Programmable logic controller (PLC) programmable filter

Abstract

The invention discloses a programmable logic controller (PLC) programmable filter. The PLC programmable filter comprises a digital integration device (10), a threshold comparison device (20) and a positive and negative saturation comparison device (30), wherein the threshold comparison device (20) and the positive and negative saturation comparison device (30) are connected with the digital integration device (10). The PLC programmable filter further comprises a parameter writing device (40) which is respectively connected with the digital integration device (10), the threshold comparison device (20) and the positive and negative saturation comparison device (30). The PLC programmable filter has the advantages that a preset positive saturation value and a negative saturation value and a preset high level threshold and a low level threshold can be separately independently arranged, a preset positive integral constant and a negative integral constant can be independently programmably set, so that a very flexible filtering function is achieved, and monopulse and continuous pulse effect separation and high level and low level filtering effect separation can be achieved.

Description

technical field [0001] The invention relates to the field of PLC filtering, in particular to a PLC programmable filter. Background technique [0002] At present, many programmable logic controllers (Programmable Logic Controller, PLC) use hardware filtering, such as RC, LC and other filtering technologies. However, because the parameters of hardware filters are determined, once formed, they cannot be changed during use, making PLC input The port is either a high-speed input or a low-speed input, so it is not conducive to the repeated use of PLC input and cannot be used in flexible occasions. [0003] There are also some digital software filters in the prior art, and the two-way counters that use digital software filters usually have only one judgment threshold, that is, the counter uses a comparator to realize the threshold judgment input high and low levels, so that the interference signals generated near the threshold are the same It can lead to misoperation; even if two ...

AI Technical Summary

Problems solved by technology

[0002] At present, many programmable logic controllers (Programmable Logic Controller, PLC) use hardware filtering, such as RC, LC and other filtering technologies. However, because the parameters of hardware filters are determined, once formed, they cannot be changed during use, making PLC input The port is either a high-speed input or a low-speed input, so it is not conducive to the repeated use of PLC input and cannot be used in flexible occasions

[0003] There are also some digital software filters in the prior art, and the two-way counters that use digital software filters usually have only one judgment threshold, that is, the counter uses a comparator to realize the threshold judgment input high and low levels, so that the interference signals generated near the threshold are the same It can lead to misoperation; even if two thresholds are used as judgments, due to its own limitations, after setting the threshold and the positive and negative values ​​of the integral constant, these parameters can no longer be modified, and the positive value of the integral constant is the same as the integral The absolute value of the negative value of the constant is the same value, so the filter width and hysteresis cannot be adjusted according to different inputs, and different filter effects cannot be satisfied for special applications.

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