Iyini inqubo ye-RS485/ModBus-RTU?

I-interface yokuxhumana ye-RS485 iyindinganiso esetshenziswa kabanzi emkhakheni we-izimbonikanye ne-elekthronikhi yezentengiselwano yokuxhumana ngokulandelana. Yakhelwe ukubhekana nemikhawulo yezindinganiso zokuxhumana ngokulandelana zangaphambilini futhi ivumele ukudluliswa kwedatha okuthembekile emabangeni amade nasezindaweni eziyinselele kakhulu.

• Izimpawu Zikagesi
  • I-RS485 isebenzisa isignali yokuhlukanisa. Esikhundleni sentambo eyodwa yokudlulisa idatha njengakwezinye izixhumi ezilandelanayo (njenge-RS232), inezintambo ezimbili, ezivame ukubizwa ngokuthi u-A no-B. Umehluko we-voltage phakathi kwalezi zintambo ezimbili umele idatha. Umehluko we-voltage omuhle phakathi kwentambo u-A nentambo u-B (isb., A – B > 0.2 V) uchazwa njenge-logic 1, kuyilapho umehluko we-voltage ongemuhle (A – B < – 0.2 V) umele i-logic 0. Le ndlela yesignali yokuhlukanisa inikeza ukuzivikela okuhle kakhulu komsindo. Ezindaweni zezimboni ezinomsindo, lapho ukuphazamiseka kukagesi kuvame khona, umehluko we-voltage phakathi kwezintambo ezimbili cishe awuthinteki umsindo wangaphandle uma kuqhathaniswa nohlelo lwesignali oluphela kanye.
• Amandla Okuwa Okuningi
  • Esinye sezici ezibaluleke kakhulu ze-RS485 ukusebenza kwayo okune-multi-drop. Ibhasi elilodwa le-RS485 lingasekela ama-node (amadivayisi afinyelela ku-32). Amanye ama-transceiver e-RS485 athuthukile angaphatha ngisho nama-node amaningi, afinyelela ku-256 kwezinye izimo. Lokhu kuvumela amadivayisi amaningi, njengezinzwa, ama-actuator, kanye nabalawuli, ukuthi axhunywe ebhasini elifanayo lokuxhumana. Isibonelo, ohlelweni lokuzenzakalela kwesakhiwo, izinzwa eziningi zokushisa, izinzwa zomswakama, kanye nabalawuli bokukhanyisa bonke bangaxhunywa ebhasini elilodwa le-RS485, okunciphisa ubunzima bokuxhunywa kwezintambo kanye nokwakhiwa kwesistimu.
• Ibanga Lokudlulisa
  • I-RS485ingafinyelela amabanga okudlulisa amade kakhulu. Ezimweni ezinhle, ngesilinganiso sedatha esifinyelela ku-9600 bps, ingadlulisela idatha emabanga afinyelela ku-1200 amamitha. Njengoba izinga ledatha landa, ibanga lokudlulisa eliphezulu liyancipha. Isibonelo, ngesilinganiso sedatha esingu-1 Mbps, ibanga eliphezulu livame ukuba amamitha ayi-100. Leli khono lebanga elide lenza lifaneleke ezinhlelweni zokusebenza lapho amadivayisi esakazeke khona endaweni enkulu, njengasezimbonini zezimboni, kumagridi ahlakaniphile, kanye nezinhlelo zokuphepha.

• Ukusebenza kwe-Half – Duplex
  • I-RS485 ngokuyinhloko iyisixhumi sokuxhumana esiyingxenye yesigamu. Lokhu kusho ukuthi idatha ingadluliselwa kunoma iyiphi indlela, kodwa hhayi ngesikhathi esisodwa. Idivayisi eyodwa kuphela ebhasini engadlulisela idatha ngesikhathi, kuyilapho amanye amadivayisi ekwimodi yokwamukela. Ukuze uphathe lokhu, kudingeka indlela yokulawula ukuthi iyiphi idivayisi enelungelo lokudlulisa. Lokhu kuvame ukufezwa ngephrothokholi lapho amadivayisi enikezwa khona amakheli. Isibonelo, kuphrothokholi ye-Modbus RTU (Remote Terminal Unit), evame ukusetshenziswa ne-RS485, idivayisi eyinhloko ihlola amadivayisi esigqila ngokuthumela izicelo ngekheli elithile lesigqila esiqondiwe. Isigqila esiqondisiwe bese siphendula, futhi phakathi nalesi sikhathi, amanye amadivayisi ahlala kwimodi yokwamukela.
• Ukuhambisana kwephrothokholi
  • I-RS485Akuyona inqubo ngokwayo kodwa inikeza ungqimba olungokoqobo lwezinqubo ezahlukene zokuxhumana. Ngaphandle kwe-Modbus RTU, ezinye izinqubo ezifana ne-Profibus – DP (Process Field Bus – Decentralized Periphery) nazo zisebenzisa i-RS485 njengesixhumi esibonakalayo. Lezi zinqubo zichaza ukuthi idatha ifakwa kanjani kufreyimu, iqondiswa, kanye nephutha. Isibonelo, i-Modbus RTU isebenzisa ifomethi yohlaka oluhleliwe olunezingcezu zokuqala nezimisa, futhi ifaka ikhodi yokuhlola i-cyclic redundancy (CRC) ekugcineni kohlaka ngalunye ukuthola amaphutha okudlulisa. Lokhu kuhambisana nezinqubo eziningi kwenza i-RS485 ibe nokuguquguquka okukhulu futhi isebenze ezinhlelweni ezahlukene zezimboni nezentengiselwano.

• Ukuzenzekela Kwezimboni
  • Ezindaweni zezimboni, i-RS485 isetshenziselwa ukuxhumanisa abalawuli be-logic abahlelekayo (ama-PLC), izixhumanisi zomuntu nomshini (ama-HMI), izinzwa, kanye nama-actuator. Isibonelo, esitshalweni sokukhiqiza, ama-PLC angaxhumana nezinzwa eziningi (njengezinzwa zokusondelana, izinzwa zokucindezela) kanye nama-actuator (njengezinjini, ama-valve) ngenethiwekhi ye-RS485. Lokhu kwenza kube lula ukulawula kanye nokuqapha inqubo yokukhiqiza, ukuqinisekisa ukusebenza kahle kanye nokuphendula okusheshayo kunoma yiziphi izinguquko noma amaphutha.
• Izinhlelo Zokuphatha Izakhiwo
  • I-RS485 idlala indima ebalulekile ezinhlelweni zokuphatha izakhiwo. Isetshenziselwa ukuxhuma amadivayisi ahlukene okuzenzakalelayo kwezakhiwo, njengezinhlelo zokushisa, zokungenisa umoya, kanye nezokupholisa umoya (i-HVAC), izinhlelo zokulawula ukukhanya, kanye nezinhlelo zokuphepha. Isibonelo, isilawuli sokuphatha isakhiwo esiphakathi singaxhumana namayunithi amaningi e-HVAC nge-RS485 ukulungisa izinga lokushisa, umswakama, kanye nezilungiselelo zokugeleza komoya ngokuya ngokuhlala kwesakhiwo kanye nezimo zemvelo.
• Ukuphathwa kweGridi ehlakaniphile kanye namandla
  • Ngomongo wamagridi ahlakaniphile, i-RS485 isetshenziselwa ukuxhuma amamitha ahlakaniphile, amadivayisi okuqapha amandla, kanye nemishini yokusabalalisa amandla. Amamitha ahlakaniphile angadlulisela idatha yokusetshenziswa kukagesi endaweni yokuqoqwa kwedatha ephakathi nge-RS485. Le datha isetshenziselwa ukukhokhisa, ukuphatha umthwalo, kanye nokwenza ngcono igridi. Ngaphezu kwalokho, i-RS485 ingasetshenziswa ukulawula nokuqapha amadivayisi okulungisa amandla kanye neminye imishini kunethiwekhi yokusabalalisa amandla.