Future Design MCTB 4.3, User Manual

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MCTB
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4.6.2.2 Square Root (SQRT) Implementation
To obtain the square root of a value or expression, you first activate the square root function by pressing the
SQRT
key. This appends the square root function “SQRT[“ to the current equation. The SQRT key will “lock”
on as indicated by changing color. All variable selections following the activation of the SQRT function will be
part of the square root expression. Pressing the SQRT key again will end the square root entry by appending
the closing bracket “]” to the equation and the key will unlock. Equation entry can then continue as normal.
4.6.2.3 Sample and Hold
To implement sample and hold, simply assign a trigger to the math equation instead of using the default
“Always” selection. When the trigger is on, sampling will occur, i.e., the equation will be continuously evaluated.
When the trigger is off, the MCTB will stop evaluating the equation, but the previous value will be maintained.
This provides a simple means for performing sample and hold.
For example, at the end of a cycle we want to capture the average temperature of loops 1 and 2 and hold that
value until the next cycle is started. The event input of loop 1 is already used as a status input to indicate that
the cycle is active, so we can it as our trigger. Our math/logic block would then be as follows:
Since the trigger is active during the cycle, the average of loop 1 and loop 2 will be calculated and displayed on
the Overview screen. When the cycle completes and the input turns off, the trigger for the equation will also
turn off. The average of loop 1 and loop 2 will no longer be calculated; however, the previous value calculated
will be held and displayed on the Overview screen until the next cycle is started, at which the trigger is again
activated when the input turns on and a new average is calculated.
4.6.2.4 Basic Logic Operators
The MCTB provides standard logic operators (AND, OR, NOT) as well comparison operators of less than (<),
greater than (>) and equals (=). Couples with the free-form entry of the MCTB math/logic blocks, it permits the
operators to be used in any combination with any available system variable to create the custom logic required
for any application.