科爾摩根 S77202-NANANA Servostar伺服驅(qū)動(dòng)器

自PLC誕生那天起，就一直占據(jù)著整個(gè)自動(dòng)化控制系統(tǒng)的核心地位。對(duì)于PLC發(fā)展方向的討論也常常不絕于耳，無(wú)論從10年前就有人預(yù)言PAC將取代PLC，還是這段時(shí)間甚至有人說(shuō)未來(lái)工業(yè)4.0時(shí)代不再需要PLC。

那么對(duì)于當(dāng)前全球都在大力部署智能制造的轉(zhuǎn)型時(shí)期，我們需要什么樣的PLC呢？特別是被譽(yù)為“皇冠上的明珠”——中大型PLC將會(huì)有哪些特征呢？

首先，有一點(diǎn)需要明確，現(xiàn)在講的高端PLC和10年以前甚至5年以前已經(jīng)不一樣了。不是說(shuō)10年前是高端PLC，現(xiàn)在它還就還可以稱(chēng)之為高端PLC。因?yàn)樯鐣?huì)在發(fā)展，更先進(jìn)的東西出來(lái)了，所謂的高端，評(píng)判它的標(biāo)準(zhǔn)在不同的時(shí)期是不一樣的。當(dāng)根據(jù)新情況或環(huán)境變化改變行為時(shí)，系統(tǒng)具有適應(yīng)性。一個(gè)自適應(yīng)控制器是一種控制器，其可以修改響應(yīng)于該系統(tǒng)和過(guò)程干擾的動(dòng)態(tài)變化其行為。

自適應(yīng)控制概念
自適應(yīng)控制有很多定義，其中一個(gè)最被接受的是它是一種非線(xiàn)性的特殊控制系統(tǒng)，其中過(guò)程的狀態(tài)可以在以不同速度演化的兩個(gè)時(shí)間尺度上分離。  有許多類(lèi)型的控制器可以在系統(tǒng)參數(shù)發(fā)生變化時(shí)提供良好的調(diào)節(jié)特性。但是根據(jù)上面的定義，它們并不是真正的自適應(yīng)，因?yàn)樽赃m應(yīng)是在開(kāi)環(huán)中完成的。

A newly commissioned pressure control system has a problem: the controller registers a process ?uid pressure of 22 PSI, but two pressure gauges connected to the same vessel both register 35 PSI.

A technician is sent to troubleshoot this problem and decides to measure current at terminal 2 of TB-52 (located in Field Panel JB-25). The current signal registers 15.2 milliamps DC:
ased on these symptoms and inbation contained in this loop diagram, answer the following questions:Where do you think the problem lies, and what sort of problem might it be?

Sketch how the technician’s milliammeter should be connected in order to intercept the loop current at terminal 2 of TB-52. Include the test lead colors (red, black) in your answer.Identify what steps the technician (or operator) should have done prior to taking the current measurement, to ensure nothing bad (e.g. process interruption, alarms) would happen when the circuit was broken to insert the milliammeter.
Modify both the transmitter and control valve 4-20 mA loop circuits to include diodes for the purpose of the convenient current measurement.