Ngetekhnoloji yeSCM esele ikhulile kwaye iphuhlisiwe ekuqaleni kweminyaka yama-80, urhwebo lwezixhobo zehlabathi lulawulwa ziimitha ezikrelekrele, ezibalelwa kwiimfuno zolwazi lweshishini.Enye yeemeko eziyimfuneko kumashishini ukukhetha iimitha kukuba nojongano lonxibelelwano lwenethiwekhi.Isiphumo sokuqala somqondiso we-analog yedatha yinkqubo elula, ngoko i-interface yesixhobo yi-RS232 interface, enokufikelela kwi-point-to-point yonxibelelwano, kodwa le ndlela ayikwazi ukufezekisa umsebenzi wenethiwekhi, ngoko ukuvela kwe-RS485 kusombulula le ngxaki.
I-RS485 ngumgangatho ochaza iimpawu zombane zabaqhubi kunye nabamkeli kwiinkqubo ezilinganayo ze-digital multipoint.Umgangatho uchazwa yi-Telecommunications Industry Association kunye ne-Electronics Industry Union.Uthungelwano lwedijithali lonxibelelwano olusebenzisa lo mgangatho lunokuhambisa imiqondiso ngokufanelekileyo kumgama omde kunye nokusingqongileyo kwengxolo ephezulu ye-elektroniki.I-RS-485 yenza kube nokwenzeka ulungelelwaniso lothungelwano lothungelwano lwasekuhlaleni kunye namakhonkco onxibelelwano amasebe amaninzi.
RS485ineentlobo ezimbini zocingo lwenkqubo yocingo ezimbini kunye nenkqubo yocingo ezine.Inkqubo yocingo emine inokufezekisa kuphela imo yonxibelelwano ye-point-to-point, engafane isetyenziswe.Imowudi yocingo yocingo ezimbini isetyenziswa ngokuqhelekileyo kunye nesakhiwo se-topology yebhasi kwaye inokudityaniswa kwiinodi ezingama-32 kakhulu kwibhasi enye.
Kuthungelwano lonxibelelwano lwe-RS485, unxibelelwano olungundoqo lusetyenziswa ngokubanzi, oko kukuthi, imitha engundoqo idityaniswe ne-submitha ezininzi.Kwiimeko ezininzi, uxhulumaniso lwe-RS-485 ikhonkco lonxibelelwano ludibaniswa nje kunye neebini eziphothiweyo ze "A" kunye ne "B" ekupheleni kwe-interface nganye, ngelixa ungayihoyi uxhulumaniso lomhlaba wesignali.Le ndlela yokudibanisa kwiimeko ezininzi inokusebenza ngokuqhelekileyo, kodwa ingcwabe ingozi enkulu efihliweyo.Esinye sezizathu luphazamiseko lwemowudi eqhelekileyo: I-RS - 485 ujongano lwamkela indlela yokuhanjiswa kwemowudi eyahlukileyo kwaye akufuneki ukuba ibone umqondiso ngokuchasene nayo nayiphi na ireferensi, kodwa qaphela umahluko wombane phakathi kweengcingo ezimbini, ezinokukhokelela ekungazini kombane wemowudi eqhelekileyo. uluhlu.I-RS485 i-transceiver ye-voltage ye-voltage eqhelekileyo iphakathi kwe-7V kunye + 12V kunye nenethiwekhi yonke inokusebenza ngokuqhelekileyo, kuphela xa ihlangabezana nezi meko zingentla,;Xa i-voltage yemowudi eqhelekileyo yomgca wenethiwekhi idlula olu luhlu, ukuzinza kunye nokuthembeka konxibelelwano kuya kuchaphazeleka, kwaye i-interface iya konakala.Isizathu sesibini yingxaki ye-EMI: inxalenye yendlela eqhelekileyo yomqondiso wemveliso yomqhubi othumelayo idinga indlela yokubuya.Ukuba akukho ndlela isezantsi yokubuya yokumelana (umhlaba wesiginali), iya kubuyela kumthombo ngendlela yemitha, kwaye yonke ibhasi iya kukhupha amaza ombane ngaphandle njenge-eriyali enkulu.
Imigangatho yonxibelelwano oluqhelekileyo yi-RS232 kunye ne-RS485, echaza amandla ombane, i-impedance, njl., kodwa ayichazi iprothokholi yesofthiwe.Ukwahluka kwi-RS232, amanqaku e-RS485 abandakanya:
1. Iimpawu zombane ze-RS-485: ingqiqo "1" imelwe ngumahluko wombane phakathi kwemigca emibini njenge + (2 — 6) V;Ingqiqo "0" imelwe ngumahluko we-voltage phakathi kwemigca emibini njengoko - (2 — 6) V. Xa inqanaba lesignali ye-interface lingaphantsi kwe-RS-232-C, akulula ukonakalisa i-chip ye-interface yesekethe, kunye nenqanaba lihambelana nenqanaba le-TTL, ngoko kulungele ukudibanisa kunye nesekethe ye-TTL.
2. Izinga eliphezulu lokudluliselwa kwedatha ye-RS-485 yi-10Mbps.
3. I-RS-485 i-interface yomelele, oko kukuthi, ukuphazamiseka okulungileyo kokuchasana nengxolo.
4. Umgama ophezulu wokuhanjiswa kwe-RS-485 i-interface ye-4000 yeenyawo zexabiso eliqhelekileyo, ngokwenene linokufikelela kwiimitha ezingama-3000 (idatha ye-theoretical, ekusebenzeni okusebenzayo, umda womda ufikelela kuphela kwi-1200 yeemitha), ngaphezu koko, i-RS-232 -C interface ivumela kuphela ukudibanisa i-transceiver ye-1 kwibhasi, oko kukuthi, umthamo wesikhululo esisodwa.I-RS-485 interface kwibhasi ivumelekile ukuba idibanise ukuya kwi-128 transceivers.Oko kukuthi, ngesakhono sezikhululo ezininzi, abasebenzisi banokusebenzisa ujongano olulodwa lwe-RS-485 ukuseta ngokulula inethiwekhi yezixhobo.
Ngenxa yokuba ujongano lwe-RS-485 lunokuphazamiseka okuhle kokuchasana nengxolo, iingenelo ezingentla zomgama wothumelo olude kunye nekhono lezikhululo ezininzi zenza ujongano olukhethiweyo lweserial.Ngenxa yokuba i-half-duplex network yenziwe nge-RS485 interface ifuna iingcingo ezimbini kuphela, ujongano lweRS485 luthatha uthungelwano olujijekileyo olukhuselekileyo.I-RS485 ye-interface ye-interface ye-RS485 isebenzisa i-9-core plug block ye-DB-9, kunye ne-terminal ehlakaniphile i-RS485 interface isebenzisa i-DB-9 (umngxuma), kunye ne-keyboard interface RS485 edityaniswe nebhodibhodi isebenzisa i-DB-9 (inaliti).
Ixesha lokuposa: Mar-15-2021