and including) the low and high Output you enter for the block. Range clamping is the default setting. For example, assume you are using the values in the figure below and have clamping set to True. If you enter an Input of 5, you still generate an Output of 5.5, because the original line crosses an Input of 5 at 5.5, which is between 4 and 8 (low and high output). If you enter an Input of 12, you generate an Output of 8, because where the original line crosses an Input of 12 is higher than the high output (see where thin blue and thin green lines intersect). If clamping is True for both high and low, the output must lie on the newly drawn thick blue line.

Figure 2. Span Block Example 2

The Span block works for the reverse span as well (if the Output High is lower than the Output Low). See Editing Blocks in Edit Mode for information on editing Span blocks.