使用更新的有線接口穩(wěn)定關(guān)鍵工業(yè)物聯(lián)網(wǎng)連接

　　物聯(lián)網(wǎng)產(chǎn)業(yè)（IIoT）意味著有更多的傳感器，傳感器和執(zhí)行器，需要連接。雖然無線鏈路似乎是簡(jiǎn)單的連接解決方案，他們受到安全問題，較高的初始成本，以及在工業(yè)環(huán)境中的RF傳播的不確定性。

　　相反，許多應(yīng)用程序都使用傳統(tǒng)的但更好的服務(wù)更好的基于RS-232、RS-422和RS-485協(xié)議，RS - 423收發(fā)器。這些可以幫助設(shè)計(jì)人員優(yōu)化系統(tǒng)的可靠性，信號(hào)完整性和成本效益。通過這些有線鏈路收集的匯總數(shù)據(jù)，然后可以通過一個(gè)強(qiáng)大的有線或無線連接到后端網(wǎng)絡(luò)和互聯(lián)網(wǎng)連接。

　　然而，有一些新的要求被放在這些既定的和成功的有線標(biāo)準(zhǔn)，超越他們?cè)瓉淼囊蟆８叩男诺烙?jì)數(shù)和密度，以及更快的數(shù)據(jù)速率，是具有挑戰(zhàn)性的設(shè)計(jì)師制定滿意的解決方案，網(wǎng)格與新的任務(wù)，涵蓋ESD（靜電放電），低電壓操作和容錯(cuò)要求。

　　What is RS-232 and its related standards？

　　Recommended Standard 232 （RS-232） was released by the Electronic Industries Association （EIA） in 1962. Its original role was to connect computers to electromechanical teletypewriters （often called “Telex” machines）， modems， and printers， but the standard was soon adopted for many other interface applications.

　　RS-232 is a relatively simple standard and is limited to point-to-point serial links with a single sender and receiver. It can be used for simplex， half-duplex， and full-duplex links， and was limited to 19，200 baud （not necessarily the same as bits/sec， but often is）。 The most widely used revision， RS-232D， specified use of ±25 volts for the signaling of ones and zeros. Note that the standard did not specify the encoding of the data itself. It only called out the signal levels， slew rates， start/stop framing， and basic handshaking for the connection.

　　To meet the need of growing networks， the standard was extended to RS-422， RS-423， and finally RS-485， which added multi-drop capability， higher speeds， and longer distances （Table 1）.