Ngobuchwepheshe be-SCM obuvuthiwe nobuthuthukisiwe ekuqaleni kweminyaka yama-80, imakethe yezinsimbi emhlabeni ilawulwa amamitha ahlakaniphile, okubangelwa izimfuno zolwazi lwebhizinisi.Esinye sezimo ezibalulekile ukuze amabhizinisi akhethe amamitha ukuba nokuxhumana kwenethiwekhi.Ukukhishwa kwesignali yedatha ye-analog yokuqala kuyinkqubo elula, khona-ke i-interface yensimbi i-interface ye-RS232, engafinyelela ukuxhumana kwephuzu kuya kwephuzu, kodwa ngale ndlela ayikwazi ukufeza umsebenzi wokuxhumana, khona-ke ukuvela kwe-RS485 kuxazulula le nkinga.
I-RS485 iyindinganiso echaza izici zikagesi zabashayeli nabamukeli ezinhlelweni zamaphoyinti amaningi edijithali.Izinga lichazwa yiTelecommunications Industry Association kanye ne-Electronics Industry Union.Amanethiwekhi okuxhumana edijithali asebenzisa leli zinga angadlulisela amasiginali ngempumelelo ebangeni elide nasendaweni yomsindo we-elekthronikhi ophezulu.I-RS-485 yenza kube nokwenzeka ukucushwa kokuxhuma amanethiwekhi endawo kanye nezixhumanisi eziningi zokuxhumana zamagatsha.
RS485inezinhlobo ezimbili zezintambo zesistimu yezintambo ezimbili kanye nesistimu yezintambo ezine.Isistimu yezintambo ezine ingafinyelela imodi yokuxhumana yephoyinti nephoyinti, engavamile ukusetshenziswa.Imodi yezintambo ezimbili zesistimu ivame ukusetshenziswa ngesakhiwo se-topology yebhasi futhi ingaxhunywa kumanodi angu-32 kakhulu ebhasini elifanayo.
Kunethiwekhi yokuxhumana ye-RS485, ukuxhumana kwe-main-sub ngokuvamile kusetshenziswa, okungukuthi, imitha eyinhloko ixhunywe nama-sub metres amaningi.Ezimweni eziningi, ukuxhumana kwesixhumanisi sokuxhumana se-RS-485 kumane kuxhunywe nepheya elisontekile lepheya elithi "A" kanye "B" ekugcineni kwesixhumi esibonakalayo ngasinye, kuyilapho kushaywa indiva ukuxhumana komhlabathi wesignali.Le ndlela yokuxhuma ezikhathini eziningi ingasebenza ngokujwayelekile, kodwa ingcwabe ingozi enkulu efihliwe.Esinye sezizathu ukuphazanyiswa kwemodi evamile: I-RS - 485 interface isebenzisa indlela yokudlulisa imodi ehlukile futhi ayidingi ukubona isignali kunoma iyiphi ireferensi, kodwa ibona umehluko we-voltage phakathi kwezintambo ezimbili, okungase kuholele ekungazini kwe-voltage yemodi evamile. ububanzi.I-RS485 transceiver common-mode voltage ranges between – 7V and + 12V futhi yonke inethiwekhi ingasebenza ngokujwayelekile, kuphela uma ihlangabezana nezimo ezingenhla,;Lapho i-voltage yemodi evamile yomugqa wenethiwekhi idlula lolu hlu, ukuzinza nokuthembeka kokuxhumana kuzothinteka, futhi ngisho nesixhumi esibonakalayo sizolimala.Isizathu sesibili inkinga ye-EMI: ingxenye yemodi evamile yesiginali yokuphuma komshayeli othumelayo idinga indlela yokubuya.Uma ingekho indlela ephansi yokubuyisela ukumelana (indawo yesignali), izobuyela emthonjeni ngesimo semisebe, futhi lonke ibhasi lizokhipha amaza kagesi ngaphandle njengothi olukhulukazi.
Izindinganiso ezijwayelekile zokuxhumana yi-RS232 kanye ne-RS485, echaza i-voltage, impedance, njll., kodwa ayichazi iphrothokholi yesofthiwe.Ihlukile ku-RS232, izici ze-RS485 zifaka:
1. Izici zikagesi ze-RS-485: i-logic “1″ imelwe umehluko we-voltage phakathi kwemigqa emibili njengo-+ (2 — 6) V;Okunengqondo okuthi “0″ imelelwa umehluko wevoltheji phakathi kwemigqa emibili njengokuthi – (2 — 6) V. Uma izinga lesignali yesixhumi esibonakalayo liphansi kune-RS-232-C, akulula ukulimaza i-chip yesekethe yesixhumi esibonakalayo, futhi izinga liyahambisana nezinga le-TTL, ngakho-ke kulula ukuxhuma nesekethe ye-TTL.
2. Izinga eliphezulu lokudluliswa kwedatha lika-RS-485 ngu-10Mbps.
3. Isixhumi esibonakalayo se-RS-485 sinamandla, okungukuthi, ukuphazamiseka okuhle kokulwa nomsindo.
4. Ibanga eliphezulu lokudlulisa le-RS-485 liyimitha engamamitha angu-4000 inani elijwayelekile, empeleni lingafinyelela kumamitha angu-3000 (idatha yethiyori, ekusebenzeni okungokoqobo, ibanga elilinganiselwe lifika kuphela kumamitha angu-1200), ngaphezu kwalokho, RS-232 -C interface ivumela kuphela ukuxhuma i-transceiver engu-1 ebhasini, okungukuthi, umthamo wesiteshi esisodwa.I-interface ye-RS-485 ebhasini ivunyelwe ukuxhuma kuma-transceivers angu-128.Okusho ukuthi, ngamandla eziteshi eziningi, abasebenzisi bangasebenzisa isixhumi esibonakalayo esisodwa se-RS-485 ukusetha kalula inethiwekhi yamadivayisi.
Ngenxa yokuthi isixhumi esibonakalayo se-RS-485 sinokuphazamisa okuhle kokulwa nomsindo, izinzuzo ezingenhla zebanga elide lokudlulisela kanye nekhono leziteshi eziningi kuyenza ibe isixhumi esibonakalayo esithandwayo.Ngenxa yokuthi inethiwekhi eyi-half-duplex eyakhiwe isixhumi esibonakalayo se-RS485 ngokuvamile idinga izintambo ezimbili kuphela, isixhumi esibonakalayo se-RS485 sithatha ukudluliswa kwamapheya asontekile avikelekile.Isixhumi esibonakalayo se-RS485 sisebenzisa i-9-core plug block ye-DB-9, futhi isixhumi esibonakalayo setheminali ehlakaniphile i-RS485 sisebenzisa i-DB-9 (imbobo), futhi isixhumi esibonakalayo sekhibhodi i-RS485 esixhunywe nekhibhodi sisebenzisa i-DB-9 (inaliti).
Isikhathi sokuthumela: Mar-15-2021