Danfoss AK-SM 720 Design guide
User Guide
AK-SM 720 — Boolean logic
ADAP-KOOL® Refrigeration control systems
Application
The function is contained in System manager type AK-SM 720 and
can be used for user-dened functions.
The functions can be dened on the basis of the given inputs and
outputs, and are limited by the number of the aforementioned
inputs and outputs and the grid size.
The user denes the function required. The user must be suciently familiar with Boolean logic. Danfoss cannot be held liable
for the set-up of the functions.
The logic can be constructed using signals from the following:
- Direct inputs
• 4 Pressure inputs (AI)
• 4 Temperature inputs (AI)
• 2 Voltage inputs (AI)
• 32 Digital inputs (DI)
- Selected application functions
• e.g. day/night control, defrosting, light control, etc.
- Internal variables
• 8 Constants
• 16 Temporary variables
The logic can activate the following signals:
- Direct outputs
• 2 Analogue outputs (AO)
• 32 Relay outputs (DO)
- Selected application settings
Grid size:
- 20 x 20 elds
Note!
The total number of outputs and Inputs which can be connected
to a AK-SM 720 is 80 pcs.
See AK-SM 720 manual for further details.
Content
Application ......................................................................................................... 2
Function units .................................................................................................... 3
Conguration ..................................................................................................... 4
Examples ............................................................................................................. 6
2 User guide RC8CA202 © Danfoss 02/2009 AK-SM 720 — Boolean logic
Function units
2
1
3
a
b
c
d
e
f
g
h
i
j
k
l
Depending on the type, a function unit can:
• Read an input value
• Perform a calculation
• Forward a value
• Save a set (constant) value
• Save a temporary value
• Activate an output
Contact points
A function unit may have several contact points, which function as
inputs and outputs depending on the type.
Signal path
The individual function units are assembled to form a collective
function in a grid. Each function unit is executed one by one. Reading takes place from left to right and then down. (The program
runs through a complete line before it continues onto the next
line.)
Inputs
Input signal
E.g. a temperature on an input, a digital signal or the
signal from a function.
Internal variable where a temporary calculation can be
used. (Boolean or oating point value)
Internal constant (Boolean or oating point value)
Examples
Inputs Input
A
B
Output
C
Mathematical calculations
Addition
C = A + B
Subtraction
C = A - B
Division
C = A / B
Output
A
B
Output
Output
E.g. a function, a voltage signal or a relay
Internal variable where a temporary calculation can be
saved. (Boolean or oating point value)
Logical calculations
And
C = A AND B
OR
C = A OR B
NOT
B = NOT A
DELAY
Delays a “TRUE” signal for a number of seconds.
The delay period starts every time the input becomes
”TRUE”.
The input must be ”TRUE” throughout the entire delay
period in order for the output to become ”TRUE”.
Multiplication
C = A x B
Greater than
If A > B then C = TRUE, else C = FALSE
Greater than or equal to
If A >= B then C = TRUE, else C = FALSE
Min.
The smaller value of two input values is reproduced on
the output
If A > B then C = B, else C = A
Max.
The larger value of two input values is reproduced on
the output
If A > B then C = A, else C = B
Avg.
The average of two input values is reproduced on the
output.
C = ( A + B) /2
AK-SM 720 — Boolean logic User guide RC8CA202 © Danfoss 02/2009 3
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