Parameter assignment for the function block is accomplished by specifying the maximum rising velocity RATE and the limiting values OUT_MAX and OUT_MIN for the output OUT. The maximum velocity rate indicates by how much the output may change within one second.
Actual RATE = 0, becomes OUT = IN.
The limits OUT_MAX and OUT_MIN limit the upper output as well as the lower output. Hence OUT_MIN ≤ OUT ≤ OUT_MAX.
The outputs QMAX and QMIN show that the output has reached a limit or the output signal has been capped.
Two operating modes can be selected through the TR_S parameter input.
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Operating mode
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TR_S
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Meaning
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Automatic
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0
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The current value for OUT will be constantly calculated and displayed.
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Tracking
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1
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The tracking value TR_I is transferred directly to the output OUT. The control output is, however, limited by OUT_MAX and OUT_MIN.
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Explanation of the dynamic behavior of the VEL_LIM function block.
The function block follows the transition at the input IN at its maximum velocity change rate. It can also be clearly seen that the output OUT is limited by OUT_MAX and OUT_MIN with the associated QMAX and QMIN signals.
