RS-485 uxhumano nokulawula

RS-485 kuyinto ejwayelekile ukuthi kwase kuqala yokutholwa Electronic Industries Association. Kuze kube manje, lo amadili Standard izici kagesi zonke izinhlobo abamukelayo kanye zidlulisele elisetshenziswa ezihlukahlukene izinhlelo olinganiselayo digital.

Kuyini lokhu?

Phakathi izazi RS-485 yigama sasivumela ethandwa kokusetshenziswa kubonwa, okuyinto kabanzi yezimboni eyahlukene inqubo control izinhlelo yokuxhuma abalawuli eziningana kanye ezihlukahlukene namanye amadivayisi phakathi kwazo. Umehluko omkhulu phakathi esibonakalayo we bebubuncani RS-232 ukuthi inikeza inyunyana ngesikhathi esifanayo of izinhlobo eziningana imishini.

Ukusebenzisa RS-485 kuhlinzekwe yinkampani exchange ngesivinini kolwazi phakathi kumadivayisi multiple ngokusebenzisa olulodwa-wire zokuxhumana isixhumanisi imodi isigamu-Duplex. It is kabanzi embonini yesimanje e inqubo PC.

Ububanzi nesivinini

Esebenzisa le ndinganiso kufinyelelwa ukusakaza ulwazi ngesivinini abafika kwabangu-10 Mbit / s, kuyilapho inani okunokwenzeka ebangeni ngqo incike ijubane lapho idatha adluliswa. Ngakho, ukuqinisekisa idatha ngesivinini esiphezulu angadluliselwa akuyona ezingaphezu kuka-120 m, kuyilapho ngesivinini 100 kbit / s lwazi ukusakaza ezingaphezu kuka 1200 amamitha.

Inombolo kudivayisi ngokuhlanganisa

Inani lamadivayisi ezingaba hlanganisa RS-485 esibonakalayo ngeke ngqo zincike transceivers yiphi idivayisi isetshenziswa. Lidlulisela ngayinye yakhelwe ukulawula kanyekanye 32 by abamukelayo ejwayelekile, kodwa kufanele kuqondwe ukuthi kukhona abamukelayo, impedance yokufaka 50%, 25% noma ingxenye encanyana standard, futhi uma ukusetshenziswa imishini enjalo Inani seliphelele lamadivayisi kuzokhulisa ngokufanele.

Nezixhumi kanye yezifiso

RS-485 ikhebula akuyona zilandele izilinganiso ezithile iyiphi ezithile ozimele format idatha noma olandelwayo. Ezimweni eziningi usizo idatha esetshenzisiwe ncamashi ozimele efanayo, esebenzisa RS-232, okusho ukuthi izingcezu idatha, kuqale futhi ayeke izingcezu, futhi silinganiso izingcezu, uma kunesidingo.

zokuxhumana yezifiso ukusebenza izinhlelo eziningi zalezi zinsuku kwenziwa 'ngenkosi-nceku ", okungukuthi, uhlobo oluthile idivayisi kunethiwekhi esihamba phambili, abese eqala isicelo exchange ngokuthumela isinyathelo phakathi wonke amadivayisi inceku kuhluke amakheli okunengqondo. Iziphakamiso eziyisisekelo ezidume kakhulu namuhla Modbus RTU.

Kuyaphawuleka ukuthi ikhebuli RS-485 has futhi abanye uhlobo oluthile nezixhumi noma soldered, okungukuthi, singenzeka ngocingo nezixhumi, le DB9 nabanye.

uxhumano

Ngokuvamile, usebenzisa le esibonakalayo ihlangabezana kunethiwekhi yasendaweni, elihlanganisa transceivers amaningi.

Kuphethe RS-485 uxhumano, udinga ngobuciko sihlanganise nomunye izifunda isignali, esivame ukubizwa ngokuthi A no B. Kulokhu, kubuyekezwe akuyona umbono wesabeka kangaka, amadivayisi nje uxhumeke ngeke zisebenze.

Amacebo eziwusizo

Ukusebenzisa RS-485 esibonakalayo, kufanele inake izici eziningana umsebenzi wakhe:

• Imvelo elilungile kakhulu isignali ukudluliswa - kuyinto ikhebula ye pair elisontiwe.
• Ikhebula ekugcineni ngempela kudingeka ukuze ungawuzwa ngosizo ezikhethekile esibulalayo resistors.
• Network, esebenzisa indinganiso noma USB RS-485, kufanele badedele ngaphandle amagatsha le yomphindwa ibhasi.
• Amadivayisi kumele exhunywe kwi-izintambo ikhebula njengoba short ngangokunokwenzeka.

Kulokhu, isixazululo esingcono kakhulu ukuze badedele RS-485 esibonakalayo, - a pair elisontiwe, njengoba kuyahluka kancane yisinanakazana isignali ngemisebe futhi has a ukuvikeleka okuhle kakhulu ukuphazamiseka. Uma imishini izosebenza ngaphansi eliphezulu kakhulu umsindo wangaphandle, kungcono sebenzisa intambo, wamvikela pair nesisontekile, kuhlangene phansi zokuzivikela abaphatha isihlangu ikhebula.

sivumelwano

Esebenzisa esibulalayo resistors ejwayelekile noma USB RS-485 inikeza ukubambisana okuphelele ukuphela evulekile komugqa ikhebula kulandele ukubuqeda ngokuphelele kungenzeka isignali reflection.

Standard ukumelana resistors kuyafaneleka isici impedance ikhebula nalabo izintambo okuncike ezisontekile-pair ikhebula, ezimweni eziningi, i kunenzuzo cishe 100-120 ohms. Ngokwesibonelo, sasivumela ethandwa namuhla UTP-5 ngokusebenzisa ikhebula, kabanzi lisetshenziswe-Ethernet laying nqubo has impedance sici ohms 100. Ukuze uthole ezinye izinketho ikhebula ingasetshenziswa kanye nanoma yimiphi eminye ihlelo.

Resistors, uma kunesidingo, kungaba uphawu ngesikhathi izikhonkwane ikhebula isixhumi kakade idivayisi yokugcina. Akuvamile resistors ezifakiwe kule divayisi, ukuze ukuxhumana Resistor kuyadingeka ukuze ufake jumper. Kulokhu, uma kwenziwa edivayisini ngokuphelele umugqa rassoglasovyvaetsya. Futhi ukuze kuqinisekiswe ukusebenza evamile lonke uhlelo, kudingeka ukuba uxhume cap ezifanayo.

amazinga isignali

RS-485 isebenzisa olinganiselayo idatha wesifunda yezokusakaza, okungukuthi, amazinga voltage phezu isignali imigqa A no B kuzohluka abaphikisayo.

Esebenzisa inzwa lokufanele liniketwe isiginali ezingeni 1.5 at ithwele umthwalo omningi, futhi akukho kuka 6 esimweni uma idivayisi idling. Izinga voltage kukalwa differentially isihlobo kwezinye umugqa isignali ngamunye.

Lapho umamukeli Ingubuncane wathola isignali ezingeni kunoma isiphi isimo kufanele ibe sezingeni hhayi ngaphansi kuka-200 mV.

ukufuduka

Esimeni lapho kungekho isignali ngesikhathi imigqa isignali, kancane offset kwenzeka, okuyinto uthola ukuvikeleka umamukeli ngokumelene positives bamanga.

Ochwepheshe batusa ukwenza offset lithé ukuba likhudlwana kune-200 mV, kusukela lesi silinganiso kuyinto isignali a okuhambisanayo zone kungathembeki okokufaka ejwayelekile. Kulokhu, A uchungechunge edonswa isigxobo omuhle umthombo, kuyilapho chain B edonswa ukuze ezivamile.

Ngokwesibonelo

Ngokuhambisana ukufuduka oyifunayo futhi amandla supply voltage ukubala wenziwa amahlelo resistors. Ngokwesibonelo, uma kubalulekile ukuthola offset at 250 mV usebenzisa resistors esibulalayo R _T = 120 ohms ukuthi umthombo has a voltage 12 V. Kusukela kulokhu resistors ezimbili axhunyiwe parallel komunye nomunye futhi ngokuphelele acabangele umthwalo ohlangothini umamukeli, lamanje noma ukuchema kuzo kuyinto 0,0042 a, kuyilapho ukumelana ingqikithi circuit ukuchema kwakukhinyabeza 2857 ohms. R _ukubona kulokhu kuyoba ngu-1400 ohms, ngakho udinga ukukhetha ezinye ihlelo eliseduze.

Isibonelo kungaba 1.5 kohm Resistor isetshenziswa, eyenzelwe displacement, kanye Resistor lwangaphandle ukuze 12 volts. Ngaphezu kwalokho, e yethu simiso sezinto isilawuli decoupled ugesi okukhipha, okuyinto eyilungu ushayela emaketangeni ingxenye.

Yiqiniso, zikhona nezinye embodiments eziningi nokuchema ezisebenzisa RS-485 Converter kanye nezinye izakhi kodwa noma kunjalo, le ekusebenziseni ilungiselelo noma ukuchema kuzo izifunda, kubalulekile ukuba acabangele yokuthi isayithi, ezizohlinzeka ke, uzobe ngezikhathi shaqa noma bagcina kungaba zisuswe ngokuphelele kunethiwekhi.

Uma kukhona offset ke circuit umthamo A lutho ngokuphelele kuyinto omuhle mayelana wesifunda B, okuyinto ubhekisela lapho idivayisi entsha ixhunywe izintambo ikhebula ngaphandle kophawu.

Izintambo zikagesi ezisobala engalungile futhi ukuhlanekezela

Buciko izincomo ngenhla ivumela ukudluliswa ejwayelekile yezinzwa e amaphuzu ezahlukene inethiwekhi, uma esetshenziswa njengoba isisekelo sokuthethelelwa RS-485 olandelwayo. Uma wagcwalisa ezinye izidingo okungenani Kuyovela ukuhlanekezela. Ukuhlanekezela ephawuleka kakhulu ziqala ukuvela kuleli cala, uma izinga idatha ingaphezu 1 Mbit / s, kepha eqinisweni, ngisho esimweni ngesivinini aphansi is hhayi Kunconywa ukuba indiva lezi zincomo, ngisho noma inethiwekhi "imisebenzi kahle."

Indlela uhlelo?

Phakathi izinhlelo, ezihlukahlukene izinhlelo zokusebenza ezisebenza namadivayisi usebenzisa RS-485 idabula noma amanye amadivayisi nale esibonakalayo, kudingeka ucabangele amanye amaphuzu abalulekile. Nampa:

• Ngaphambi uzoqala ukuthumela udaba, udinga ngempela kusebenze Lidlulisela. Naphezu kweqiniso lokuthi, ngokusho emithonjeni ezithile, ayiswe kungathatha indawo ngokushesha ngemuva kokuqinisekiswa, abanye ochwepheshe batusa misa isikhashana kokuqala, okuyinto ngesikhathi kuyoba ulingana ngesilinganiso kwepulanka linye. Kulokhu, yokwamukela efanele ngesikhathi uhlelo ukuhlonza ngokugcwele amaphutha lezivakashi nokufeza inqubo ukuzinza ukuze silungiselele okwalandela idatha reception.
• Ngemva ibhayithi lokugcina idatha ikhishwa, ibuye Kunconywa ukuba ume phambi nokunqamula idivayisi RS-485. Kahle kahle, lokhu kungenxa yokuthi amarejista le serial port isilawuli ngokuvamile kanyekanye samanje ezimbili, eyokuqala okuyinto parallel itheku futhi senzelwe ekutholeni idatha, kanti eyesibili shift okukhipha isetshenziswa kanye okukhiphayo serial. Noma yimuphi ukudluliswa isilawuli uphazamisa kwakheka uma irejista okokufaka nolokubhujiswa lapho ulwazi isivele enikeziwe kwirejista shift, kodwa ingakamiswa ikhishwe. Kungenxa yalesi sizathu ukuthi emva kokuba ukusakazwa uphazanyiswa, kubalulekile ukusekela kokuhlaba ikhefu isikhathi esithile ngaphambi nokunqamula Transmitter, okuyinto kumele sibe sesikhathini mkhulu kunezinhliziyo ibhithi mayelana 0.5 kuka uzimele. Ukuze afeze izibalo eqonde kakhulu Kunconywa ukuba sihlole ngokuningiliziwe lobuchwepheshe imibhalo esetshenziswa port serial isilawuli.
• Njengoba Transmitter, umamukeli, futhi mhlawumbe RS-485 Converter ixhunywe umugqa owodwa, ungumnikazi owamukelayo uyoqonda njengoba ukudluliselwa eyenziwa Lidlulisela lalo. Kaningi kuyenzeka ukuthi kumasistimu libhekene ukufinyelela okungahleliwe umugqa, lesi sici isetshenziswa inqubo kokuhlola ukushayisana phakathi omoya ezimbili. In izinhlelo ezivamile ezisebenza ngokuhambisana "master-nceku", e-inqubo yokudlulisa Kunconywa ukuvala ngokugcwele uphazamisa kusukela umamukeli.

Ukucushwa "ibhasi" format

Lokhu isikhombimsebenzisi unikeza kungenzeka ngokuhlanganisa amadivayisi usayizi "ibhasi" lapho wonke amadivayisi ndawonye usebenzisa i-pair olulodwa izintambo. Kulokhu, zokuxhumana line is compulsorily bavumelana EOL resistors both qeda.

Ukuqinisekisa ukuvumelana elisungulwe Kulokhu resistors libhekene ukumelana 620 ohms. Ngaso sonke isikhathi efakwe kudivayisi nesibongo exhunywe kwi-line. amadivaysi advantageously esimanjemanje kakhulu futhi samanje ngaphakathi ukumelana ofanayo, okungase ngokuzikhethela zifakwe umugqa ngokubeka Jumpers on insimbi ibhodi ekhethekile.

Njengoba isimo kwezidingo jumper ekuqaleni ifakiwe, kubalulekile ekuqaleni ukuba bawasuse wonke amadivaysi, ngokulandelana, ngaphandle nesibongo exhunywe kwi-line. I repeater converters imodeli S2000-PI ngamunye okukhipha ofanayo impedance esitshalweni ngumuntu inkinobho, kuyilapho amadivayisi S2000-COP libhekene C2000-K integrated kunqanyulwe isivumelwano se impedance, lapho ibhuloho, kudingeka uxhumano yayo ayitholakali.

Ukuze uqinisekise umugqa eside yokuxhumana, kutuswa ukusebenzisa ukuphinda ezikhethekile, transponder, owufanelekela nge-othomathikhi ngokugcwele eshintshashintshayo isiqondiso.

Ukucushwa kwe "inkanyezi" format

Noma yimuphi legatsha e emigqeni RS-485 akuzona ezifiselekayo, ngoba kulesi simo kukhona isignali ukuhlanekezela ngokwanele, kodwa iphuzu eliwusizo umbono, bakwazi ukuvimbela kwenzeka ukuthi kukhona obuphelele encane amagatsha. Kulokhu-ke akudingi ukufakwa resistors amagatsha ahlukene.

I RS-485 ohlelweni ukusatshalaliswa, esiyinyama esilawulwa kusukela panel, futhi uma idivayisi zokugcina exhunywe kwi-line efanayo, kodwa ezidla emithonjeni ehlukene, uzodinga sihlanganise neketanga 0 wonke amadivaysi kanye kude ukuze kuqinisekiswe umgwaqo nekhono yabo. Uma ngabe le mfuneko is hhayi bahlangana ke elawulwa kude ungaba uxhumano engazinzile kumadivayisi. Uma ikhebula izosetshenziselwa nge eziningana ezisontekile wire ngazimbili, kulesi simo ngoba engaba ukulingana wesifunda ingasetshenziswa pair nhlobo uma kunesidingo. Phakathi kwezinye izinto, futhi linikeza kungenzeka ngokusebenzisa pair kwakuvikela ezisontekile kwenzeka ukuthi akukho indiza phansi.

Yini okufanele mina cabanga?

Advantageously samanje kakhulu lapho sidlula equipotential wire, kuyinto encane ngokwanele, kodwa uma kwenzeka 0 V amadivaysi noma ngokwabo ugesi uxhumeke kwi-sikhwela ibhesi wendawo eziningana isisekelo umehluko ezingaba phakathi izifunda ezahlukene 0V kungenzeka amayunithi eziningana, futhi kwezinye izimo, ngisho amashumi volts, kuyilapho wamanje egeleza ngokusebenzisa ezingaba zokulinganiswa wesifunda kungaba ephawulekayo ngempela. Lokhu kuyimbangela ezivamile yokuthi kukhona uxhumano engazinzile phakathi akude nedivaysi, ngakho ukuthi bangase bahluleke ngisho.

Kungenxa yalesi sizathu ukuthi ufuna ukuvala amathuba phansi wesifunda 0 noma, okungenani, endaweni ngaleli ketanga ngesikhathi esithile ezithile. Kudingeka nokuba sicabange ukuthi singakwazi yini interconnection kuka-0 no uchungechunge emhlabeni zokuzivikela ekhona imishini esetshenziswa ohlelweni OPS.

Ngesikhathi amasayithi, libhekene ngempela ezisindayo imvelo kagesi, inikeza ikhono ukuxhuma ikhebula inethiwekhi ngokusebenzisa "kwakuvikela pair ezisontekile". Kulokhu, kungase kube khona umkhawulo ephansi ububanzi, kusukela capacitance ikhebula kuyinto ephakeme.