Custom Strategy Example - Danfoss AK2-SC 255 Reference Manual

Custom strategy
example
Creating the
miscellaneous points
Sensor inputs
RS.8D.M1.22
Data definitions area
Rules area
Let's create a point now. Afterwards we will discuss each area and field in detail. It is
important to plan the strategy first.
We want to control a compressor room exhaust fan. We want the fan to run when-
ever the compressor room temperature is 90°F or higher; we also want it to run in
case of a refrigerant leak of 500 ppm or more. So let's list the types and values we
will need:
OI calculated point
SI °F misc SI
Num
SI ppm misc SI
Num
RO
[Note: the leak sensor may not need to be configured as a miscellaneous sensor if
there is a standard leak detector configured. Instead, we will just select SI ppm as the
sensor type and then pick the sensor from the list that appears under data definitions.]
It is important to understand that only the OI will be created in the calculated points
screen. The state of the OI will depend on the evaluation, at any time, of the logical
statements that we are going to write. The other points (the RO and the two SIs) will
be created as miscellaneous points.
Now we will create the first of the sensor inputs we will need, that for the leak
detector. Exit to the Configure Miscellaneous menu and select Sensor Inputs.
The configuration is straightforward for both of the sensors we need:
AK2-SC 255 Reference Manual
Units
Style
Undo (button)
Cancel (button)
This area contains information that identifies points that
will be used in the logical statements in the next area,
and the current value of each. The area by default has
lines for two definitions, but it can be enlarged by
selecting the horizontal divider line between it and the
next field, pressing ENTER, and then selecting Insert
from a popup box. You will see this done in a few
pages during the presentation of our first example.
This is the area that will contain the logical statements
that determine whether the point is on or off (OI) or
the value (SI) that is used. At the bottom of the area is
the current value of the result.
to control the RO
compressor room temperature
90 (the temperature setpoint)
leak detector sensor [see note]
500 (the leak ppm level)
to control the fan
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