6. Function blocks6.1 Manufacturer function blocks6.1.4.2 FT - PT1-Signal smoothing filterGeneraleasyE4 base devices provide 32 PT1 signal smoothing filter functionblocks FT01...FT32.The function block smoothes noisy signals such as analog input sig-nals. It operates as a low pass filter.Operating principleThe signal to be smoothed is added via input I1. The smoothed output value is trans-ferred to QV.EN=1 starts the function block. EN=0 initiates a reset in which the output QV is reset to0.You can use the TG input to set the recovery time. This recovery time is the time overwhich smoothing will be applied, and it should not be longer than necessary, as signalswill be delayed more than is actually necessary for smoothing. Please note that delaysare an unavoidable side effect of signal smoothing.The input KP is used to define a proportional gain factor. The input signal I1 is multipliedwith this factor. The value <100> corresponds to a KP of 1.The PT1 delayed output value is provided at output QV.If the function block is called for the first time when the device is started or after areset, this will result in the delay value being initialized with the input value (the PT1delay does not start with a value of zero). In other words, the output value at QV willequal the input value at I1 during the first processing cycle. This will speed up the PT1starting behavior.Step response of the function blockThe step response of the FT-PT1 function is an e function. After a time t = Tg the nor-malized output value is 0.63 QV/QVmax.Figure 149: Response of the FT function blockOutput value of the FT-PT1 signal smoothing filter function block, TangenteasyE4 11/18 MN050009 EN www.eaton.com 279
