Module spare parts TPMC815-11

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Product Description

Product Description
Focus on DCS, PLC, robot control system and large servo system.
Main products: various modules / cards, controllers, touch screens, servo drivers.
Advantages: supply of imported original products, professional production parts,
Fast delivery, accurate delivery time,
The main brands include ABB Bailey, Ge / fuanc, Foxboro, Invensys Triconex, Bently, A-B Rockwell, Emerson, ovation, Motorola, xyvom, Honeywell, Rexroth, KUKA, Ni, Deif, Yokogawa, Woodward, Ryan, Schneider, Yaskawa, Moog, prosoft and other brands
TPMC815-11
The most common effect of phase nonlinearity is ringing in response to a step input. As Figure 4-8 shows, the SCXI-1141 elliptic filter exhibits the most overshoot and ringing and the SCXI-1142 Bessel filter has no overshoot or ringing. The SCXI-1143 module Butterworth filter has a step response that is a compromise between the SCXI-1141 module and the SCXI-1142 module. The SCXI-1143 module filter has an overshoot, but it has less ringing than the SCXI-1141. You should consider the step response if the intended application is sensitive to overshoot or ringing. See Table A-1, Settling Time with Respect to Cutoff Frequency, for detailed settling specifications. Additionally, use care when selecting gain settings to assure that the input signal plus any overshoot voltage result in an output signal within the ±5 V range of the SCXI-1141/1142/1143 module. 0 0.5 1 1.5 2 –100 0 100 200 300 Bessel (1142) Butterworth (1143) Elliptic (1141) Frequency (Normalized) Phase Error (Degrees) Chapter 4 Theory of Operation © National Instruments Corporation 4-11 SCXI-1141/1142/1143 User Manual Figure 4-8. Unit Step Response of the SCXI-1141/1142/1143 Module Setting the Cutoff Frequency The cutoff frequencies of the filters in the SCXI-1141/1142/1143 module are set internally by dividing a base frequency of 100 kHz by an integer. You can determine the allowable cutoff frequencies for the SCXI-1141/1142/1143 module as follows: where n is an integer ≥ 4 and fc ≥ 10 Hz. In other words, fc = {25, 20, 16.7, 14.3, 12.5, ..., 0.01} kHz. If you are using NI software, the software automatically chooses a divisor, n, that best matches the cutoff frequency you specify and returns the actual cutoff frequency chosen. The correct cutoff frequency depends on the application. If phase nonlinearity, ringing, passband ripple, or aliasing is a concern in the application, you may need to set the cutoff frequency several times higher 0 2 4 6 8 10 0 0.2 0.4 0.6 0.8 1 1.2 1.4 Time (Seconds) Bessel (1142) Butterworth (1143) Elliptic (1141) Output Voltage (V) fc 100 n = -------- kHz Chapter 4 Theory of Operation SCXI-1141/1142/1143 User Manual 4-12 than the signal frequency range of interest. At frequencies much lower than the cutoff frequency, passband ripple and phase nonlinearity are much less noticeable. If you use the filter to prevent aliasing, you must set the cutoff frequency no higher than one-third of the frequency at which that channel is being sampled for the SCXI-1141 module, one-twelfth of the frequency for the SCXI-1142 module, or one-sixth of the frequency for the SCXI-1143 module. Using the SCXI-1141/1142/1143 Module as an Antialiasing Filter Aliasing, a phenomenon of sampled data acquisition systems, causes a high-frequency signal component to take on the identity of a low-frequency signal. Figure 4-9 shows an example of aliasing. Figure 4-9. Aliasing of an Input Signal with a Frequency 0.8 Times the Sample Rate The solid line depicts a high-frequency signal being sampled at the indicated points. However, when these points are connected to reconstruct the waveform, as shown by the dotted line, the signal appears to have a lower frequency. Any signal frequency with a frequency component greater than one-half of the sample rate is aliased and incorrectly analyzed as having a frequency below one-half of the sample rate. This limiting frequency of one-half the sample rate is known as the Nyquist frequency. To prevent aliasing, you must remove all signal components with frequencies greater than the Nyquist frequency before sampling an input signaled. After an unfiltered signal is sampled and aliasing has occurred, it is impossible to accurately reconstruct the original signal. The SCXI-1141/1142/1143 module removes these high-frequency signals before they reach a DAQ device and cause aliasing.