Uyini umqondo wesixhumi esibonakalayo se-RS485 kuqala?
Ngamafuphi, indinganiso yezimpawu zikagesi, echazwa yi-Telecommunications Industry Association kanye ne-Electronic Industries Alliance. Inethiwekhi yokuxhumana yedijithali esebenzisa leli zinga lingadlulisela amasignali ngempumelelo ebangeni elide nasezindaweni ezinomsindo ophezulu we-elekthronikhi. I-RS-485 yenza kube nokwenzeka ukumisa amanethiwekhi endawo angabizi kakhulu kanye nezixhumanisi zokuxhumana zamagatsha amaningi.
I-RS485 inezinhlobo ezimbili zezintambo: isistimu yezintambo ezimbili kanye nesistimu yezintambo ezine. Isistimu yezintambo ezine ingafinyelela kuphela ukuxhumana kwephoyinti kuya kwephuzu futhi ayivamisile ukusetshenziswa manje. Njengamanje, indlela yokuhlanganisa izintambo ezimbili isetshenziswa kakhulu.
Ebunjiniyela bamanje obubuthakathaka, ukuxhumana kwe-RS485 ngokuvamile kusebenzisa indlela yokuxhumana yesigqila, okungukuthi, umsingathi oyedwa onezigqila eziningi.
Uma unolwazi olunzulu nge-RS485, uzothola ukuthi luningi ngempela ulwazi ngaphakathi. Ngakho-ke, sizokhetha ezinye izindaba esivame ukuzicabangela kugesi obuthakathaka ukuze wonke umuntu azifunde futhi aziqonde.
RS-485 Electrical Regulations
Ngenxa yokuthuthukiswa kwe-RS-485 kusuka ku-RS-422, imithethonqubo eminingi kagesi ye-RS-485 ifana ne-RS-422. Uma ukudluliswa okulinganayo kwamukelwa, izinqamuli zokunqamula kudingeka zixhunywe entanjeni yokudlulisela. I-RS-485 ingasebenzisa izintambo ezimbili nezindlela ezine zocingo, futhi isistimu yezintambo ezimbili ingafinyelela ukuxhumana kweqiniso okunamaphuzu amaningi, njengoba kukhonjisiwe kuMfanekiso 6.
Uma usebenzisa uxhumano lwezintambo ezine, njenge-RS-422, lungafinyelela kuphela ukuxhumana kwephuzu kuya kwephuzu, okungukuthi, kungaba nedivayisi eyodwa kuphela eyinhloko kanti enye yonke imishini yesigqila. Nokho, inokuthuthuka uma iqhathaniswa ne-RS-422, futhi ingaxhuma amanye amadivayisi angu-32 ebhasini kungakhathaliseki ukuthi izintambo ezine noma indlela yokuxhuma izintambo ezimbili.
I-RS-485 yemodi evamile yokukhishwa kwamandla kagesi iphakathi kuka--7V kanye+12V, futhi ubuncane bokuvimba okokufaka kwesamukeli se-RS-485 ngu-12k;, Umshayeli we-RS-485 ungasetshenziswa kumanethiwekhi e-RS-422. I-RS-485, njenge-RS-422, inebanga eliphezulu lokudlulisela elicishe libe ngamamitha angu-1219 kanye nezinga eliphezulu lokudlulisela elingu-10Mb/s. Ubude bepheya esontekile ebhalansile buyalingana ngokuphambene nezinga lokudlulisela, futhi ubude bekhebula obukhulu obushiwo bungasetshenziswa kuphela uma isivinini singaphansi kuka-100kb/s. Izinga eliphezulu kakhulu lokudlulisela lingafinyelelwa kuphela ngebanga elifushane kakhulu. Ngokuvamile, izinga lokudlulisela eliphezulu lamapheya asontekile angamamitha ayi-100 ubude lingu-1Mb/s kuphela. I-RS-485 idinga izinqamuli ezimbili ezinenani lokumelana elilingana nesici sekhebula lokudlulisela. Lapho udlulisela ebangeni elingunxande, asikho isidingo se-resistor enqamulayo, ngokuvamile engadingeki ngaphansi kwamamitha angu-300. I-resistor enqamulayo ixhunywe kuzo zombili iziphetho zebhasi lokudlulisela.
Amaphuzu abalulekile okufakwa kwenethiwekhi ye-RS-422 ne-RS-485
I-RS-422 ingasekela ama-node angu-10, kuyilapho i-RS-485 isekela ama-node angu-32, ngakho-ke ama-node amaningi akha inethiwekhi. I-topology yenethiwekhi ngokuvamile yamukela isakhiwo sebhasi esifaniswa netheminali futhi ayisekeli amanethiwekhi eringi noma enkanyezi. Lapho wakha inethiwekhi, amaphuzu alandelayo kufanele aqashelwe:
1. Sebenzisa ikhebula elisontekile njengebhasi bese uxhuma i-node ngayinye ochungechungeni. Ubude bomugqa ophumayo ukusuka ebhasini ukuya endaweni ngayinye kufanele bube bufushane ngangokunokwenzeka ukuze kuncishiswe umthelela wesiginali ebonisiwe kulayini ophumayo kusiginali yebhasi.
2. Kuzogxilwa ekuqhubekeleni phambili kwesici sebhasi, futhi ukubonakaliswa kwesignali kuzokwenzeka Ekuhlukanisweni kokunqanyulwa kwe-impedance. Lezi zimo ezilandelayo zingaholela kalula kulokhu kumiswa: izingxenye ezihlukene zebhasi zisebenzisa izintambo ezihlukahlukene, noma maningi kakhulu ama-transceiver afakwe eduze ndawonye engxenyeni ethile yebhasi, noma imigqa yegatsha emide kakhulu iholelwa ebhasini.
Ngamafuphi, isiteshi esisodwa esiqhubekayo sesignali kufanele sinikezwe njengebhasi.
Ungacubungula kanjani ubude bekhebula lokudlulisela uma usebenzisa isixhumi esibonakalayo se-RS485?
Impendulo: Uma usebenzisa isixhumi esibonakalayo se-RS485, ubude bekhebula obukhulu obuvunyelwe ukudluliswa kwesignali yedatha ukusuka kujeneretha ukuya kumthwalo emugqeni othize wokudlulisela kuwumsebenzi wezinga lesignali yedatha, elikhawulwa ngokuyinhloko ukuhlanekezelwa kwesignali nomsindo. Ijika lobudlelwane phakathi kobude obukhulu bekhebula nezinga lesignali eliboniswe esithombeni esilandelayo litholwa kusetshenziswa ikhebula yocingo ephothiwe eyinhloko engu-24AWG (enobubanzi bocingo obungu-0.51mm), enamandla olayini wokudlula ongu-52.5PF/M, kanye nokumelana nomthwalo wokugcina okungu-100 ohms.
Uma izinga lesignali yedatha lehla libe ngaphansi kuka-90Kbit/S, kucatshangwa ukuthi umkhawulo ovunyelwe wokulahlekelwa kwesignali we-6dBV, ubude bekhebula bukhawulelwe ku-1200M. Eqinisweni, ijika emfanekisweni lilondoloza kakhulu, futhi ekusebenziseni okungokoqobo, kungenzeka ukufeza ubude bekhebula obukhulu kunalo.
Uma usebenzisa izintambo ezinobubanzi obuhlukene bocingo. Ubude bekhebula obukhulu obutholakele buhlukile. Isibonelo, uma izinga lesignali yedatha lingu-600Kbit/S futhi kusetshenziswa ikhebula engu-24AWG, kungabonwa ngesibalo sokuthi ubude bekhebula obukhulu bungama-200m. Uma kusetshenziswa ikhebuli engu-19AWG (enobubanzi bocingo obungu-0.91mm), ubude bekhebula bungaba bukhulu kuno-200m; Uma kusetshenziswa ikhebula elingu-28AWG (elinobubanzi bocingo obungu-0.32mm), ubude bekhebula bungaba ngaphansi kuka-200m kuphela.
Ungafinyelela kanjani ukuxhumana kwamaphuzu amaningi kwe-RS-485?
Impendulo: I-transmitter eyodwa kuphela engathumela ebhasini le-RS-485 nganoma yisiphi isikhathi. Imodi ephindwe kabili, enenceku eyodwa kuphela. Imodi ye-duplex egcwele, isiteshi esikhulu singahlala sithumela, futhi isiteshi sezigqila singaba nokuthumela okukodwa kuphela. (Ilawulwa ngu-DE)
Kungaphansi kwaziphi izimo lapho ukufaniswa kwetheminali kufanele kusetshenziselwe ukuxhumana kwe-RS-485? Indlela yokunquma inani lokumelana? Ungawamisa kanjani ama-resistors amatheminali?
Impendulo: Ekudluliselweni kwesignali yebanga elide, ngokuvamile kuyadingeka ukuxhuma isixhasi esifanayo setheminali ekugcineni kokwamukela ukuze ugweme ukubonisa isignali kanye ne-echo. Inani lokumelana elihambisana netheminali lincike ezicini ze-impedance zekhebula futhi lizimele ngobude bekhebula.
I-RS-485 ngokuvamile isebenzisa ukupheya okusontekile (okuvikelekile noma okungavinjiwe), okunokumelana nokuphela ngokuvamile phakathi kuka-100 no-140 Ω, ngevelu evamile engu-120 Ω. Ekucushweni kwangempela, i-terminal resistor eyodwa ixhunywe ku-terminal nodes ezimbili zekhebula, eseduze kakhulu futhi ekude kakhulu, kuyilapho i-node ephakathi ayikwazi ukuxhunyaniswa nesinqamuleli setheminali, ngaphandle kwalokho amaphutha okuxhumana azokwenzeka.
Kungani isixhumi esibonakalayo se-RS-485 sisenokukhishwa kwedatha kumamukeli lapho ukuxhumana kumisiwe?
Impendulo: Njengoba i-RS-485 idinga ukuthi konke ukudlulisa kuvumela amasiginali okulawula ukuthi acishwe futhi ukwamukela kuvumela ukuthi kuvumeleke ngemva kokuthumela idatha, umshayeli webhasi ungena esimweni sokumelana okuphezulu futhi umamukeli angakwazi ukuqapha ukuthi kukhona yini idatha yokuxhumana entsha ebhasini.
Ngalesi sikhathi, ibhasi lisesimweni sokushayela (uma ibhasi linokumelana okufanayo okufanayo, izinga elihlukile lelayini A no-B ngu-0, okukhiphayo kowamukelayo akuqinisekile, futhi liyazwela ekushintsheni kwesignali ehlukile umugqa AB; uma kungekho ukuphela okufanayo okufanayo, ibhasi isesimweni sokungasebenzi kahle, futhi okuphumayo komamukeli akuqinisekile), ngakho-ke isengozini yokuphazamiseka komsindo wangaphandle. Lapho i-voltage yomsindo idlula umkhawulo wesiginali yokufaka (inani elijwayelekile ± 200mV), umamukeli uzokhipha idatha, okubangela ukuthi i-UART ehambisanayo ithole idatha engavumelekile, okubangela amaphutha okuxhumana ajwayelekile alandelayo; Esinye isimo singase senzeke ngesikhathi lapho isilawuli sokuvumela ukudluliswa sivuliwe/sivaliwe, okubangela ukuthi umamukeli akhiphe isignali, okungase futhi kubangele ukuthi i-UART yamukele ngokungalungile. Isixazululo:
1) Ebhasini lokuxhumana, indlela yokudonsela phezulu (umugqa A) ekugcineni kokufakwayo kwesigaba esifanayo nokudonsela phansi (umugqa B) ekugcineni kwesigaba esiphambene isetshenziselwa ukubophela ibhasi, ukuqinisekisa ukuthi okokukhiphayo kusendaweni izinga elimisiwe elithi "1"; 2) Faka esikhundleni sesifunda esibonakalayo ngemikhiqizo yochungechunge lwe-MAX308x enemodi yokuvimbela amaphutha eyakhelwe ngaphakathi; 3) Ukuqeda ngokusebenzisa izindlela zesofthiwe, okungukuthi, ukwengeza amabhayithi okuvumelanisa okuqala angu-2-5 ngaphakathi kwephakethe ledatha yokuxhumana, kuphela ngemva kokuba inhlokweni yokuvumelanisa ihlangatshezwana nayo lapho ukuxhumana kwedatha yangempela kungaqala.
Ukuncishiswa kwesignali kwe-RS-485 kuzintambo zokuxhumana
Isici sesibili esithinta ukudluliswa kwesignali ukuncishiswa kwesignali ngesikhathi sokudlulisa ikhebula. Ikhebula lokudlulisela lingabonwa njengesekhethi elinganayo eyakhiwe inhlanganisela yamandla asabalalisiwe, i-inductance esabalalisiwe, nokumelana.
Umthamo C osabalalisiwe wekhebula ukhiqizwa ikakhulukazi izintambo ezimbili ezihambisanayo zepheya elisontiwe. Ukuphikiswa kocingo kunomphumela omncane esignali lapha futhi kunganakwa.
Umthelela Wamandla Asabalalisiwe Ekusebenzeni Kokudluliselwa Kwebhasi Le-RS-485
Umthamo osabalalisiwe wekhebula ukhiqizwa ikakhulukazi izintambo ezimbili ezihambisanayo zamapheya asontekile. Ngaphezu kwalokho, kukhona i-capacitance esabalalisiwe phakathi kocingo nomhlabathi, okuyinto, nakuba incane kakhulu, ayikwazi ukunakwa ekuhlaziyeni. Umthelela wamandla asabalalisiwe ekusebenzeni kokudluliselwa kwebhasi ubangelwa ikakhulukazi ukudluliswa kwezimpawu ezibalulekile ebhasini, ezingavezwa kuphela ngezindlela "1" kanye "no-0". Ku-byte ekhethekile, njenge-0x01, isignali "0" ivumela isikhathi esanele sokushaja se-capacitor esabalalisiwe. Kodwa-ke, lapho isignali ethi "1" ifika, ngenxa yokushaja ku-capacitor esabalalisiwe, asikho isikhathi sokukhipha, futhi (Vin +) - (Vin -) - isenkulu kune-200mV. Lokhu kubangela ukuthi umamukeli akholelwe ngephutha ukuthi ngu-"0", ekugcineni kuholele kumaphutha okuqinisekiswa kwe-CRC kanye nalo lonke iphutha lokudlulisa uhlaka lwedatha.
Ngenxa yethonya lokusabalalisa ebhasini, amaphutha okudlulisa idatha ayenzeka, okuholela ekwehleni kokusebenza kwenethiwekhi iyonke. Kunezindlela ezimbili zokuxazulula le nkinga:
(1) Yehlisa i-Baud yokudluliswa kwedatha;
(2) Sebenzisa izintambo ezinama-capacitor amancane asabalalisiwe ukuze uthuthukise ikhwalithi yezintambo zokudlulisela.
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Isikhathi sokuthumela: Jul-06-2023