User`s manual

1-4 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 0 09-15-05
mathematical operation or function on them to yield a sin-
gle numerical value or digital state.
When entering an equation, you must follow a strict
format so that the E2 can properly understand and use the
equation. This section will explain how to build equations
in detail.
1.4.1 Types of Equations and
Where Equations are Entered
There are three different screens in the Flexible Com-
biner setup for output equations.
• Screen 4, the Output Eq screen, is where equations
that determine the output’s value are entered.
• Screen 5, the Delay Eq screen, is only visible if dig-
ital outputs are present. Equations that determine
the ON and OFF delays for digital outputs are
entered in this screen.
• Screen 6, the PW Eq screen, is only visible if one or
more digital outputs have been set up as “one-shot”
outputs. Equations that determine the pulse width
and period are entered in this screen.
Each of these screens lists the application outputs that
apply to it along with a 40-character field where the equa-
tion must be entered.
Section 2, Building Equations, provides a detailed
explanation of equation syntax in the Flexible Combiner
application.
Using the Second Line
If the “Show Eq Line 2” field is set to “Yes” in Screen
1, a “Line 2” field will be directly underneath each equa-
tion to expand the total equation size to 80 characters. If an
equation takes more than 40 characters to write, simply
write the first 40 characters in the first line and write the
remaining ones in the second line as if it were an extension
of the first line.
You can split variable names, constants, etc. between
the two lines with no problem. For example, if while writ-
ing an equation you have only two spaces left at the end of
line 1 and you must write the variable name “AO3,” sim-
ply write “AO” in the last two spaces and the “3” as the
first character of line two. When E2 parses the equation, it
will push line 1 and line 2 together into one long string,
and it will recognize the variable name as AO3.
1.4.2 Output Equations
Screen 4 of the Flexible Combiner setup screens is
where equations that determine the output’s value are
entered. An output equation typically involves using math-
ematical operators or functions to combine or compare one
or more analog or digital outputs to yield a new output
result. Table 1-1 gives some useful examples of sensor
control applications used in refrigeration/HVAC applica-
tions and the equations used to achieve them. See Section
2, Building Equations, for a more detailed explanation of
equation components and functions.
Figure 1-5
- Flexible Combiner Output Equations
Desired
Function
Equation
Averaging
three tempera-
ture sensors
AI1 through
AI3, and pass-
ing the result
to AO4.
AO4:
AVG(AI1,AI2,AI3)
Turn on an
exhaust fan at
DO2 when a
temperature
AI1 rises
above 120°F,
and turn it off
again when
the tempera-
ture falls
below 100°F.
DO2:
CUTINOUT(AI1,120DF,100DF,DO2)
Table 1-1 - Commonly Used Equation Examples