Danfoss AK2-SC 255, Reference Manual, Page: 146 / 206

RS.8D.M1.22 AK2-SC 255 Reference Manual 145
Units
Style
Undo (button)
Cancel (button)
Data definitions area 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.
Rules area 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.
Let’s create a point now. Afterwards we will discuss each area and field in detail. It is
important to plan the strategy first.
Custom strategy
example
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 to control the RO
SI °F misc SI compressor room temperature
Num 90 (the temperature setpoint)
SI ppm misc SI leak detector sensor [see note]
Num 500 (the leak ppm level)
RO to control the fan
[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.
Creating the
miscellaneous points
Sensor inputs
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: