PLC的機(jī)械結(jié)構(gòu)主要是外殼和底板。不僅要考慮內(nèi)部電路板、通信接口和端子的連接和固定，還要考慮PLC的散熱、防止外部灰塵、水汽和沖擊，以及對(duì)振蕩甚至電磁干擾的屏蔽。此外，結(jié)構(gòu)規(guī)劃是產(chǎn)品外觀的主要表現(xiàn)形式。因此，產(chǎn)品結(jié)構(gòu)規(guī)劃不僅需要了解各種機(jī)電知識(shí)，還需要考慮現(xiàn)場(chǎng)用戶的使用習(xí)慣，還需要有足夠的藝術(shù)修養(yǎng)。
軟件方面，從開發(fā)的角度來看，完成PLC的所有功能一直是一項(xiàng)非常龐大的系統(tǒng)工程，而其中一些工作在整個(gè)PLC系統(tǒng)的軟件規(guī)劃和編程中，原本只是全部工作量的一小部分。其他，主要圍繞可靠性方面，軟件規(guī)劃和編程。軟件可靠性規(guī)劃，首先要考慮PLC在正常運(yùn)行中可能出現(xiàn)的各種緊急情況，進(jìn)行容錯(cuò)規(guī)劃。因?yàn)镻LC直接處理各種硬件，包括CPU地址、數(shù)據(jù)、寄存器、緩存和外部輸入輸出控制，許多硬件會(huì)因各種影響而發(fā)生不同的變化。因此，內(nèi)部容錯(cuò)處理的工作量已經(jīng)很大，在編程的這些方面沒有一定的規(guī)則和先例可以遵循，這一切都取決于經(jīng)驗(yàn)。此外，還有一些外部環(huán)境影響，如電磁干擾、溫度變化、信號(hào)故障、通信故障、各種信號(hào)的超限變化，以及人為操作故障，如編程故障、接線故障和操作故障；我們必須進(jìn)行必要的容錯(cuò)規(guī)劃，這取決于經(jīng)驗(yàn)的積累。The mechanical structure of PLC is mainly shell and bottom plate. Not only the connection and fixation of internal circuit board, communication interface and terminal, but also the heat dissipation of PLC, the prevention of external dust, water vapor and impact, and the shielding of oscillation and even electromagnetic interference should be considered. In addition, structure planning is the primary manifestation of product appearance. Therefore, product structure planning not only needs to understand all kinds of electrical and mechanical knowledge, but also needs to consider the usage habits of on-site users, and also needs to have enough artistic accomplishment.

Software, from the perspective of development, to complete all the functions of PLC has been a very huge system engineering, and some of these jobs in the entire PLC system software planning and programming, originally only a small part of all the workload. Others, mostly around the reliability aspect, software planning and programming. Software reliability planning, first of all to think about PLC in normal operation of various possible emergencies, to carry out fault-tolerant planning. Because PLC directly deals with all kinds of hardware, including CPU address, data, register, cache, and external input and output control, and many hardware will have different changes due to various influences. Therefore, the internal fault-tolerant processing is already a large workload, and there are no certain rules and precedents to follow in these aspects of programming, It all depends on experience. In addition, there are some external environmental impacts, such as electromagnetic interference, temperature change, signal fault, communication fault, overrun change of all kinds of signals, and human operation faults, such as programming fault, wiring fault and operation fault; We must carry out the necessary fault-tolerant planning, which depends on the accumulation of experience.