RS485 yog dab tsi thiab yuav ua li cas 120 ohm sib piv resistor ntawm RS485 txuas?
Lub tsheb npav RS485 yog tus qauv uas txhais cov yam ntxwv hluav taws xob ntawm cov neeg tsav tsheb thiab cov neeg txais kev sib raug zoo hauv kev sib npaug ntawm cov ntsiab lus digital. Nws txais yuav ib nrab-duplex ua haujlwm hom thiab txhawb nqa cov ntaub ntawv sib txuas lus ntau. Lub RS485 tsheb npav network topology feem ntau siv lub tsheb npav-hom qauv nrog lub davhlau ya nyob twg txuam. Ntawd yog, lub tsheb npav yog siv los txuas txhua qhov ntawm cov koob. RS485 txais kev sib npaug sib kis thiab kev txais tos sib txawv, yog li nws muaj peev xwm tiv thaiv kev cuam tshuam ntau hom. Tsis tas li ntawd, lub tsheb npav transceiver muaj qhov rhiab heev thiab tuaj yeem ntes cov hluav taws xob tsawg li 200mv, yog li cov teeb liab kis tau zoo tuaj yeem rov qab tau los ntawm mais deb. Daim ntawv thov ntau tshaj plaws ntawm RS485 yog kev sib txuas lus ntawm programmable logic controllers nyob rau hauv kev lag luam ib puag ncig.
Thaum qee cov neeg siv khoom sim RS485 cov khoom siv hauv chaw ua haujlwm, cov ntaub ntawv kev sib txuas lus zoo li qub. Txawm li cas los xij, thaum siv hauv cov chaw lag luam, tej zaum yuav muaj qhov xwm txheej uas kev sib txuas lus tsis ua tiav. Qhov teeb meem no tshwm sim li cas?
Thaum kuaj hauv chaw ua haujlwm, cov hlau feem ntau siv tsuas yog ob peb meters. Ntawm qhov xwm txheej, nws yuav yog ob peb puas meters ntawm cov xaim, txawm hais tias nws yog cov hlau thaiv, nws tseem yuav yog vim tias qib RS485 tsis sib xws, ua rau kev sib txuas lus tsis tiav. Tom qab ntxiv 120 ohm resistors ntawm ob qho kawg, qhov teeb meem daws tau zoo kawg nkaus.
RS485 chips ntawm cov khoom siv sib txawv feem ntau sib txawv, thiab muaj cov chips ntawm ntau hom kev thauj khoom, uas feem ntau tsis pom ncaj qha rau cov engineers. Yog li ntawd yog hais tias, qhov siab tshaj plaws ntawm cov khoom sib txuas rau cov khoom siv sib txawv ntawm lub tsheb npav tsis paub tseeb. Rau tib lub xov tooj ntawm kev sib txuas ntawm cov cuab yeej, thov xa mus rau cov lus piav qhia ntawm lub cuab yeej.
