Abelko IMSE WebMaster Pro - Page 107

15
101
15 - Graphical programming
Next, create ve inputs – two channels, two parameters and one calendar. Start by
clicking on the square in the top left, select the input called "Sunpanel roof" and
click Add Input. Click on the square underneath and insert "Accumulator bottom".
Click on the next square down. Change the upper list box to PARAMETER, select
"Di.temp.Sunpanel" and add it. Move to the next square down and insert "Hys-
teresis Sunpanel". Finally, change the upper list box to CALENDAR and add "Pump
exercise" to the fth square.
We start by adding the storage tank temperature and the dierential temperature.
We then subtract the hysteresis from the total. We now have two temperatures.
One is the storage tank temperature + the dierential temperature. The other is
the storage tank temperature + the dierential temperature - the hysteresis. Fol-
low these steps: Click on the square to the right of "Accumulator bottom". Select
the + (plus) operator and add it.
Select the square to the right on the next row down and add the - (minus) opera-
tor. Connect "Accumulator bottom" and "Di.temp" to their respective inputs in
the add operator, and connect the output from this operator to the + input of the
subtract operator. Connect "Hysteresis" to the – input of the subtract operator.
Now we need to compare these two temperatures with the
solar collector temperature. Remember we want to start the
pump when the solar collector temperature is higher than the
storage tank temperature + the dierential temperature, and
to stop it when the solar collector temperature is lower than
the storage tank temperature + the dierential temperature
- the hysteresis. We need two operators to implement this
condition. Click on the fourth square in the top row and add
the > (greater than) operator, and add the < (less than) to the
square to the right of the subtract operator. Connect the solar
collector temperature to the upper input of these two opera-
tors. (You will need to draw two connections, from output to
input.) Now connect the output from the add operator to the
lower input of the operator on top, and connect the output
from the subtract operator to the lower input of the operator
underneath.
You now have two outputs implementing the condition above. The upper output is on when the
solar collector temperature is higher than the accumulator tank temperature + the dierential tem-
perature. The other output is on when the solar collector temperature is lower than the accumulator
tank temperature + the dierential temperature - the hysteresis.