Emerson E2 Einstein User Manual

026-1620 Rev 3 06-JAN-2011

E2 User’s Manual Supplement: Flexible Combiner

Programming

Retail Solutions

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Kennesaw, GA 30144

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and the products described herein, at any time without notice or obligation.

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undesired operation.

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Class A Product Information for Einstein, E2 Controllers:
The Retail Solutions Einstein and E2 controllers are Class A products. In a domestic

environment this product may cause radio interference in which case the user may be
required to take adequate measures. This covers:

• All Einstein family product types: RX - Refrigeration Controller
(830-xxxx), BX - Building/HVAC Controller (831-xxxx), and all ver­sion models: (300, 400, 500).

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Table of Contents

1 FLEXIBLE COMBINER.......................................................................................................................................... 1-1

1.1 O

VERVIEW ................................................................................................................................................................. 1-1

1.2 H

OW IT WORKS......................................................................................................................................................... 1-1

1.2.1 Example.............................................................................................................................................................. 1-1

1.3 I

NPUT AND OUTPUT ASSIGNMENT............................................................................................................................. 1-2

1.3.1 Programming the Inputs and Outputs................................................................................................................ 1-2

1.3.1.1 Adding a Flexible Combiner Application................................................................................................................ 1-2

1.3.1.2 Flexible Combiner General Setup............................................................................................................................ 1-2

1.3.1.3 Inputs........................................................................................................................................................................ 1-3

1.3.1.4 Outputs..................................................................................................................................................................... 1-3

1.4 EQUATIONS................................................................................................................................................................ 1-4

1.4.1 Types of Equations and Where Equations are Entered..................................................................................... 1-4

1.4.2 Output Equations ............................................................................................................................................... 1-4

1.4.3 Delay Equations................................................................................................................................................. 1-5

1.4.4 Pulse Width Equations....................................................................................................................................... 1-5

1.5 E

NGINEERING UNITS.................................................................................................................................................. 1-6

1.6 D

ESCRIPTION PROPERTIES ......................................................................................................................................... 1-7

1.7 A

LARMS..................................................................................................................................................................... 1-7

2 BUILDING EQUATIONS ........................................................................................................................................ 2-1

2.1 I

NPUT AND OUTPUT VARIABLES ............................................................................................................................... 2-1

2.2 C

ONSTANTS ............................................................................................................................................................... 2-2

2.2.1 Constants and Engineering Units...................................................................................................................... 2-2

2.2.2 Specifying a Constant’s Engineering Unit with Type Suffixes........................................................................... 2-3

2.2.3 Time Constants................................................................................................................................................... 2-3

2.3 O

PERATORS ............................................................................................................................................................... 2-5

2.3.1 Multiple Operators and Parenthesis.................................................................................................................. 2-5

2.4 F

UNCTIONS ................................................................................................................................................................ 2-6

2.4.1 Extended Math Functions .................................................................................................................................. 2-7

2.4.2 Extended Logical Functions............................................................................................................................... 2-9

2.4.3 Logarithm Functions. ....................................................................................................................................... 2-10

2.4.4 Trigonometry Functions................................................................................................................................... 2-10

2.4.5 Analog Change Detection................................................................................................................................ 2-11

2.4.6 Unit Conversion and Temperature Functions ................................................................................................. 2-11

2.4.7 Extended Digital Functions ............................................................................................................................. 2-12

2.4.8 Time and Date Functions................................................................................................................................. 2-12

2.4.9 IF Functions..................................................................................................................................................... 2-14

3 TESTING AND TROUBLESHOOTING EQUATIONS....................................................................................... 3-1

3.1 C

HECKING FOR ERRORS ............................................................................................................................................ 3-1

3.1.1 Equation Troubleshooting Tips.......................................................................................................................... 3-2

APPENDIX...................................................................................................................................................................... A-1

E2 User’s Manual Supplement: Flexible Combiner Table of Contents • v

1 Flexible Combiner

1.1 Overview

The Flexible Combiner application, a new feature of
E2 versions 2.20 and above, is a highly advanced and ver­satile I/O control program used to combine multiple ana­log and digital input values using programmed equations
similar to those used in spreadsheets.

A Flexible Combiner application may have up to eight
analog outputs and four digital outputs, each of whose val­ues are determined by user-programmed equations that
mathematically combine up to eight analog inputs and
eight digital inputs. Four of the analog outputs have the
ability to remember their output state over an E2 power
cycle. Additionally, up to four alarms can be set up whose
trigger and alarm delays are equations. Alarm type, prior­ity, and the message for each alarm are user-configurable.

Equations used to calculate output values and time
delays may use mathematical combinations of any of the
Flexible Combiner’s analog and digital inputs, as well as
numeric and named constants, operators, functions, and
even rudimentary if-then logic functions.

For control of digital outputs the Flexible Combiner
also supports separate equations that determine ON and
OFF delays. The Flexible Combiner may also be pro­grammed to operate a digital output as a PWM (pulse­width modulation) output. In this instance, the equation
written for a PWM output determines its period and pulse
width.

characters in length) that the E2 “parses,” or decodes, to
determine the output’s value.

Equations must be entered by the user and require
some basic knowledge of the E2’s scripting language,
which is further explained in this section of the manual.

Outputs

The outputs of the Flexible Combiner are the real-time
results of the application’s equations. Each output’s value
is determined by the equation assigned to it in the Flexible
Combiner application.

Outputs of the Flexible Combiner application may be
tied to relay or analog output points on a Retail Solutions
output board, or they may be passed along to the inputs of
other E2 applications.

1.2.1 Example

Figure 1-1 shows a symbolic diagram of an example
Flexible Combiner application. In this diagram, there are
two equations shown: one for analog output AO1 and
another for digital output DO2.

The equation in AO1 is set up to make analog output
AO1 equal to the average value of the two analog inputs
AI1 and AI7. The equation adds these two values together
and then divides the result by two.

The equation in DO2 performs a logical AND function
on digital inputs DI1 through DI3. When all of these out­puts are ON, the value of DO2 will be ON; otherwise, if
one or more of the inputs are OFF, DO2 will be off.

1.2 How It Works

A typical Flexible Combiner application consists of

three types of components: inputs, equations, and out-

puts.
Inputs

Inputs for a Flexible Combiner applications may be
sensor values from input points on a MultiFlex input board
or outputs from other software applications in the E2.
Inputs are the building blocks you will use to create the
control function you need.

A Flexible Combiner output may be configured with
up to eight analog inputs and eight digital inputs.

Equations

Equations are used to combine or otherwise mathemat­ically alter one or more inputs from the Flexible Combiner
to create an output that performs a desired function. Each
output has its own equation (a string of characters up to 80

Overview Overview • 1-1

Figure 1-1

- Flexible Combiner Control Diagram

1.3 Input and Output
Assignment

The first step in setting up a Flexible Combiner is con-

figuring the application’s inputs.

The first question that must be answered before input
assignment can begin is “What do I want the Flexible
Combiner to do?” Will it choose the highest value from a
series of temperature sensors? Will it calculate enthalpy
from temperature and humidity sensors? Will it read a set
of proofs and turn an output ON if more than half of them
fail?

When you have determined this, make a note of the
following:

• How many inputs of each type you will need (ana­log and digital)

• How many outputs of each type you will need (ana­log and digital)

5. When the E2 asks “Do you wish to edit the new
applications now?” press
to the first setup screen of the application you
added (or, if you added multiple applications, it
will take you to the first application you added).

. The E2 will take you

1.3.1.2 Flexible Combiner General Setup

• The types of analog inputs that will be used (tem­perature, pressure, etc.)

• For analog outputs, the range of values you want
each output to vary between (0-5V, 0-10V, 1-5V,
etc.)

• For digital outputs, whether you want each output
to be a simple ON/OFF digital output or a one-shot
output.

The next step is to assign all the inputs and outputs to
the numbered input and output slots in the Flexible Com­biner application.

1.3.1 Programming the Inputs
and Outputs

1.3.1.1 Adding a Flexible Combiner
Application

If you haven’t added a Flexible Combiner application
yet, you will need to create it in the E2’s Add Application
screen.

1. Press

2. With the cursor highlighting the Type field, press

3. Enter the number of Flexible Combiners yo u

4. Press

 to access the Add Application

screen.

 and choose “Flexible Combiner” from the
Look-Up Table. Note: If Flexible Combiner does

not appear in this list, it may be because your E2
is not version 2.20 or higher.

wish to add in the “How many?” field.

 to add the new applications.

Figure 1-2

will set up the general parameters required to further
define the application’s functions.

Name

function in the Name field.

Num of AI

biner will use in this field.

Num of AO

biner will use in this field.

Num of DI

biner will use in this field.

Num of DO

biner will use in this field.

Show Eq Line 2

40 characters each that may be used to enter its equation.
Since an equation rarely exceeds 40 characters, it is usu­ally safe to hide the second line from display to make the
screen easier to read. This will be explained in further
detail in Section 1.4.1; for now, leave this field set to NO.

DO1-DO8 T y pe

- Flexible Combiner General Setup

The first screen of the Flexible Combiner is where you

Enter a short description of the Flexible Combiner’s

Enter the number of analog inputs the Flexible Com-

Enter the number of analog outputs the Flexible Com-

Enter the number of digital inputs the Flexible Com-

Enter the number of digital outputs the Flexible Com-

Each output in the Flexible Combiner has two lines of

The eight DO1-DO8 Type fields are used to specify

1-2 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

whether each digital output will be a simple ON/OFF digi­tal output or a one-shot pulse output. Choose the desired
output type here.

DO1-DO8 Trigger

If any of the DO1-DO8 Type fields were set up as one­shot outputs, choose the method the Flexible Combiner
will use to generate pulses. The choices are:

• Edge - Pulse is generated when the application tran-

sitions the output from OFF to ON.

• Inv Edge - Pulse is generated when the application

transitions the output from ON to OFF.

• Both Edge - Pulse is generated every time a state

transition occurs, whether it is OFF to ON or ON to
OFF.

Press

 to proceed to the Inputs screen.

1.3.1.3 Inputs

here. Refer to the E2 User’s Manual (P/N 026-1610) for
more details.

Once all inputs are defined, make a note of the names
of each input you defined (AI1-AI8 and DI1-DI8). These
names are the ones that are used when building equations.

When finished, press
screen.

 to proceed to the Outputs

1.3.1.4 Outputs

Figure 1-3

the number of analog and digital inputs you specified in
Screen 1: General.

tion:Output.” If you wish to use the output from another
E2 application as an input for the Flexible Combiner appli-

cation, use the Look-Up Table (
troller, application name, and output name for each field in
the definition.

from a MultiFlex input board, press
the I/O format, and select

format to Board and Point. Then, enter the board and point
address of the input point in each field.

configured yet from the Input Summary screen, you will
need to do so before entering its board and point address

- Flexible Combiner Inputs

The Inputs screen will show the input definitions for

The default input format is “Controller:Applica-

) to select the con-

If you want an input to be a board and point address

 to change

 from the menu to change the

NOTE: If a point you enter in this manner has not been

Figure 1-4 - Flexible Combiner Outputs

The Outputs screen will show the output definitions for
the number of analog and digital outputs you specified in
Screen 1: General.

The default output format is “Controller: Application:
Input.” If you wish to use the input of another E2 applica­tion as the destination for a Flexible Combiner’s output

value, use the Look-Up Table (
troller, application name, and input name for each field in
the definition.

If you want an output to be a board and point address
from a MultiFlex output board, press
the I/O format, and select
format to Board and Point. Then, enter the board and point

address of the relay or analog point in each field.

ON DELAY and OFF DELAY

Each digital output will have two corresponding out­puts, one for its on delay and one for its off delay. It is not
necessary to configure these outputs. They are only there
so the value of the on and off delays may be logged, used
in generic alarm control, and presented in status screens.

Once all inputs and outputs are configured, you will be
ready to complete the Flexible Combiner programming by
building equations.

) to select the con-

 to change

 from the menu to change the

Input and Output Assignment Input and Output Assignment • 1-3

1.4 Equations

The value of each output in a Flexible Combiner appli­cation is determined by its own equation, which usually
takes the values of one or more inputs and performs a
mathematical operation or function on them to yield a sin­gle 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 Com­biner 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 dig­ital 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 equa­tion 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 equa­tion 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 writ­ing an equation you have only two spaces left at the end of
line 1 and you must write the variable name “AO3,” sim­ply 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

Figure 1-5

where equations that determine the output’s value are
entered. An output equation typically involves using math­ematical 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 applica­tions and the equations used to achieve them. See Section
2, Building Equations, for a more detailed explanation of
equation components and functions.

Function

Averaging
three tempera­ture sensors
AI1 through
AI3, and pass­ing the result
to AO4.

The output of
analog mem­ory equation
is stored so
the value is
consistent
across
reboots. This
is useful for
implementing
long term
counters or
timers.

Table 1-1 - Commonly Used Equation Examples

- Flexible Combiner Output Equations

Screen 4 of the Flexible Combiner setup screens is

Desired

AO4:

AVG(AI1,AI2,AI3)

AM1:
If (DI1 = ON, AM1 + 1, AM1)
Using AM1 as a counter that increments
when DI1 is ON.
The current value of AM1 will be preserved
even if the E2 is rebooted.

Equation

1-4 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

Desired

Function

Turn on an
exhaust fan at
DO2 when a
temperature
AI1 rises
above 120°F,
and turn it off
again when
the tempera­ture falls
below 100°F.

AND combi­nation of digi­tal inputs DI1
through DI8

Table 1-1

- Commonly Used Equation Examples

DO2:

CUTINOUT(AI1,120DF,100DF,DO2)

DO1:

AND(DI1:DI8)

Equation

1.4.3 Delay Equations

analog value representing number of seconds.

If you have digital outputs and would like to use ON

and OFF delays, enter constants or equations in these
fields. See Section 2, Building Equations, for a more
detailed explanation of equation components and func­tions.

Desired

Function

Output DO1
has a 60 sec­ond ON delay
and a 60 sec­ond OFF
delay

Output DO2
has a 90-min­ute ON delay
and a 90-min­ute OFF
delay.

DO1 OFF Delay:

60

DO2 OFF Delay:

60

DO2 OFF Delay

01:30

DO2: OFF Delay

01:30

Equation

Figure 1-6 - Flexible Combiner Delay Equations

The digital outputs of a Flex Combiner application
have optional equations that can be used to program ON
and OFF delays. If the outputs are directly controlling
devices, ON and OFF delays can help minimize switching
by turning the output ON or OFF only when the equation
result that caused the transition remains in that state for
longer than the delay.

In other words, if an OFF delay is 30 seconds, and the
result of the input equation transitions from ON to OFF,
the result must remain OFF for thirty seconds before its
corresponding output actually changes state.

Delay equations do not actually have to be equations.
Most commonly, they will be constants. However, a delay
equation can be any mathematical expression (including
inputs, constants, operators, or functions) that results in an

Output DO3
uses a 5 min­ute delay
between the
hours of 9
p.m. and mid­night, and a 3
minute delay
otherwise.

DO3:

IF(TIME()>9:00p,00:05:00,00:03:00)

Table 1-2 - Commonly Used Equation Examples

1.4.4 Pulse Width Equations

Figure 1-7 - Flexible Combiner Pulse Width Equations

If one or more digital inputs have been configured to

be “One Shot” type outputs, the width of the ON pulse is

Equations Equations • 1-5

determined by the value of the Pulse Width equations.
When a one-shot output is called to be ON, the Flex Com­biner will run this equation and use the resulting value as
the number of seconds the output will pulse ON.

Like delay equations, pulse width equations most com­monly will only be constant values, since there is usually
little need for variance in one-shot pulse width. However,
a delay equation can be any mathematical expression
(including inputs, constants, operators, or functions) that
results in an analog value representing number of sec-

onds.

1.5 Engineering Units

Desired

Function

5 second
pulse on DO1

2 minute
pulse on DO2

15 second
pulse width
on DO3
unless the cur­rent time is
before 8 a.m.,
in which case
the pulse
width is 10
seconds

DO1 PulseWidth:

5

DO2 PulseWidth

00:02

DO3 PulseWidth

IF((TIME()<08:00a)=TRUE,15,10)

Equation

Table 1-3 - Commonly Used Equation Examples

Figure 1-8 - Engineering Units

The engineering units used for each analog input and
output must be defined in Screen 7 of the Flexible Com­biner setup screens: the Eng Units screen.

The units chosen for inputs are particularly important
in determining how the value will be scaled and used in
equations (see Section 2.2.1, Constants and Engineering
Units).

For outputs, setting an engineering unit determines
how it is displayed in the Flex Combiner status screen. If a
unit is chosen for an output that is different from the
default engineering unit of the same type used by the E2 in
General Controller Info, the chosen type is substituted for
the default type on this screen only.

In other words, if AO1 is set to display in DF in the
Flexible Combiner cell but the default temperature unit for
the E2 is in DC, the output value will only be displayed in
DF on the Flex Combiner status screen — everywhere else
(including the Flex Combiner Summary Screen) it will
display in DC.

1-6 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

1.6 Description Properties

1.7 Alarms

Figure 1-9

descriptions of the associated inputs and outputs entered
by the user. Pertinent descriptions can be entered that
explain inputs and outputs to aid in understanding the
intent of the programming performed in the flexible com­biner. (Descriptions for analog memory outputs appear
only in expanded status.)

connection is made to the output of another application,
the description is automatically filled in with the applica­ton name and property of that output. If text is entered for
an input and a new connection is made, the text is not
automatically changed. This applies to inputs only; out­puts are not affected.

- Flexible Combiner Description Properties

The Description Properties screen will show the

If text is not entered for a description for an input and a

Figure 1-10 - Flexible Combiner Alarm Setup

The alarm output and delay equations control the trig­ger of the alarm and how long to delay before setting an
advisory in the advisory log. These equations are executed
exactly like analog and digital outputs. The alarm output
equations combined with the delay equations control the
outputs AL1 - AL4. The results of the delay equation are
sent to outputs AL1 - AL4 DELAY. The alarm type can be
set to either Notice or Alarm. The alarm priority sets the
priority of the advisory generated. For a complete list of
advisory text, see the Appendix section.

Description Properties Description Properties • 1-7

2 Building Equations

Equations are made up of different combinations of

four major elements: inputs, defined in the Flexible Com-
biner application, constants such as numerical values used
in mathematical computations, operators such as plus
signs (+) or greater than signs (>) used to perform basic
math functions, and functions such as if-then statements
or boolean logic (AND/OR).

2.1 Input and Output Vari­ables

Variable Name Description

AIx (x=input
number)

DIx (x=input
number)

AOx (x=output
number)

DOx (x=output
number)

Table 2-1 - Input and Output Variable Names

The most commonly used variables in an equation will
be the Flexible Combiner’s input values. These are repre­sented in equations by their variable names, AI1-AI8 and
DI1-DI8.

To use input values in an equation, just enter their
names (AI for analog input or DI for digital input, and a
number from 1 through 8 corresponding to the input num­ber). The E2 will look for input variable names and create
a link to the input’s value when parsing the equation.

Analog Input Values and SI Units

The value of an AI input will always be equal to the
current input value in the E2’s internal standard (SI)
units. This is important to remember because any mathe­matical operations that involve this value will use its SI
units, which may cause the equation to be wrong if you are
assuming the wrong units.

Example: AI1 is reading a value of 212°F. If you
wanted to write an equation that added 10°F to the value

The analog value of input AIx, in SI
units

The digital state of input DIx, converted
to analog:

1.0 if input is ON

0.0 if input is OFF
The analog value of output AOx, in SI

units
The digital state of output DOx, con-

verted to analog:

1.0 if input is ON

0.0 if input is OFF

of AI1, the equation “AI1+10” would be incorrect because
this would add 10 to the value of AI in Celsius, since E2’s
SI unit for temperature is Celsius.

The way to correct this would be convert the number
10 to an equivalent number of degrees C (“AI1+5.6”), or
else use a type suffix so the E2 knows you want to add 10
degrees (“AI1+10DDF”). Type suffixes are explained in
further detail in Section 2.2.2, Specifying a Constant’s
Engineering Unit with Type Suffixes.

Table 2-2 lists the SI units used by E2:

Input Type Choices SI Unit

Temperature degrees Fahrenheit (DF)

degrees Celsius (DC)

Change in
Temperature

Pressure inches of water (INW)

Change in
Pressure

Air Velocity feet per minute (FPM)

Liquid
Velocity

Volume
Flow

delta degrees Fahrenheit
(DDF)
delta degrees Celsius
(DDC)

centimeters of water
(CMW)
pounds per sq. inch (PSI)
bars (BAR)
kilopascals (KPA)
pascals (PA)

delta inches of water
(DINW)
delta centimeters of water
(DCMW)
delta pounds per sq. inch
(DPSI)
delta bars (DBAR)
delta kilopascals (DKPA)
delta pascals (DPA)

meters per minute (MPM)
meters per second (MPS)

gallons per minute
(GPM)
liters per second (LPS)

cubic feet per minute
(CFM)
cubic meters per second
(CMS)

degrees C (DC)

delta degrees C
(DDC)

pascals (PA)

delta pascals
(DPA)

meters per sec­onds (MPS)

liters per sec­ond (LPS)

cubic meters
per second

Table 2-2 - SI Units for Analog Inputs

Input and Output Variables Input and Output Variables • 2-1

Input Type Choices SI Unit

Electrical
Current

Power Rate watts (W)

Power Con­sumption

Lumination foot-candles (FTC)

Table 2-2

amperes (A)
milliamperes (MA)

kilowatts (KW)
watt-hours (WH)

kilowatt-hours (KWH)

lux (LUX)

- SI Units for Analog Inputs

amperes (A)

watts (W)

watt-hours
(WH)

lux (LUX)

Digital Input Values and Analog Conversion

A digital input value is converted to a numerical value
when read into Flexible Combiner equations. A digital
input that is ON is treated as a unitless analog value of 1.0.
An OFF is treated as an analog value of 0.0. Logical oper­ators such as AND, OR, XOR, and other functions typi­cally used to combine digital inputs are all designed to
treat non-zero values as ONs for purposes of logic, and
zero values as OFFs.

EXAMPLE EQUATIONS: INPUTS

Equation Description

AI4 The real-time value of AI4
AI1+AI2+AI3 Total sum of inputs AI1,

AI2, and AI3

Numeric

Constant

Examples Description

Types

Integers 7, -30 Whole numbers. A minus

sign in front will make it
negative.

Non-integers 1.0, -0.3,

3.14

Exponential
Numbers

1.1E04

-4.5E-12

Also called decimal or float­ing-point values. A minus
sign in front will make it
negative.

Large numbers can be
entered in exponential for­mat. Format should be a
number with one significant
digit to the left of the deci­mal, followed by an E, then
followed by an integer that
corresponds to the power of
ten the number will be mul­tiplied by. Example: 1.1E06
is 1.1 times 10 to the sixth
power, or 1,100,000.

A minus sign to the left of
the number makes the num­ber negative. A minus sign
in between the E and the
exponent specifies a nega­tive exponent.

Table 2-4 - Numeric Constants

Table 2-3 - Equation Examples: Inputs

2.2 Constants

In addition to inputs, Flexible Combiner equations will
typically require use of constants. These can be either
numeric constants (entered as numbers and used as num­bers), named consents (named strings that are parsed as
numbers), or time constants (times of day used in com­parisons). Table 2-4 and T able 2-5 show the dif ferent types

Named

Constant

PI The value of pi (3.1415926535897)
TRUE 1.0 (to signify a logical TRUE)
FALSE 0.0 (to signify a logical FALSE)
ON 1.0 (to signify a logical ON)

Description

of numeric and named constants.

OFF 0.0 (to signify a logical OFF)

Table 2-5 - Named Constants

2.2.1 Constants and Engineering
Units

Numerical and named constants are assumed to be

2-2 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

unitless numbers. In other words, a “3.0” in an equation by
itself is not assumed to be 3.0 degrees or kilowatts. How­ever, when used with a function or operator that involves
inputs of a specific type, the result of the operation or
function will use the inputs’ engineering unit designation.

For example, if analog input AI6 is a 0-100% humidity
sensor that is currently reading a humidity of 50%, the
result of the equation “AI6 / 5” will result in an output
value of 10%, even though the number 5 has no unit.

2.2.2 Specifying a Constant’s
Engineering Unit with Type Suffixes

Occasionally you may want to be specific about a con­stant’s engineering units. The equation parser supports the
use of a type suffix at the end of a constant to specify a
particular engineering unit. T able 2-6 lists all type suffixes
recognized by the Flexible Combiner ’s equation parser.

T ype suffixes must be placed directly after the constant
with no spaces in between the constant and the suffix (i.e.
75DF, not 75 DF).

Suffix Unit Suffix Unit

DF degrees F % percent
DC degrees C W watts

DDF delta degrees F

(use this suffix

for offsets)

DDC delta degrees C

(use this suffix

for offsets)
DFH °F per hour KWH kilowatt-hours
DFC °C per hour FTC foot-candles
DFM °F per minute LUX lux
DCM °C per minute PPM parts per million
INW inches of water OHM ohms

CMW cm of water RPM revolutions per

PSI pounds per

square inch

BAR bars DINW differential

KPA kilopascals DCMW differential cm of

PA pascals DPSI differential pres-

RH relative humidity DBAR differential in

FPM feet per minute DKPA differential in

Table 2-6 - Type Suffixes for Flexible Combiner Constants

KW kilowatts

WH watt-hours

minute

RPMM RPM per minute

inches of water

water

sure in PSI

bars

kilopascals

Suffix Unit Suffix Unit

MPM meters per min-

ute

MPS meters per sec-

ond

GPM gallons per min-

ute

LPS liters per second CF cubic feet

CFM cubic feet per

minute

CMS cubic meters

per second

V volts CCFH cubic centi-feet

A amps FT feet

MA milliamps M meters

PCT percent

Table 2-6

- Type Suffixes for Flexible Combiner Constants

DPA differential in

pascals

GAL gallons

Lliters

CM cubic meter

CCF cubic centi-feet

per hour

It is important to note that when type suffixes are used
that are different from the E2’s internal SI values, they are
“converted” to the SI units behind the scenes. For exam­ple, the equation “AI1+0.2BAR” actually adds 20,000 to
the raw value of AI1 (0.2 bars converted to pascals, or
20,000PA).

T ype Suffixes for Temperature Offsets (DDF and DDC)

If you are using a constant in an equation that is being
used to offset the value of a temperature sensor, you must
use the delta degrees suffixes (DDF and DDC), not the
standard temperature suffixes (DF and DC). A constant
with a DF or DC suffix is interpreted as a literal tempera­ture and converted before the math operation is performed,
so an equation like AI1+10DF is interpreted as “AI1 plus
the value of 10DF converted to Celsius (12.2).” The cor­rect way to write this would be AI1+10DDF, which would
add 10°F to the value of AI1 before converting the entire
equation to SI units.

Use the DDF and DDC suffixes in every equation that
uses basic math in conjunction with temperature offsets.

2.2.3 Time Constants

Used in delay equations and pulse width (PW) equa­tions, constants representing times of day or delay time
durations can be entered into equations in a variety of
ways:

• As a duration in HH:MM (hours/minutes).

Example: “01:45” sets the time delay to 1 hour, 45
minutes (6300 seconds).

• As a duration in HH:MM:SS (hours/minutes/
seconds). Example: “01:00:00” sets the time delay
to 1 hour (3600 seconds). Use this format for min-

Constants Constants • 2-3

ute/seconds by entering “00” for the hour (example:
“00:30:00” for 30 minutes).

• As a time of day in HH:MMx, where x is “a” if the

time is a.m. or “p” if the time is p.m. This is con­verted to a number of seconds after midnight.
Example: 04:00a is converted to 14400 seconds.

In all cases, time constants are all converted to a num­ber of seconds when used by the Flex Combiner, so that
mathematical operations like “00:01:00*2” results in 120
(60 seconds multiplied by 2).

In the case of a time constant in HH:MMx format, this
can be used along with the TIME() function to do compar­isons between the current time and the setpoint. For exam­ple, IF((TIME()>06:00p)=TRUE,60,50) compares the
current TIME, which returns the time in a number of sec­onds since midnight, to 06:00p, which is converted to
21600 seconds.

EXAMPLE EQUATIONS: INPUTS AND

CONSTANTS

Equation Description

AI4+60 The value of AI4 plus 60.
(PI*(10M^2))*AI2 Assuming AI2 is a linear

sensor whose output reflects
a water level position in
meters, this equation calcu­lates the volume of a cylin­drical tank whose radius is
10 meters. The constant PI is
multiplied by the radius
squared (10M^2) to yield the
circular area of the tank, and
this value is multiplied with
AI2 to yield volume.

AI1+(3DDF*DI2) Assuming AI1 is a tempera-

ture sensor, this equation
adds three degrees Fahren­heit to the value of AI1 when
DI2 is ON. Because ON is
equal to 1.0, then 3DDF *1.0
= 3DDF . When DI2 is OFF
(0.0), the expression 3DDF *

0.0 = 0DDF

Table 2-7 - Equation Examples: Inputs Using Constants

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2.3 Operators

Operators are symbols in equations that perform cer­tain mathematical or logical operations. The most recog­nizable (and perhaps most common) example of operators

Operator Description Examples

+

-

*

/
^
=

<>

>
<

>=
<=

!

NOT

&&

||

Adds two values 4+2 result: 6

Subtracts two values 4-2 result: 2

Multiplies two values 4*2 result: 8

Divides two values 4/2 result: 2

Exponential. The value on the left is raised to the power of the value on the right. 4^2 result: 16

Equality comparison of two values. Result is 1.0 if the two values are equa l, 0.0 if the va lues
are not equal.

Inequality comparison of two values. Result is 1.0 if the two values are not equal, 0.0 if the
values are equal.

Greater than comparison of two values. Result is 1.0 if the value to the left of the sign is
greater than the value to the right of the sign. If they are equal, or if the value to the right is
greater, the result is 0.0

Less than comparison of two values. Result is 1.0 if the value to the right of the sign is
greater than the value to the left of the sign. If they are equal, or if the value to the left is
greater, the result is 0.0

Same as greater than (>) except the result will also be 1.0 if the two values are equal. 4>=2 result: 1.0

Same as less than (<) except the result will also be 1.0 if the two values are equal. 4<=2 result: 0.0

Digital inversion of the value to the right of this sign. If the value is non-zero, the result is

0.0. If the value is zero, the result is 1.0.
Same as !, only using a different format. The value to be inverted must be put in parenthesis

next to the NOT operator (see example).
Logical AND. If the values to the right and left of these symbols are both non-zero numbers,

the result will be 1.0. Otherwise, if one or both values are 0, the result will be 0.0.

Logical OR. If either of the values to the left or right of these symbols are non-zero num­bers, the result is 1.0. If both are zero, the result is 0.0

are plus (+) and minus (-) signs. An operator is typically
placed between two inputs and/or constants in an equation
and yield a single value. T able 2-8 lists the operators avail­able in Flexible Combiner.

4+3+2 result: 9

4-3-2 result: -1

4*3*2 result: 24

4/3/2 result: 0.67

4^3^2 result: 4096
4=2 result: 0.0

4=3+1 result: 1.0
4<>2 result: 1.0

4<>3+1 result: 0.0
4>2 result: 1.0

4>3+1 result: 0.0

4<2 result: 0.0
4<3+1 result: 0.0
3<5 result: 1.0

4>=3+1 result: 1.0

4<=3+1 result: 1.0
!0 result: 1.0

!7 result: 0.0
NOT(0) result: 1.0

NOT(7) result: 0.0
4&&2 result: 1.0

4&&0 result: 0.0
0&&0 result: 0.0

4||2 result: 1.0
4||0 result: 1.0
0||0 result: 0.0

Table 2-8 - Operators

2.3.1 Multiple Operators and
Parenthesis

Often an equation will contain more than one operator.
The order in which these operators are used can be signifi­cant and may cause error if not arranged correctly.

When parsing an equation, the E2 follows a specific
order when multiple operators are present:

Operators Operators • 2-5

1. All exponent (^) operators, from left to right.

2. All multiplication and division (* and /) opera­tors, from left to right.

3. All addition and subtraction (+ and -) operators,
from left to right.

4. All greater than/less than operators (<,>,<=, and
>=), from left to right.

5. All equality and inequality operators (=,<>) from

left to right.

6. All logical operators (!, NOT , &&, ||) from left to
right.

If you cannot arrange an equation’s operators in a way
that parses them in the order you need (or if you simply
want to remove all doubt), you may use parenthesis to
specify a different order of operator execution. Expres­sions that are in parenthesis are executed first before any
operators outside of parenthesis are used. For example,
“5+2*3” without parenthesis results in 11 because the
multiplication is executed first before the addition. How­ever, in the equation “(5+2)*3” the addition is executed
first because it is in parenthesis, resulting in 21.

Equations and operators in parenthesis can themselves
contain other operators and equations in parenthesis. For
example “((5+2)*3)^2” executes the addition first, fol­lowed by the multiplication, and finally the exponent,
resulting in 441.

EXAMPLE EQUATIONS: INPUTS, CONSTANTS,

AND OPERA TORS

Equation Description

AI4+60 The value of AI4 plus 60.

2.4 Functions

Equations for most applications can be built using
nothing but inputs, constants, and operators. However, in
some cases it is not always practical or easy to use nothing
but these components (and in some cases, the equation
you’d have to build would exceed the 80-character limit).
Furthermore, you may sometimes need equations to do
more complicated things (such as converting a floating­point number to an integer or converting a temperature to
dewpoint) that cannot be handled with operators alone.

For these reasons, the Flexible Combiner offers a large
number of functions that can be used in output equations.
A function is essentially a small mathematical formula that
accepts one or more variables as inputs and returns a
numeric result.

In an equation, a function typically takes the form of
the name of the function followed by a set of parenthesis
that contain the value or values the function will use as
inputs. The values inside the parenthesis of a function may
be constants or inputs.

Functions are always evaluated first in an equation
(from left to right, unless parenthesis are used) before
operators are executed.

!DI1=DI2 The expression DI1=DI2

returns a 1.0 when both
inputs are ON and a 0.0 if
only one or the other is ON.
The “!” at the beginning of
this equation then inverts the
result of that expression. The
final result is a logical XOR
of DI1 and DI2. (Note: this
can be done more elegantly
with the XOR function,
which is explained later in
this section).

(DI1&&DI2)*AI1 Because DI1&&DI2 is in

parenthesis, the logical AND
of DI1 and DI2 is performed
first. The result of this is
multiplied with AI1. This
means the output will be
equal to AI1 (1.0*AI1) when
DI1 and DI2 are both ON,
and zero (0.0*AI1) when one
or both are OFF .

Table 2-9 - Equation Examples: Inputs Using Constants

2-6 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

2.4.1 Extended Math Functions

Function Description Examples

MOD(number , divisor)

ABS(number)

FRAC(value)

INT(value)

CEILING(value)

FLOOR(value)

TRUNC(value)

ROUND(value)

SCALE (value, low1, high1,

low2, high2)

LIMIT (value, low, high)

VAR(range)

STDDEV(range)

Divides the number by the divisor, and returns the
modulo (or the “remainder”) of the division operation.
In the example MOD(16,5), the modulo is 1 because 5
goes into 16 three times with a remainder of 1.

Returns the absolute value of the number. ABS(-14) result: 14

Returns the decimal part of the number, and retains the
sign (positive or negative).

Returns the integer part of the number, always round­ing DOWN to the next lowest integer (even when the
number is negative).

Returns the integer part of the number, rounded in
whichever direction is away from zero (i.e. up to the
next highest integer when positive, and down to the
next lowest integer when negative).

Returns the integer part of the number, rounded in
whichever direction is toward zero (i.e. down to the
next lowest integer when positive, and up to the next
highest integer when negative).

Returns the portion to the left of the decimal without
rounding up or down.

Rounds the value off to an integer using standard rules
of rounding (for positive numbers, 0.5 or above
rounds the integer UP, less than 0.5 rounds down; for
negative numbers, 0.5 or above rounds DOWN, less
than 0.5 rounds UP).

Returns a number between low2 and high2 that is lin­early proportional to where the value is in regards to
low1 and high1. Note that if the value is out of the
range of low1 and high1, a “Bad Value” error is gener­ated in the equation.

Limits the highest and lowest possible values of the
number. If the value is above the high number in this
limit, the result will be equal to the high number . If the
value is below the low number in this limit, the result
will be equal to the low number.

Returns the variance (mean squared deviation) for all
values in parenthesis. Range can be a set of constants
or input variable separated by commas, or a range of
inputs designated by a colon between the two ends of
the range (e.g. AI1:AI7).

Returns the standard deviation for all values in paren­thesis. Range can be a set of constants or input vari­able separated by commas, or a range of inputs
designated by a colon between the two ends of the
range (e.g. AI1:AI7).

MOD(16,5) result: 1
MOD(16.7,5) result: 1.7
MOD(4,2) result: 0

ABS(7.7) result: 7.7
FRAC(-6.75) result: -0.75

FRAC(12) result: 0.0
INT(6.75) result: 6

INT(0.99) result: 0
INT(-7.98) result: -8
INT(-7.11) result: -8

CEIL(6.75) result: 7
CEIL(0.04) result: 1
CEIL(-7.98) result: -8
CEIL(-7.11) result: -8

FLOOR(6.75) result: 6
FLOOR(0.04) result: 0
FLOOR(-7.98) result: -7
FLOOR(-7.11) result: -7

TRUNC(6.75) result: 6
TRUNC(0.04) result: 0
TRUNC(-7.98) result: -7
TRUNC(-7.11) result: -7

ROUND(6.75) result: 7
ROUND(0.04) result: 0
ROUND(-7.98) result: -8
ROUND(-7.11) result: -7

SCALE(5,0,10,0,3) result: 1.5
SCALE(150,0,10,0,100) result: ERROR

LIMIT(0.5,0,1) result: 0.5
LIMIT(3,0,1) result: 1
LIMIT(-4,2,10) result: 2

VAR(AI1,AI4)
VAR(AI1:AI7)

STDDEV(AI1,AI4)
STDDEV(AI1:AI7)

Table 2-10 - Extended Math Functions

Functions Functions • 2-7

Function Description Examples

MEDIAN(range)

SUMSQ(range)

PROD(range)

MAX(range)

MIN(range)

AVG(range)

SUM(range)

RAND(low,high)

Returns the median of all values in parenthesis. Range
can be a set of constants or input variable separated by
commas, or a range of inputs designated by a colon
between the two ends of the range (e.g. AI1:AI7).

Returns the sum-square of all values in parenthesis.
Each input or constant is squared, and then added
together. Range can be a set of constants or input vari­able separated by commas, or a range of inputs desig­nated by a colon between the two ends of the range
(e.g. AI1:AI7).

Returns the product of all values in the range multi­plied together. Range can be a set of constants or input
variable separated by commas, or a range of inputs
designated by a colon between the two ends of the
range (e.g. AI1:AI7).

Returns the maximum value of all values in the range.
Range can be a set of constants or input variable sepa­rated by commas, or a range of inputs designated by a
colon between the two ends of the range (e.g.
AI1:AI7).

Returns the minimum value of all values in the range.
Range can be a set of constants or input variable sepa­rated by commas, or a range of inputs designated by a
colon between the two ends of the range (e.g.
AI1:AI7).

Returns the average value of all values in the range.
Range can be a set of constants or input variable sepa­rated by commas, or a range of inputs designated by a
colon between the two ends of the range (e.g.
AI1:AI7).

Returns the sum of all values in the range. Range can
be a set of constants or input variable separated by
commas, or a range of inputs designated by a colon
between the two ends of the range (e.g. AI1:AI7).

Returns a random number between low and high every
time the algorithm is updated (every few seconds).

MEDIAN(3,7,8,14) result: 7.5
MEDIAN(AI1,AI4)
MEDIAN(AI1:AI7)

SUMSQ(5,4,3) result: 50
SUMSQ(AI1:AI7) result: sum-square of
all seven inputs

PROD(2,3,4) result: 24
PROD(AI1,AI4)
PROD(AI1:AI7)

MAX(2,5,7,14) result: 14
MAX(AI1,AI4)
MAX(AI1:AI7)

MIN(2,5,7,14) result: 2
MIN(AI1,AI4)
MIN(AI1:AI7)

AVG(2,5,7,14) result: 7
AVG(AI1,AI4)
AVG(AI1:AI7)

SUM(2,5,7,14) result: 28
SUM(AI1,AI4)
SUM(AI1:AI7)

RAND(1,10) result: random number
from 1 to 10

Table 2-10

- Extended Math Functions

2-8 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

2.4.2 Extended Logical Functions

Function Description Examples

CUTINOUT(test, low, high,

between)

COUNT(range)

VOTE(range)

AND(range)

OR(range)

XOR(range)

Returns a 1.0 or a 0.0 based on the following:
If test is below low, the result is 0.0
If test is above high, the result is 1.0
If test is between the value of low and high, the result
will be equal to between. This should be filled by the
name of the same output you are building the equation
for so that when test is between, the output remains in
whatever state it’s in, thus creating a hysteresis
between the cut-in and cut-out setpoints.

Returns the number of values in the specified range
that are non-zero. T ypically used with d igital inputs to
count the number of ON inputs. Range can be a set of
constants or input variable separated by commas, or a
range of inputs designated by a colon between the two
ends of the range (e.g. DI1:DI7).

Returns a 1.0 if more that 50% of the values in the
range are non-zero, otherwise returns 0.0. This means
if the range contains an even number of values, the
number of non-zero inputs must be more than half to
yield a result of 1.0. Range can be a set of constants or
input variable separated by commas, or a range of
inputs designated by a colon between the two ends of
the range (e.g. DI1:DI7).

Returns a 1.0 only when all values in the range are
non-zero, and 0.0 if one or all values are zero. Range
can be a set of constants or input variable separated by
commas, or a range of inputs designated by a colon
between the two ends of the range (e.g. DI1:DI7).

Returns a 1.0 when one or all values in the range are
non-zero, and 0.0 if all values are zero. Range can be a
set of constants or input variable separated by com­mas, or a range of inputs designated by a colon
between the two ends of the range (e.g. DI1:DI7).

Same as OR, except returns 0.0 when all values are
non-zero.

CUTINOUT(-4,5,12,DO1) result: 0.0
(low)
CUTINOUT(14,5,12,DO1) result: 1.0
(high)
CUTINOUT(7,5,12,DO1) result: DO1
(between)

COUNT(0,0,1,0,1) result: 2
COUNT(0,0,0,0) result: 0
COUNT(DI1,DI4)
COUNT(DI1:DI7)

VOTE(0,0,1,0) result: 0.0
VOTE(0,0,1,1) result: 0.0 (not more
than half non-zero in range)
VOTE(1,1,1,0) result: 1.0
VOTE(DI1,DI4)
VOTE(DI1:DI7)

AND(1,1) result: 1.0
AND(0,1) result: 0.0
AND(1,1,1,1,0) result: 0.0
AND(DI1,DI4)
AND(DI1:DI7)

OR(1,1) result: 1.0
OR(0,1) result: 1.0
OR(0,0,0,0,0) result: 0.0
OR(DI1,DI4)
OR(DI1:DI7)

XOR(1,1) result: 0.0
XOR(0,1) result: 1.0
XOR(0,0,0,0,0) result: 0.0
XOR(DI1,DI4)
XOR(DI1:DI7)

Table 2-11 - Extended Math Functions

Functions Functions • 2-9

2.4.3 Logarithm Functions

Function Description Examples

SQRT(value)

POWER(value,power)

LOG10(value)

EXP(value)

LN(value)

Returns the square root of value. Value must not be
negative, or else a Bad Result error will occur.

Returns value to the power of power. This is the same
as the “^” operator.

Returns the base-10 logarithm of value. LOG10(5) result: 0.7

Returns e (2.72) raised to the power of value. EXP(1) result: 2.72

Returns natural logarithm of value. LN(1) result: 0

Table 2-12 - Extended Logarithmic Functions

2.4.4 Trigonometry Functions

Function Description Examples

DEG(value)

RAD(value)

SIN(value)

COS(value)

TAN(value)

ASIN(value)

ACON(value)

ATAN(value)

SINR(value)

COSR(value)

Converts value from radians to degrees. DEG(1) result: 57.3

Converts value from degrees to radians RAD(57.3) result: 1

Returns the sine of value. SIN(90) result: 1

Returns the cosine of value. COS(90) result: 0

Returns the tangent of value. TAN(0) result: 0

Returns the arcsine of value. Value must be con-
strained to between -1 and 1, otherwise a Bad Result
math error will occur.

Returns the arccosine of value. Value must be con-
strained to between -1 and 1, otherwise a Bad Result
math error will occur.

Returns the arctangent of value. ATAN(0.5) result: 26.6

Same as the SIN function, except value is assumed to
be radians.

Same as the COS function, except value is assumed to
be radians.

SQRT(4) result: 2
SQRT(77) result: 8.77
SQRT(-4) result: ERROR
SQRT(ABS(-4)) result: 2

POWER(2,3) result: 8
POWER(-7,2) result: 49

LOG10(1) result: 0
LOG10(100) result: 2

EXP(0.5) result: 1.65

LN(2.72) result: 1.0
LN(7) result: 1.95

DEG(PI) result: 180

RAD(180) result: 3.14

SIN(270) result: -1
SIN(0) result: 0

COS(270) result: -1
COS(0) result: 1

TAN(270) result: 1.8E+07 (very high
number, to simulate infin ity)

ASIN(0.5) result: 30
ASIN(1.01) result: EROR

ACOS(0.5) result: 60
ACOS(1.01) result: ERROR

ATAN(1) result: 45
SINR(PI) result: 0

SINR(1) result: 0.84
COSR(PI) result: -1

COSR(1) result: 0.54

Table 2-13 - Extended Trigonometry Functions

2-10 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

Function Description Examples

TANR(value)

ASINR(value)

ACOSR(value)

ATANR(value)

Same as the T AN function, except value is assumed to
be radians.

Same as the ASIN function, except value is assumed
to be radians. Value must be constrained to between -1
and 1, otherwise a Bad Result math error will occur.

Same as the ACOS function, except value is assumed
to be radians. Value must be constrained to between -1
and 1, otherwise a Bad Result math error will occur.

Same as the ATAN function, except value is assumed
to be radians.

TANR(PI) result: 0
TANR(1) result: 1.56

ASINR(PI) result: ERROR
ASINR(1) result: 1.57

ACOSR(PI) result: ERROR
ACOSR(1) result: 0

ATANR(PI) result: 1.26
ATANR(1) result: 0.79

Table 2-13

- Extended Trigonometry Functions

2.4.5 Analog Change Detection

Function Description Examples

CHANGE(analog input, change

delta)

Returns a 1 when the analog input has changed values
greater then the change delta, since the last run.

Table 2-14 - Analog Change Detection

2.4.6 Unit Conversion and Temperature Functions

Function Description Examples

EUC(value, type)

P2T(pressure, refrigerant)

T2P(temperature, refrigerant)

ENTHALPY(temp,hum)

DEWPT(temp,hum)

WETBULB(temp,hum)

APPTEMP(temp,hum)

Converts the value of value from its engineering unit,
designated by type, to its equivalent SI unit. Refer to

Table 2-2 for a list of unit types, suffixes, and their

equivalent SI units.
Used for refrigeration and HVAC. Converts pressure

to the corresponding temperature based on the chosen
refrigerant. This function accep ts the following values
for refrigerant : R502, R22, R401A, R401B, R402A,
R402B, R408A, R134A, R404A, R507, and R717.

Used for refrigeration and HVAC. Converts tempera-

ture to the corresponding pressure based on the chosen
refrigerant. This function accepts the following values

for refrigerant : R502, R22, R401A, R401B, R402A,
R402B, R408A, R134A, R404A, R507, and R717.

Returns enthalpy for the given temperature temp and
relative humidity hum.

Returns the dewpoint for the given temperature temp
and relative humidity hum.

Returns the wet bulb temperature for the given tem­perature temp and relative humidity hum.

Returns the apparent temperature for the given tem­perature temp and relative humidity hum.

CHANGE (AI1, 1DDF)
If the current AI1 value > (is greater
than) the previous AI1 + 1DDF, or the
current AI1 value < (is less than) the
previous AI1 - 1DDF, the result is 1.0

EUC(212,DF) result: 100 (converts
212°F to 100°C)

P2T(100PSI,R22) result: 15.1 DC (59.1
DF)
P2T(6BAR,R404A) result: 4.9 DC (40.8
DF)

T2P(15.1DC,R22) result: 100 PSI
T2P(40.8DF,R404A) result: 6 BAR

ENTHALPY(78DF,50) result: 86.3
BTU/Lb

DEWPT(78DF,50) result: 58.3 DF

WETBULB(78DF,50) result: 65.1 DF

APPTEMP(78DF,50) result: 78.5 DF

Table 2-15 - Conversion and Temperature Fun ctions

Functions Functions • 2-11

2.4.7 Extended Digital Functions

Function Description Examples

BOTHEDGE(input)

Returns 1.0 when the digital input, digital output, or
alarm output has transitioned either from OFF to ON
or ON to OFF . When used as an equation for a one­shot output, the result will be an ON (1.0) pulse for an
amount of time determined by the PW equation (see

Section 1.4.4, Pulse Width Equations).

INVEDGE(input)

EDGE(input)

Returns 1.0 when the digital input, digital output, or
alarm output has transitioned from ON to OFF. When
used as an equation for a one-shot output, the result
will be an ON (1.0) pulse for an amount of time deter­mined by the PW equation (see Section 1.4.4, Pulse
Width Equations).

Returns 1.0 when the digital input, digital output, or
alarm output has transitioned from OFF to ON. When
used as an equation for a one-shot output, the result
will be an ON (1.0) pulse for an amount of time deter­mined by the PW equation (see Section 1.4.4, Pulse
Width Equations).

Table 2-16 - Extended Logarithmic Functions

2.4.8 Time and Date Functions

BOTHEDGE(DI3)

INVEDGE(DI3)

EDGE(DI3)

Function Description Examples

NEWMINUTE()

NEWHOUR()

NEWDAY()

NEWMONTH()

Returns a 1.0 if the minute has changed since the last
time the algorithm has been run. Otherwise, it returns
a zero. The result is a short ON transition about once
per minute. Parenthesis accepts no arguments, but
empty parenthesis must still be placed at the end of
this function name in the equation.

Returns a 1.0 if the hour has changed since the last
time the algorithm has been run. Otherwise, it returns
a zero. The result is a short ON transition once per
hour on or about the top of the hour. Parenthesis
accepts no arguments, but empty parenthesis must still
be placed at the end of this function name in the equa­tion.

Returns a 1.0 if the day has changed since the last time
the algorithm has been run. Otherwise, it returns a
zero. The result is a short ON transition once per day
on or around midnight. Parenthesis accepts no argu­ments, but empty parenthesis must still be placed at
the end of this function name in the equation.

Returns a 1.0 if the month has changed since the last
time the algorithm has been run. Otherwise, it returns
a 0.0. The result is a short ON transition once per
month at 12 midnight on day 1 of each month. Paren­thesis accepts no arguments, but empty parenthesis
must still be placed at the end of this function name in
the equation.

NEWMINUTE() result: ON transition
once per minute.
NEWMINUTE result: ERROR (no
parenthesis)

NEWHOUR() result: ON transition
once per hour.
NEWHOUR result: ERROR (no paren­thesis)

NEWDAY() result: ON transition once
per day.
NEWDA Y result: ERROR (no parenthe­sis)

NEWMONTH() result: ON transition
once per month.
NEWMONTH result: ERROR (no
parenthesis)

Table 2-17 - Time and Date Functions

2-12 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

Function Description Examples

NEWYEAR()

TIME()

MINUTE()

HOUR()

DAY()

MONTH()

YEAR()

ISLEAP()

ISDST()

DAYOFWEEK()

Returns a 1.0 if the year has changed since the last
time the algorithm has been run. Otherwise, it returns
a 0.0. The result is a short ON transition once per year
at 12 midnight on January 1st. Parenthesis accepts no
arguments, but empty parenthesis must still be placed
at the end of this function name in the equation.

Returns the current time in the number of seconds
since midnight. Parenthesis accepts no arguments, but
empty parenthesis must still be placed at the end of
this function name in the equation.

Returns the minute portion of the current time. Paren­thesis accepts no arguments, but empty parenthesis
must still be placed at the end of this function name in
the equation.

Returns the hour portion of the current time in 24-hour
format. Parenthesis accepts no arguments, but empty
parenthesis must still be placed at the end of this func­tion name in the equation.

Returns the day of the month. Parenthesis accepts no
arguments, but empty parenthesis must still be placed
at the end of this function name in the equation.

Returns a number from 1-12 representing the month of
the year. Parenthesis accepts no arguments, but empty
parenthesis must still be placed at the end of this func­tion name in the equation.

Returns the current year in four-digit format. Paren­thesis accepts no arguments, but empty parenthesis
must still be placed at the end of this function name in
the equation.

If the current year is a leap year, returns a 1.0. Other­wise, returns 0.0. Parenthesis accepts no arguments,
but empty parenthesis must still be placed at the end of
this function name in the equation.

If daylight savings time is active, returns a 1.0. Other­wise, returns 0.0. Parenthesis accepts no arguments,
but empty parenthesis must still be placed at the end of
this function name in the equation.

Returns a number from 1-7 based on the current day of
the week from Sunday (1) to Saturday (7). Parenthesis
accepts no arguments, but empty parenthesis must still
be placed at the end of this function name in the equa­tion.

NEWYEAR() result: ON transition once
per year
NEWYEAR result: ERROR (no paren­thesis)

TIME() at 00:01:00 result: 60
TIME() at 06:45:00 result: 24300
TIME result: ERROR (no parenthesis)

MINUTE() at 00:14:00 result: 14
MINUTE() at 12:00:00 result: 0
MINUTE result: ERROR (no parenthe­sis)

HOUR() at 00:14:00 result: 0
HOUR() at 14:00:00 result: 14
HOUR result: ERROR (no parenthesis)

DAY() on 01/07/2005 result: 7
DAY() on 02/28/1985 result: 28
DAY result: ERROR (no parenthesis)

MONTH() on 01/07/2005 result: 1
MONTH() on 09/07/1974 result: 7
MONTH result: ERROR (no parenthe­sis)

YEAR() on 01/07/2005 result: 2005
YEAR result: ERROR (no parenthesis)

ISLEAP() on 01/07/2005 result: 0.0
ISLEAP() on 01/01/2008 result: 1.0

ISDST() on 01/07/2005 result: 0.0
ISDST() on 07/04/2005 result: 1.0

DAYOFWEEK() on 01/07/2005 result:

6.0 (Friday)
DAYOFWEEK() on 07/04/2005 result:

2.0 (Monday)

Table 2-17

- Time and Date Functions

Functions Functions • 2-13

Function Description Examples

DAYOFYEAR()

YEARFRAC()

FIRSTRUN()

UDR()

Returns a number from 1-365 based on the current day
of the year, from Jan 1 (1) to Dec 31 (365 or 366 if a
leap year).

Returns a decimal from 0.0 to 1.0 equal to the current
DAYOFYEAR divided by the number of days in the
year.

Returns a one if the flexible combiner cell has just
been created (for example, after a reboot). It will
remain a one for one control loop. Otherwise, it will
return zero.

Returns the update rate in seconds of the flexible com­biner. This can be used by the functions to do math
based on the update rate of the cell. The update rate is
set in the "General" tab.

DA YOFYEAR() on 01/07/2005 result: 7
DAYOFYEAR() on 07/04/2005 result:
185

YEARFRAC() on 01/07/2005 result:

0.02
YEARFRAC() on 07/04/2005 result:

0.51
FIRSTRUN() immediately following an

E2 reboot result: 1

Assume the Flex Combiner’s update
rate is set to 0:0:20
UDR() result: 20

Table 2-17

- Time and Date Functions

2.4.9 IF Functions

Function Description Examples

IF(value,true,false)

Table 2-18 - IF Function

If value is non-zero, returns the value of true. If value
is zero, returns the value of false.
In this function, value, true, and false can each be sep­arate equations that include inputs, operators, and
functions.

IF(AI1>=70DF,AI2,0.0) result: AI2, if
AI1 is equal to or greater than 70DF;
otherwise, 0.
IF(VOTE(DI1:DI8),AI3,AI4) result:
AI3 if more than four of the eight DI
inputs are ON; otherwise, AI4.
IF(TIME()>64800,1.0,0.0) result: 1.0 if
current time is between 9 p.m. (64,800
seconds past midnight) and midnight
(when TIME() resets to 0 seconds past
midnight). Otherwise, 0.0.

2-14 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

3 Testing and Troubleshooting Equations

sages. If all equations are formatted in a way the Flex
Combiner application understands and the equations are
yielding valid results, the “Status” will read OK. Other­wise, if there are problems, the “Status” field will read
“Math Error.”

When the Status field reads “Math Error,” you can
check Detailed Status to learn more about which equation
is causing the error and why it is occurring. To access the
“Eq Errors” screen of Detailed Status:

Figure 3-1

will not be uncommon to experience errors when program­ming a Flexible Combiner.

errors like misspelling function names or failing to close
parenthesis. Often these sorts of errors will be noticed
immediately by the Flexible Combiner application, and
you will get an error message immediately. Other times,
errors will be due to equations being properly formed but
wrongly constructed, resulting in unexpected results and
potentially math error conditions (such as dividing by
zero).

Flexible Combiner, you must check the application status
to make sure there are no syntax errors, and you must also
test your equation to make sure it is functioning the way it
was intended.

- Troubleshooting Equations

Because building equations is a complex process, it

Sometimes, these errors will be due to typographic

For this reason, after building your equations in the

3.1 Checking for Errors

The “Status” field in the Flexible Combiner Status

screen is the first place you should look for error mes-

1. Press

2. Select “

3. Press

Figure 3-2 - Equation Errors Page

The Eq Errors screen lists the names of all equation
fields in the Flex Combiner application. When there are no
errors, all status fields in this screen should read either
“None” (for no errors) or “No Equation” (equation is
blank and therefore unused). If an equation has errors, its
status field will display an error message. T able 3-1 shows
the error messages and what they mean.

 to bring up the Actions Menu.

 - Detailed Status.”

 twice to scroll over to the Eq Errors

screen.

Message Description Resolution

No Buffer There is not enough memory in E2 to parse the

equation.

Table 3-1 - Equation Errors

Checking for Errors Checking for Errors • 3-1

This shouldn’t happen unless there is a major problem with E2
memory, either due to a software issue or other type of system
failure. Contact Emerson Retail Solutions technical support if
you receive this error message.

Message Description Resolution

Mismatch() Mismatched parenthesis Verify that each open parenthesis “(“ has a corresponding

close parenthesis.
Example: ((AI3+7)*2 should be ((AI3+7)*2).

Missing() A function that requires arguments in parenthesis

does not have parenthesis.

Missing Arg A function does not have enough arguments. Verify the function has all the arguments they require, and that

Bad Type A function name or operator is incorrectly used or

spelled, or a type mismatch or typographical error
has occurred in one or more arguments.

Bad Syntax A function has too many arguments, or there is

some other problem with the equation formatting.

Divide by 0 Based on the current values of all inputs used in

this equation, a number is being divided by zero,
thus giving an invalid result.

Verify if a function needs parenthesi s that th ey are presen t and
correctly paired: for example, SIN(PI) is correct, not SIN PI
or SIN (PI. This will also occur if you used a function that
requires no arguments and did not include the parenthesis:
TIME() is correct, not TIME.

each argument is separated by a comma. CUTIN-
OUT(AI1,60,100) will return a Missing Arg er ror (no between
argument).

Check the equation carefully and make sure all input and out­put variable names and function names are spelled correctly.
Bad T ype can also occur when a type suffix is misspelled:
AI1+38F is a Bad T ype er ror because there is no F type suffix
(AI1+38DDF is correct).
This can also be caused by incorrect operators: DI1&DI7 is
wrong; DI1&&DI7 is correct.

Check the arguments for each function and make sure the re
are exactly the number required, separated by commas and
properly closed in parenthesis. If using a function that takes no
arguments, verify the parenthesis after the function name have
nothing between them: NEWMINUTE(TIME()) is incorrect;
NEWMINUTE() is correct.

This might occur if you are using an input as a divisor. For
example, DI1/DI2 would be just fine as long as DI2 is ON
(1.0); however, when DI2 is 0.0, the result is DI1/0.0, which is
invalid. Avo id creating equations that use inputs as diviso rs.

Bad Result Based on the current values of all inputs used in

this equation, the result is not a real number.

Bad Value A value passed to a function is incorrect for that

function.

Table 3-1

- Equation Errors

3.1.1 Equation Troubleshooting
Tips

This might occur if using an input in a function that, depend­ing upon the value of the input, yields an imaginary number.
SQRT(AI1) would be a Bad Result error when AI1 is negative
because the result is an imaginary number; also ASIN(AI2)
would give a Bad Result error if AI2 was greater than 1 or less
than -1.

If using inputs as arguments, verify the values being passed
from these inputs are valid values the function can use as argu­ments.

to the outputs.

• On the Flex Combiner Status screen, highlight the

input value with the arrow keys.

Test Your Equations

Especially if an equation you are using is complex,
validate the equation is working as you intended it by con­trolling the input values being fed into the equation.

The easiest way to do that is to override inputs from
the Flex Combiner Status screen and watch what happens

3-2 • E2 User’s Manual Supplement: Flexible Combiner 026-1620 Rev 3 06-JAN-2011

•Press , then select “ - Override.”

Figure 3-3

blue background to signify override. The outputs whose
equations use the overridden input’s value should also
change to reflect the new value. Verify the output value is
correct for the chosen input value, and repeat as many
times as necessary to insure the equation will work cor­rectly for every possible value of the input.

Find Errors By Reducing Complex Equations

IF(AND(DI1||(AND(DI4:DI8)),DI2)=TRUE,AND(DI1,
DI2),OR(DI1,DI2))

for reasons that are not very easy to understand. The easi­est way to determine the problem would be to isolate cer­tain operators and functions, enter them separately, and see
if they parse correctly.

place would be the test argument in the IF statement:

alone should yield a zero or non-zero value. If there is an
error here, there would likewise be an error in the whole
equation. In fact, when this equation is entered by itself, it

- Override Screen

• In the “In Override” field, press

• In the Override Time field, enter the amount of time
you want the override to last in H:MM:SS format.
If you want an indefinite override, enter 0:00:00.

• Enter the desired value for override in the “Over­ride Value” field (a number if analog, a digital state
(ON or OFF) if digital).

•Press

The overridden input’s value should appear with a light

Consider this complex equation for a digital output:

As written, this equation will return a Bad Type error,

In the case of the example equation, a good starting

AND(DI1||(AND(DI4:DI8)),DI2)=TRUE

For the IF statement to work correctly, this equation

 to begin the override and return to the

Status Screen.

 to select Yes.

yields a “Bad Type” error. It still isn’t quite obvious why
the error occurs, so the next step is to reduce it further.

Because the “=” operator requires two valid values to

compare, the expression
AND(DI1||(AND(DI4:DI8)),DI2) if formatted correctly
should result in some value that can be compared to
TRUE. Entering this expression by itself in the equation
field, however, causes a “Missing Arg” error. This means
one or more functions in this expression are missing a
valid argument they need. Because of this, the expression
AND(DI1||(AND(DI4:DI8)),DI2) did not yield a valid
value that could be compared to TRUE using the “=” oper­ator; this is why the error in the full equation was a “Bad
Type” error.

To find the bad or missing argument, you can analyze
each operator and function starting with the smallest com­ponent and working up:

AND(DI4:DI8) is correctly formatted and gives no
errors, since the AND function accepts a range of digital
inputs.

DI1||(AND(DI4:DI8)) also correct, since both DI1 and
AND(DI4:DI8) are valid values that can be operated on by
the “||” operator.

By process of elimination, then, the problem with
AND(DI||(AND(DI4:DI8)),DI2) is the first AND func­tion. The AND function as per the description accepts only
multiple values, separated by commas, or ranges separated
by a colon. The argument DI1||(AND(DI4:DI8)) incor-
rectly uses an operator “||” which is not allowable in a
range argument. Therefore, this expression is wrong and
must be formatted in some other way that achieves the
same result. A valid alternative would be to use the opera­tor “&&” instead of an AND function:

DI1||(AND(DI4:DI8))&&DI2

Entering this expression by itself in the equation field
yields no errors. With the error resolved, you can enter the
corrected full equation and recheck the result:

IF(DI1||(AND(DI4:DI8))&&DI2=TRUE,AND(DI1,
DI2),OR(DI1,DI2))

This equation parses correctly with no errors.

Checking for Errors Checking for Errors • 3-3

Appendix

When an alarm output is set up (AL1 - AL4), the text that will appear in the Alarm Log can be configured (Section

1.7, Alarms). A complete list of the available alarm text appears below:

• Trip Alarm

• Last On Time Expired

• Last Off Time Expired

•# of Events

• Events Per Hour

•Total On Time

• Occupied High Limit

• Occupied Low Limit

• Unoccupied High Limit

• Unoccupied Low Limit

• Gradual Change Limit

• High Limit Alarm

• Low Limit Alarm

• Alarm Limit Exceeded

• Normal High Limit

• Normal High Limit

• Alternate High Limit

• Alternate Low Limit

• Comb Temp High Limit

• Did Not Term. Defrost

•Product Temp Hi Limit

• Product Temp Lo Limit

• Differential Limit

• KW Demand Limit

• FreezeStat is too low

• Smoke Detected

• Dirty Filter Detected

•Door Open

•VS Alarm

• Comb Temp Low Limit

• Case Temp High Limit

• Case Temp Low Limit

• Curtail On

• Discharge Trip

• High Discharge Limit

• High Suction Limit

• Low Suction Limit

• Proof Fail

• All Lights On

• HVAC Shutdown

• REFR Shutdown

• HVAC Phase Loss

• REFR Phase Loss

• A-1