Math Configuration; Introduction; Standard Math Block - ABB C1300 User Manual Supplement

2 MATH CONFIGURATION

2.1 Introduction

Overview.
• Four user-configurable math blocks – can be used independently or cascaded together.
• Each math block can be configured to perform one of seven functions:
Standard math block (arithmetic operations) – add, subtract, divide, multiply, high select, low select and median
Relative humidity (RH) – from wet and dry bulb sensor temperature
Mass flow 1 – calculation of mass flow from volume
Mass flow 2 – calculation of mass flow from differential pressure
High value – holds the maximum value measured on an input variable
Low value – holds the minimum value measured on an input variable
Real time average – averages a continually varying input over a set period of time.
• Inputs can be either variables or constants.

2.1.1 Standard Math Block

There are four programmable math blocks. Each math block is constructed using up to four operands and three operators. The four
operands can be configured as process variable inputs, set points, constants or other math results. The three operators can be
configured for addition, subtraction, multiplication, division, high value selection, low value selection, median (mid-value selection) or
end math block.
Note. The elements in each equation are calculated sequentially. It is therefore important to enter the elements in the correct
order to obtain the result required e.g. 2 + 3 x 4 = 20 (Not14). If median is selected as element 2, element 4 automatically
becomes median and element 6 automatically becomes end.
The example below shows the construction of a math block for the following equation:
2