Kodi lingaliro la mawonekedwe a RS485 ndi chiyani poyamba?
Mwachidule, ndi muyezo wamakhalidwe amagetsi, omwe amatanthauzidwa ndi Telecommunications Viwanda Association ndi Electronic Industries Alliance. Maukonde olumikizirana a digito pogwiritsa ntchito mulingo uwu amatha kutumiza ma siginecha mogwira mtima pamtunda wautali komanso m'malo okhala ndi phokoso lalikulu lamagetsi. RS-485 imapangitsa kuti zitheke kukhazikitsa maukonde otsika mtengo komanso maulalo olumikizirana anthambi ambiri.
RS485 ili ndi mitundu iwiri ya mawaya: mawaya awiri ndi mawaya anayi. Dongosolo la waya anayi limatha kukwaniritsa kulumikizana kwa mfundo ndipo siligwiritsidwa ntchito kawirikawiri. Pakalipano, njira ziwiri zamawaya zamawaya zimagwiritsidwa ntchito kwambiri.
Mu uinjiniya wofooka wapano, kulumikizana kwa RS485 nthawi zambiri kumatengera njira yolumikizirana ndi akapolo, ndiye kuti, munthu m'modzi wokhala ndi akapolo angapo.
Ngati mumamvetsetsa mozama za RS485, mupeza kuti palidi chidziwitso chochuluka mkati. Choncho, tidzasankha nkhani zina zomwe nthawi zambiri timaziganizira mu magetsi ofooka kuti aliyense aphunzire ndi kumvetsa.
RS-485 Malamulo Amagetsi
Chifukwa cha chitukuko cha RS-485 kuchokera ku RS-422, malamulo ambiri amagetsi a RS-485 ndi ofanana ndi RS-422. Ngati kutengera koyenera kutengera, zopinga zoyimitsa ziyenera kulumikizidwa ndi chingwe chopatsira. RS-485 imatha kutengera mawaya awiri ndi njira zinayi zamawaya, ndipo mawaya awiriwa amatha kulumikizana ndi njira zambiri zolumikizirana, monga tawonera pa Chithunzi 6.
Mukamagwiritsa ntchito mawaya anayi, monga RS-422, amatha kulumikizana ndi mfundo, ndiye kuti, pangakhale chipangizo chimodzi chokha ndipo zina zonse ndi zida za akapolo. Komabe, ili ndi zowongolera poyerekeza ndi RS-422, ndipo imatha kulumikiza zida zina 32 pabasi mosasamala kanthu za njira yolumikizira mawaya anayi kapena awiri.
The RS-485 common mode voltage output ili pakati -7V ndi +12V, ndipo osachepera athandizira impedance ya RS-485 wolandila ndi 12k;, Dalaivala RS-485 angagwiritsidwe ntchito mu RS-422 maukonde. RS-485, ngati RS-422, ali pazipita kufala mtunda pafupifupi 1219 mamita ndi pazipita kufala mlingo wa 10Mb/s. Kutalika kwa peyala yopotoka moyenerera ndi yosiyana molingana ndi kuchuluka kwa kufalikira, ndipo kutalika kwa chingwe chomwe chatchulidwa chitha kugwiritsidwa ntchito ngati liwiro liri pansi pa 100kb / s. Kuthamanga kwapamwamba kwambiri kungathe kupezedwa pamtunda waufupi kwambiri. Nthawi zambiri, kuchuluka kwa kufalikira kwa ma 100 mita opotoka kutalika ndi 1Mb/s okha. RS-485 imafuna ma resistor awiri omwe ali ndi mtengo wokana wofanana ndi kulepheretsa kwa chingwe chotumizira. Mukatumiza pamtunda wamakona anayi, palibe chifukwa choletsa choletsa, chomwe nthawi zambiri sichifunikira pansi pa 300 metres. Choletsa choyimitsa chimalumikizidwa kumapeto onse a basi yotumizira.
Mfundo zazikuluzikulu za kukhazikitsa maukonde a RS-422 ndi RS-485
RS-422 imatha kuthandizira ma node 10, pomwe RS-485 imathandizira ma node 32, kotero ma node angapo amapanga maukonde. Netiweki topology nthawi zambiri imagwiritsa ntchito mabasi ofananirako ndipo sigwirizana ndi ma ring kapena nyenyezi. Popanga netiweki, mfundo zotsatirazi ziyenera kukumbukiridwa:
1. Gwiritsani ntchito chingwe chopotoka ngati basi ndikulumikiza node iliyonse motsatizana. Utali wa mzere wotuluka kuchokera ku basi kupita ku node iliyonse uyenera kukhala waufupi momwe ungathere kuti uchepetse kukhudzidwa kwa siginecha yowonekera pamzere wotuluka pa siginecha ya basi.
2. Chidziwitso chidzaperekedwa ku kupitiriza kwa chikhalidwe cha basi, ndipo kuwonetsera kwa chizindikiro kudzachitika pa Gulu la discontinuities of impedance. Zinthu zotsatirazi zitha kupangitsa kuti izi zitheke: magawo osiyanasiyana amabasi amagwiritsa ntchito zingwe zosiyanasiyana, kapena pali ma transceivers ambiri omwe amaikidwa palimodzi pagawo lina la basi, kapena mizere yanthambi yayitali kwambiri imatsogozedwa kupita kubasi.
Mwachidule, njira imodzi, yosalekeza yowonetsera iyenera kuperekedwa ngati basi.
Momwe mungaganizire kutalika kwa chingwe chotumizira mukamagwiritsa ntchito mawonekedwe a RS485?
Yankho: Pogwiritsira ntchito mawonekedwe a RS485, kutalika kwa chingwe chotalika chololedwa kufalitsa chizindikiro cha deta kuchokera ku jenereta kupita ku katundu pamtundu wina wotumizira ndi ntchito ya chiwerengero cha chizindikiro cha deta, chomwe chimakhala chochepa kwambiri ndi kusokonezeka kwa chizindikiro ndi phokoso. Mpiringidzo wa ubale pakati pa kutalika kwa chingwe ndi kuchuluka kwa ma siginecha akuwonetsedwa pachithunzi chotsatirachi amapezedwa pogwiritsa ntchito chingwe cha 24AWG chamkuwa chopotoka (chokhala ndi mainchesi a waya a 0.51mm), chokhala ndi mzere wodutsa mphamvu ya 52.5PF/M, ndi kukana kwamphamvu kwa 100 ohms.
Pamene chiwerengero cha chizindikiro cha deta chikutsika mpaka pansi pa 90Kbit / S, poganiza kuti chizindikiro chovomerezeka cha 6dBV chitayika, kutalika kwa chingwe kumangokhala 1200M. M'malo mwake, pamapindikira pachithunzichi ndizovuta kwambiri, ndipo pakugwiritsa ntchito moyenera, ndizotheka kukwaniritsa chingwe chokulirapo kuposa icho.
Mukamagwiritsa ntchito zingwe zokhala ndi ma diameter osiyanasiyana. Kutalika kwakukulu kwa chingwe chopezedwa ndi kosiyana. Mwachitsanzo, pamene chiwerengero cha chizindikiro cha deta ndi 600Kbit / S ndipo chingwe cha 24AWG chikugwiritsidwa ntchito, chikhoza kuwoneka kuchokera pa chithunzi kuti kutalika kwa chingwe ndi 200m. Ngati chingwe cha 19AWG (chokhala ndi waya awiri a 0.91mm) chikugwiritsidwa ntchito, kutalika kwa chingwe kungakhale kwakukulu kuposa 200m; Ngati chingwe cha 28AWG (chokhala ndi waya awiri a 0.32mm) chikugwiritsidwa ntchito, kutalika kwa chingwe kungakhale kochepa kuposa 200m.
Momwe mungakwaniritsire kulumikizana kwamitundu yambiri kwa RS-485?
Yankho: Ndi transmitter imodzi yokha yomwe ingatumize pa basi ya RS-485 nthawi iliyonse. Theka la duplex mode, ndi kapolo mmodzi yekha. Full duplex mode, master station imatha kutumiza nthawi zonse, ndipo malo ochitira akapolo amatha kutumiza kumodzi kokha. (Yoyendetsedwa ndi ndi DE)
Kodi kufananitsa ma terminal kumafunika kugwiritsidwa ntchito panjira ya RS-485 yolumikizana? Momwe mungadziwire mtengo wotsutsa? Momwe mungakhazikitsire ma terminal matching resistors?
Yankho: Pakutumiza kwa ma siginecha atali, ndikofunikira nthawi zambiri kulumikiza cholumikizira chofananira pamapeto olandila kuti tipewe kuwunikira komanso kumveka. The terminal yofananira kukana mtengo zimatengera mawonekedwe a impedance ya chingwe ndipo sizidalira kutalika kwa chingwe.
RS-485 nthawi zambiri imagwiritsa ntchito maulalo opotoka (otetezedwa kapena osatetezedwa), okhala ndi kukana kwapakati nthawi zambiri pakati pa 100 ndi 140 Ω, ndi mtengo wamba wa 120 Ω. Pakusintha kwenikweni, chopinga chimodzi cholumikizira chimalumikizidwa ndi ma terminal onse awiri a chingwe, chapafupi kwambiri komanso chakutali kwambiri, pomwe node yomwe ili pakatikati siyingagwirizane ndi chopinga cha terminal, apo ayi zolakwika zolumikizana zidzachitika.
Chifukwa chiyani mawonekedwe a RS-485 akadali ndi zotulutsa kuchokera kwa wolandila pomwe kulumikizana kwayimitsidwa?
Yankho: Popeza RS-485 imafuna kuti ma transmission onse azitha kuzimitsa zizindikiro zowongolera kuti zizimitsidwa ndipo kulandirira kumapangitsa kuti zikhale zomveka pambuyo potumiza deta, woyendetsa basi amalowa m'malo otsutsa kwambiri ndipo wolandira akhoza kuyang'anitsitsa ngati pali deta yatsopano yolankhulirana pa basi.
Panthawiyi, basi ili mumkhalidwe woyendetsa (ngati basi ili ndi kukana kofananira, kusiyana kwa mizere A ndi B ndi 0, kutulutsa kwa wolandirayo sikudziwika, ndipo kumakhudzidwa ndi kusintha kwa chizindikiro chosiyana. mzere AB; ngati palibe zofananira zofananira, basi ili m'malo otsekeka kwambiri, ndipo zotuluka za wolandila sizikudziwika), kotero zimakhala pachiwopsezo cha kusokonezedwa kwa phokoso lakunja. Phokoso la phokoso likadutsa polowera chizindikiro (mtengo wamba ± 200mV), wolandila amatulutsa deta, zomwe zimapangitsa kuti UART yofananira ilandire deta yosavomerezeka, zomwe zimapangitsa kuti pakhale zolakwika zolumikizana; Chinthu china chitha kuchitika panthawi yomwe kuwongolera kumathandizira kuyatsa / kuzimitsa, zomwe zimapangitsa kuti wolandila atulutse chizindikiro, zomwe zingayambitsenso UART kulandira molakwika. Yankho:
1) Pa basi yolumikizirana, njira yokokera mmwamba (Mzere A) kumapeto kwa gawo lomwelo ndikugwetsa pansi (B mzere) kumapeto kwa gawo lolowera kumagwiritsidwa ntchito kukakamiza basi, kuwonetsetsa kuti wolandila ali pa okhazikika "1" mlingo; 2) Bwezerani mawonekedwe ozungulira mawonekedwe ndi MAX308x mndandanda wazinthu zopangira zopangira zodzitetezera; 3) Kuchotsa kudzera mu mapulogalamu a mapulogalamu, ndiko kuti, kuwonjezera ma byte 2-5 oyambirira ogwirizanitsa mkati mwa paketi ya data yolankhulana, pokhapokha mutu wa kulunzanitsa utatha kuyankhulana kwenikweni kwa deta kungayambe.
Chizindikiro cha RS-485 mu zingwe zoyankhulirana
Chinthu chachiwiri chomwe chimakhudza kufalitsa chizindikiro ndi kuchepetsedwa kwa chizindikiro panthawi yotumiza chingwe. Chingwe chotumizira chikhoza kuwonedwa ngati dera lofanana lomwe limapangidwa ndi kuphatikiza kwa mphamvu yogawa, inductance yogawa, ndi kukana.
Mphamvu yogawidwa ya C ya chingwe imapangidwa makamaka ndi mawaya awiri ofanana a peyala yopotoka. Kukaniza kwa waya kumakhala ndi zotsatira zochepa pa chizindikiro apa ndipo kunganyalanyazidwe.
Mphamvu ya Kugawidwa Kwamagawo pa Mayendedwe Otumizira a RS-485 Bus
Mphamvu yogawidwa ya chingwe imapangidwa makamaka ndi mawaya awiri ofanana a awiri opotoka. Kuonjezera apo, palinso mphamvu yogawidwa pakati pa waya ndi nthaka, yomwe, ngakhale yaying'ono kwambiri, sichinganyalanyazidwe pakuwunika. Zotsatira za kugawidwa kwapang'onopang'ono pa kayendetsedwe ka kayendetsedwe ka mabasi makamaka chifukwa cha kutumiza zizindikiro zofunika pa basi, zomwe zingathe kuwonetsedwa mu "1" ndi "0" njira. Mwapadera, monga 0x01, chizindikiro "0" chimalola nthawi yokwanira yolipiritsa kwa capacitor yogawidwa. Komabe, chizindikiro cha "1" chikafika, chifukwa cha malipiro mu capacitor yogawidwa, palibe nthawi yoti mutulutse, ndipo (Vin +) - (Vin -) - akadali wamkulu kuposa 200mV. Izi zimapangitsa kuti wolandirayo akhulupirire molakwika kuti ndi "0", zomwe zimatsogolera ku zolakwika zotsimikizira za CRC ndi zolakwika zonse zotumizira deta.
Chifukwa cha chikoka cha kugawa pa basi, zolakwika zotumizira deta zimachitika, zomwe zimapangitsa kuchepa kwa ntchito yonse ya intaneti. Pali njira ziwiri zothetsera vutoli:
(1) Kuchepetsa Baud ya kutumiza deta;
(2) Gwiritsani ntchito zingwe zokhala ndi ma capacitor ang'onoang'ono omwe amagawidwa kuti apititse patsogolo mizere yotumizira.
Tsatirani CF FIBERLINK kuti mudziwe zambiri zaukadaulo wachitetezo !!!
Ndemanga: Kugawana zinthu zapamwamba ndi aliyense ndikofunikira. Nkhani zina zimachokera pa intaneti. Ngati pali zophwanya malamulo, chonde tidziwitseni ndipo tidzathana nazo posachedwa.
Nthawi yotumiza: Jul-06-2023