RS232 vs RS485
RS232 thiab RS485 yog cov qauv rau cov ntaub ntawv cables. Txhawm rau sib pauv cov ntaub ntawv ntawm cov nodes ntawm lub network, cov cuab yeej siv feem ntau yog cov tsav tsheb thiab cov txais. Nws yog ib qho nyuaj rau teeb tsa lub network nrog kev hloov cov ntaub ntawv du yog tias muaj suab nrov, qhov sib txawv hauv av, tsis sib haum ntawm impedance thiab lwm yam kev phom sij tam sim no. Muaj cov koom haum xws li Electronic Industry Association (EIA) thiab Telecommunication industries Association (TIA) uas teeb tsa cov qauv rau kev tsim cov cables thiab lwm yam cuab yeej siv hauv kev teeb tsa lub network. Qhov no ua kom muaj kev sib raug zoo ntawm cov cuab yeej muab los ntawm cov tuam txhab sib txawv, thiab tso cai rau kev hloov pauv cov ntaub ntawv zoo dua thiab du ntawm txoj hauv kev ntev thiab ntxiv rau cov ntaub ntawv zoo dua. Yav dhau los EIA pom zoo siv cov lus ua ntej RS ua ntej cables, thiab yog li lawv tau sau npe tias RS232 thiab RS485. RS tsuas yog txhais tau tias Cov Qauv Pom Zoo, tab sis tam sim no tau txais yuav yog siv EIA ua ntej siv RS.
Cov ntaub ntawv hloov pauv yog dav faib ua ib qho kawg thiab qhov sib txawv. RS232, uas yog txhais tau tias yog ib qho kawg tau tsim tawm hauv xyoo 1962, thiab txawm tias nws muaj kev txwv, tseem siv tau txog niaj hnub no. RS232 tso cai rau kev hloov cov ntaub ntawv ntawm qhov nrawm nrawm (txog 20K ntsis / sec) thiab luv luv (txog 50 ft).
Thaum cov ntaub ntawv hloov pauv yuav tsum muaj nyob rau qhov ntev, thiab tseem ntawm tus nqi nrawm dua, txoj kev xaus ib zaug ua pov thawj tias tsis muaj txiaj ntsig. Qhov no yog thaum sib txawv cov ntaub ntawv xa mus rau hauv daim duab vim nws muab kev ua tau zoo dua. Cov teeb liab no cuam tshuam qhov tsis zoo ntawm kev hloov hauv av thiab ua rau lub suab nrov ntawm lub network. RS422 tau tsim los ua kom tau raws li qhov yuav tsum tau ua, tab sis dhau sijhawm nws tau pom tias RS422 tsis tuaj yeem siv los tsim kom muaj qhov tseeb ntau qhov chaw network. Nkag mus rau RS485, uas ua tau raws li tag nrho cov kev xav tau ntawm lub network tiag tiag. RS485 qhia txog 32 tus neeg tsav tsheb thiab 32 tus neeg txais ntawm ib lub tsheb npav. Cov neeg tsav tsheb RS485 kuj muaj peev xwm daws tau qhov teeb meem ntawm cov ntaub ntawv sib tsoo thiab cov xwm txheej hauv tsheb npav.
Muaj ntau qhov sib txawv ntawm RS232 thiab RS485 thiab hom kev taw qhia yog qhov tseem ceeb ntawm lawv. Thaum RS485 sib npaug, RS232 tsis sib npaug. Nov yog saib ntawm qhov tshwj xeeb ntawm RS232 thiab RS485 uas qhia zaj dab neeg.
| Specifications | RS232 | RS485 |
| Kev Ua Haujlwm | Single end | Differential |
| No. ntawm cov tsav tsheb thiab cov neeg txais | 1 tus tsav tsheb, 1 tus txais | 32 tus tsav tsheb, 32 tus txais |
| Max. cable length | 50 ft | 4000 ft |
| Data rate | 20kb/s | 10Mb/s |
| Tsav tsheb tso zis voltage | +/-25V | -7V to +12V |
| Signal level(Loaded min) | +/-5V to +/-15V | +/-1.5 V |
| Signal theem (Unloaded Max) | +/-25V | +/-6V |
| Tsav tsheb thauj khoom impedance | 3k to 7k | 54 |
| Receiver input V range | +/-15V | -7 to +12V |
| Receiver input rhiab heev | +/-3V | +/-200mV |
| Receiver input resistance | 3k to 7k | Ntau tshaj 12k |
