Cov lus piav qhia ntxaws txog qhov hluav taws xob siv hauv RS485

1, Voltage ntau ntawm RS485
Tus qauv RS485 qhia qhov voltage ntau rau kev siv interface, feem ntau ntawm -7V thiab +12V. Qhov ntau qhov hluav taws xob no tso cai rau RS485 cov cim qhia kom muaj lub teeb liab txaus lub zog thaum lub sijhawm sib kis mus ntev, thaum tseem tiv thaiv qee qhov hluav taws xob cuam tshuam. RS485 interface txais ib txoj kev sib txawv ntawm cov teeb liab kis tau tus mob, qhov twg qhov sib txawv ntawm qhov sib txawv ntawm ob lub teeb liab kab sawv cev rau lub xeev cov ntsiab lus, tsis yog qhov tseeb voltage tus nqi ntawm ib kab teeb liab. Yog li ntawd, txawm hais tias muaj qhov sib txawv ntawm tus nqi hluav taws xob hauv kev siv tswv yim, tsuav yog qhov sib txawv ntawm qhov sib txawv ntawm ob lub teeb liab tseem tsis hloov pauv, lub ntsiab lus tseem ceeb tseem tuaj yeem txheeb xyuas tau.
2, Yog vim li cas rau xaiv no voltage ntau yam
Kev xaiv ntawm RS485 qhov hluav taws xob ntau ntawm -7V txog +12V feem ntau yog raws li cov kev xav hauv qab no:
Muaj peev xwm tiv thaiv kev cuam tshuam: Qhov ntau dua qhov hluav taws xob ua rau RS485 cov cim qhia kom zoo dua tiv thaiv hluav taws xob thiab cuam tshuam thaum sib kis. Qhov no yog qhov tseem ceeb tshwj xeeb rau kev siv RS485 interface nyob rau hauv kev lag luam ib puag ncig lossis thaj chaw uas muaj kev cuam tshuam ntawm electromagnetic siab.
Kev sib kis ntev ntev: Ib qho hluav taws xob ntau dua txhais tau hais tias lub teeb liab muaj tsawg attenuation hauv cable, txhawb kev sib kis ntev dua. Qhov no ua rau RS485 interface haum rau daim ntawv thov scenarios uas xav tau kev sib txuas lus ntev.
Kev sib raug zoo thiab kev ruaj ntseg: Qhov voltage ntau ntawm RS485 interface yog sib xws nrog lwm cov qauv kev sib txuas lus, xws li RS232 thiab RS422. Qhov no ua rau nws tuaj yeem siv ntau cov qauv kev sib txuas lus ib txhij hauv tib lub cev. Lub caij no, qhov ruaj khov voltage ntau kuj pab kom muaj kev ruaj ntseg thiab kev ntseeg siab ntawm kev sib txuas lus.
3, Kev sib piv nrog lwm cov qauv kev sib txuas lus
Piv rau lwm cov qauv kev sib txuas lus, qhov voltage ntau ntawm RS485 muaj qee qhov zoo. Piv txwv li, qhov voltage ntau siv los ntawm RS232 interface feem ntau yog nyob nruab nrab ntawm -15V thiab +15V. Txawm hais tias nws tseem tuaj yeem muab qhov muaj peev xwm tiv thaiv kev cuam tshuam, nws txoj kev sib kis tau luv luv. Lub TTL interface siv qhov hluav taws xob qis dua (feem ntau yog nruab nrab ntawm 0V thiab 5V) thiab muaj kev cuam tshuam rau lub suab nrov cuam tshuam thaum kis mus ntev. Hauv qhov sib piv, qhov hluav taws xob ntau ntawm RS485 tswj kev muaj peev xwm tiv thaiv kev cuam tshuam thaum tseem txhawb kev sib kis ntev dua.
4, Cov yam ntxwv uas yuav tsum tau xav txog hauv kev siv tswv yim
Hauv kev siv tswv yim, cov hauv qab no yuav tsum tau txiav txim siab thaum xaiv thiab siv RS485 interface:
Kev xaiv Cable: Xaiv cov kab tsim nyog thiab cov kev qhia tshwj xeeb raws li kev sib kis deb thiab cov teeb liab zoo yuav tsum tau ua. Impedance matching thiab teeb liab amplification ntsuas tej zaum yuav xav tau rau kev sib kis mus ntev kom tswj tau cov teeb liab zoo.
Terminal ntaus ntawv sib piv: xyuas kom meej tias RS485 interface ntawm cov khoom siv davhlau ya nyob twg (xws li khoos phis tawj, PLCs, thiab lwm yam) cuam tshuam cov yam ntxwv hluav taws xob ntawm cov cables kom tsis txhob muaj kev sib txuas lus tsis zoo.
Lub zog ruaj khov: Txhawm rau kom ntseeg tau tias kev ua haujlwm ruaj khov ntawm RS485 interface, lub zog ruaj khov yuav tsum tau muab. Hauv ib puag ncig uas muaj kev hloov pauv ntawm lub zog tseem ceeb, kev ntsuas hluav taws xob ntxiv yuav tsim nyog.
Electromagnetic cuam tshuam kev tiv thaiv: Thaum siv RS485 interface nyob rau hauv ib puag ncig uas muaj kev cuam tshuam ntawm electromagnetic cuam tshuam, tsim nyog yuav tsum tau siv cov kev tiv thaiv electromagnetic cuam tshuam, xws li siv cov shielded cables, nce grounding, thiab lwm yam.
Hauv cov ntsiab lus, qhov hluav taws xob ntau ntawm -7V rau+12V siv los ntawm RS485 interface yog xaiv raws li nws muaj peev xwm tiv thaiv kev cuam tshuam zoo thiab cov yam ntxwv sib kis mus ntev. Hauv kev siv tswv yim, peb yuav tsum teeb tsa thiab siv RS485 interface tsim nyog raws li cov kev xav tau tshwj xeeb thiab ib puag ncig kom ntseeg tau tias kev sib txuas lus ruaj khov thiab kev ntseeg tau.