Future Design MCTB 4.3, Руководство пользователя

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MCTB
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When the temperature percentage of output is less than -50, event output 4 of loop 1 will activate. When the
percentage of output is above -50, the output will turn off. The two equations now provide the boost heat and
cool functions required. However, what happens if the percentage of output is varying around the desired set
point. If the heating output is varying between 79% and 81% for example, this can cause the boost heat output
to constantly turn on and off. This could cause a control issue since the second stage of heat would by cycling
on and off which may cause oscillation in temperature when the set point is first reached.
In order to prevent that, we could add delays that require the percentage of output for to exceed the required
activation point for a period of time. This would prevent the output from cycling on and off when the heating
output varies from 79% to 81% by requiring it to be above 80 for a period of 10 seconds for example. In order
to do this, we need to implement a Timer equation. To do this, we first need to increase the number of
Math/Logic equation on the Control Setup screen. Do this by setting the number of equations to 3. Next,
navigate to the Math/Logic Configuration screen and select equation 3.
Set the Type of equation to “Timer”. The Trigger can be left at the default of “Always” so that the timer is
activated/deactivated based on the percent
age of output. For the Tagname, enter “Heat Delay” to describe the
function of the timer. Next, enter the required delay period in seconds (10 for this example). The timer is
activated based on the result of the equation entered. Like the previous logic equation for boost heat, we want
the timer to activate when the percentage of output is greater than 80%. Thus, for the equation, enter
“S1_%Out>80”.
This will result in the time delay being started when the percentage of output is greater than 80%. If at any time
the percentage of output falls below 80%, the time will be reset and the delay will start again when the output
exceeds 80%. If the output remains above 80% for the 10 second delay period, the internal timer output will
be activated. To implement the delay on the output, we must now change the equation for the boost heat
output. Do this by pressing the “Next” navigation arrow at the top right of the screen to access Math/Logic 1
equation.
To use the timer in the equation, touch the equat
ion to edit it. Press the “Clear” button to delete the current
equation, and then select the timer from the logic item drop-
down menu. It will be displayed as “T3 (Heat
Delay)”. Press the “Done” button to complete the modification. You should now have Math/Logic 1 and
Math/Logic 3 equations as depicted below.
With the above two equations, the timer will begin counting down when the heat percentage of output is greater
than 80. Once the 10 second delay period expires, the internal timer output will be on. When the timer output
is on, equation one will be evaluated as true since the timer (T3) is expired. This results in event output 3 of
loop 1 activating and enabling boost heat. The same thing can be accomplished with boost cool by using a
fourth math equation to create another timer to delay the boost cool output.