Setting the integral threshold
thld
The integral threshold value corresponds in general to a process property, which is simple to determine (e.g. the content of a tank).
The function block can also be used for the integral calculation of smaller input values, as well as when the result of the integral invoice is very large. In this case there is the risk that the integral values will become so strongly reduced in relation to the total values that they will no longer be considered. The solution offered by TOTALIZER is in the limit of the collective index OUT on the threshold value thld, so that the integral value is never insignificant in relation to the partial collective index. The result of the integral total (outc) is also calculated: the controller saves the frequency of achieving the threshold value thld on the collective index OUT.
When the threshold value thld corresponds to the value 0, the integral value will not be calculated, the outputs remain blocked.
As soon as the output OUT exceeds the threshold value thld, the output done is set to 1. During the execution of the function block they are set to zero again.
When the counter cter achieves its maximum value (65535), this counter no longer changes. The outputs OUT continues to function when the threshold value thld is included. However, the output outc and the counter cter can no longer be used.
Negative values of the input IN are never considered, because they always lie below the division cutoff.
Timing diagram of the TOTALIZER block
There are 3 individual operating modes for the TOTALIZER function block: Tracking, Reset and Halt:
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Operating mode
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Parameter
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Meaning
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Tracking
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TR_S = 1
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The parameter TR_I will be run on outc and the parameter OUT and cter will be set so that the following equation applies:
outc = thld x cter + OUT.
The tracking mode enables renewed synchronization of the controller outputs with the control process (e.g. as a consequence of a sensor failure).
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Reset
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rst = 1
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The outputs OUT, outc, cter and done are set to zero.
The reset via rst allows a new start from the zero reference point (for example after phase change in production).
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Halt
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hold = 1
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Integration is paused. The outputs keep their previous values.
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NOTE: By simultaneous activation of the inputs TR_S, rst and hold, the tracking mode has priority over the other operating modes and the reset operating mode has priority over halt.
Reverse integral summation (
inc_dec = 1)
Display of the function principle
In tracking mode (TR_S = 1) the parameter TR_I will be run on outc and the parameter OUT and cter will be set so that the following equation applies:
outc = thld x cter + (thld - OUT).
outc is calculated using the following formula: outc = thld x cter + (thld - OUT)
Function principle of the reverse of the integral summation
The following function principle applies:
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Step
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Action
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1
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At the first execution or positive on edge on rst the output OUT will be initiated by thld.
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2
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Thereafter with each execution the output OUT is calculated with the following formula:
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3
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As soon as the output OUT becomes negative, the following happens:
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