Operators - ABB SM2000 User Manual Supplement

2 MATH CONFIGURATION
2.1 Math Block Description
Notes.
• Up to twelve Math Blocks, configured individually
using the 'Math Pad' – see Fig. 2.2.
• Each Math result has its own Long and Short Tags
and Engineering Range
• Up to 18 different preset functions – Table 2.4
• Constants up to three decimal places
• Maximum equation length – 40 characters
• Up to three digital signals per equation
Individual recording channel signals, analog and digital sources
can be combined in a Math Block to produce a customized
recording channel or retransmission source.
Typical examples include adding/subtracting the values of a
number of analog sources together to form one recording
channel.
More complex blocks can also be implemented that determine
relative humidity, mass flow or zirconia oxygen concentration.
Digital signals can be used in Math Blocks to enable/disable the
output when certain conditions are true.
Math result (Assigned to recording
channels, retransmission outputs)
Constant (Any numerical value, up to 3 d.p.)
Source (Digital) – see Table 2.3
Notes.
• Operators are evaluated from left to right.
The above equation is evaluated as:
• Functions cannot be nested within other functions.
To enter an equation requiring nested functions it is necessary to use another math block,
e.g. to evaluate the equation:
a1 + a2
52.4 – a3
•
•
• Digital signals (md1 to md3) are evaluated as 0 (inactive) and 1 (active).
Thus in the following example:
m1 = a1 + a2*md1
the sum of (a1+ a2) is set to zero if the digital input md1 is also zero.
2
m1 = a1 + 52.4 * Log(a2) – md2
Source (Analog)
– see Table 2.2
Function – see Table 2.4
[(a1 + 52.4)* Log(a2)] – md2 and NOT as a1 + (52.4* Log(a2)) – md2.
proceed as follows:
Enter math block 1 as m1 = a1 + a2/m2
Enter math block 2 as m2 = 52.4 – a3
Fig. 2.1 Typical Math Block
2.2 Typical Math Block – Fig. 2.1
Each math block comprises any number of sources, constants,
operators and functions, to a maximum length of 40 characters,
as indicated in Fig. 2.1.
Possible operators, sources and functions are listed in
Tables 2.1 to 2.4
2.3 Operators – Table 2.1
O p r e t a r o D e s c i r t p o i
+ A d d
* M t l u p i y l
Table 2.1 Operators
2.4 Constants
Math blocks may contain any number of constants, each with a
limit of three decimal places, up to the maximum of 40
characters for the whole block. The maximum range of each
constant is 9999 to – 999

Operators

– see Table 2.1
19 characters total (Max 40)
n O p r e t a r o D e s c i r
– S u t b a r
/ D v i d i
t p o i n
t c
e