Muaj ntau yam cuam tshuam rau kev ua haujlwm ntawm CAN
1. Kev khiav hauj lwm voltage ntau ntawm CAN network
Ua haujlwm voltage:CAN network feem ntau ua haujlwm ntawm 5V qib, thiab qhov tshwj xeeb kev ua haujlwm voltage ntau yog 4.5V txog 5.5V. Lub CAN transceiver yog lub luag haujlwm rau kev hloov pauv lub cev theem teeb liab mus rau CAN tsheb npav tus qauv theem thiab tseem ceeb heev rau kev xa cov teeb liab kom raug.
Lub zog hluav taws xob:Lub hwj chim mov voltage ntawm lub transceiver feem ntau yog 3.3V lossis 5V, nyob ntawm seb tus qauv tsim ntawm lub cuab yeej. Nws yuav tsum tau muab sau tseg tias kev ruaj ntseg ntawm lub hwj chim mov voltage yog ib qho tseem ceeb heev rau kev ntseeg siab ntawm CAN teeb liab, thiab voltage fluctuations yuav ua rau kev sib txuas lus yuam kev.
2. Cable kuj thiab capacitance tsis thiab ib puag ncig yuav tsum tau ntawm CAN network
Cable impedance:Tus yam ntxwv impedance ntawm CAN tsheb npav feem ntau yog 120 ohms, uas phim lub davhlau ya nyob twg tiv thaiv kom tsis txhob cuam tshuam cov teeb liab. Nyob rau hauv daim ntawv thov ntawm lub tsheb fais fab, lub tsheb npav CAN yuav tsum tau siv tsheb-tus qauv twisted khub cables kom tswj tau cov impedance zoo ib yam thiab txo cov electromagnetic cuam tshuam.
Capacitive load:Qhov siab tshaj plaws capacitive load ntawm lub npav yuav tsum tsawg dua 200 pF. Tshaj dhau lub peev xwm load yuav ua rau lub sijhawm nce thiab poob ntawm lub teeb liab, yog li cuam tshuam rau kev ncaj ncees ntawm lub teeb liab.
Inductive nyhuv:Hauv cov tsheb hluav taws xob, kev xaim ntawm cov cables tuaj yeem qhia cov nyhuv inductive, uas feem ntau txo qis los ntawm cov txheej txheem xaim tsim nyog thiab ntxiv cov ntsiab lus lim.
Cable ntev:Qhov siab tshaj plaws ntev ntawm CAN network yog 40 meters (ntawm 1 Mbps). Yog tias qhov ntev ntawm cable yuav tsum tau txuas ntxiv, tus nqi sib txuas lus yuav tsum raug txo kom ntseeg tau tias cov teeb liab ncaj ncees. Piv txwv li, ntawm 125 kbps, qhov siab tshaj plaws cable ntev tuaj yeem ncav cuag 500 meters.
Ua haujlwm ib puag ncig:CAN tsheb npav cables yuav tsum muaj peev xwm ua haujlwm tau zoo tshaj qhov kub ntawm lub tsheb (feem ntau yog -40 degree rau +85 degree , thiab mus txog +125 degree nyob rau hauv huab cua txias). Kev xaiv ntawm cov cables thiab tsim cov sheaths yuav tsum coj mus rau hauv tus account raws li qhov yuav tsum tau muaj xws li kub tsis kam, roj kuj, thiab UV tsis kam.
3. Kev cuam tshuam thiab hluav taws xob hluav taws xob ntawm kev sib txuas lus transceiver nodes
Electromagnetic cuam tshuam (EMI) kev tswj hwm: Qhov chaw electromagnetic hauv lub tsheb hluav taws xob yog qhov nyuaj vim muaj cov motors thiab cov khoom siv hluav taws xob muaj zog. CAN transceivers thiab tsheb npav muaj kev cuam tshuam rau EMI, uas tuaj yeem ua rau kev sib txuas lus yuam kev lossis txawm tias lub cev tsis ua haujlwm.
Anti-interference tsim: Shielded cable: Siv shielded twisted khub (STP) los yog shielded twisted khub (F/UTP) los txo qhov cuam tshuam ntawm electromagnetic hluav taws xob thiab sab nraud cuam tshuam. Terminal Resistance: Kho qhov teeb meem tsis raug (feem ntau yog 120 ohms) ua lub luag haujlwm tseem ceeb hauv kev cuam tshuam cov teeb liab cuam tshuam thiab cuam tshuam.
Lim:Ntxiv cov hom chokes thiab decoupling capacitors rau cov qauv tsim los lim cov kev cuam tshuam ntau zaus.
Electromagnetic tawg:Cov hluav taws xob hluav taws xob hluav taws xob ntawm CAN network yuav tsum ua raws li cov qauv kev lag luam tsheb, xws li CISPR 25 (kev tiv thaiv hluav taws xob thiab cuam tshuam rau cov khoom siv hluav taws xob hauv tsev). Qhov kev xav tau hluav taws xob tshwj xeeb feem ntau yog qib tsis tshaj 30 dBμV / m (hauv 30 MHz txog 1 GHz zaus band), thiab tus nqi tshwj xeeb txawv nyob ntawm qhov chaw thov tsheb.
4. Kev tshuaj xyuas qhov tsis raug thiab kev daws teeb meem
Hom txhaum:
Bus qhib lossis luv Circuit Court:Qhov no tej zaum yuav tshwm sim los ntawm lub cev puas tsuaj los yog xoob connectors, uas yuav ua rau cov node tsis muaj peev xwm sib txuas lus.
Terminal kuj tsis sib haum:Kev ploj lossis tsis raug tus nqi ntawm lub davhlau ya nyob twg tiv thaiv yuav ua rau muaj teeb meem cuam tshuam, ua rau kev sib txuas lus yuam kev.
Lub zog tsis zoo ntawm cov khoom siv hluav taws xob:tsis ruaj tsis khov lossis tsis tshua muaj hluav taws xob tsawg dhau ntawm CAN transceiver yuav ua rau teeb liab distortion thiab kev sib txuas lus cuam tshuam.
EMI cuam tshuam:Kev cuam tshuam los ntawm cov khoom siv hluav taws xob sab nraud muaj zog lossis cov khoom siv hluav taws xob sab hauv yuav ua rau pob ntawv poob lossis CRC yuam kev.
Txoj kev daws teeb meem:
Kev tshuaj xyuas lub cev:Xyuas seb qhov kev sib txuas ntawm cable, lub davhlau ya nyob twg tsis kam thiab lub zog hluav taws xob hluav taws xob ua tau raws li cov qauv. Kev kuaj Oscilloscope: Siv lub oscilloscope txhawm rau kuaj cov nthwv dej ntawm CAN_H thiab CAN_L los saib seb puas muaj cov teeb liab txawv txav, siab dhau lossis qis dhau.
Kev ntsuas hluav taws xob:Tshawb xyuas lub zog hluav taws xob hluav taws xob ntawm CAN transceiver los xyuas kom meej tias nws nyob hauv qhov kev ua haujlwm ib txwm muaj (piv txwv li, 4.5V txog 5.5V).
EMI tsom xam:Siv lub spectrum analyzer txhawm rau txheeb xyuas qhov cuam tshuam ntawm electromagnetic cuam tshuam hauv ib puag ncig thiab siv kev tiv thaiv lossis kev ntsuas kev cais tawm.
Cov nqi siv tshwj xeeb
Kev khiav hauj lwm voltage ntau: 4.5V rau 5.5V.
Cable yam ntxwv impedance: 120 ohms.
Qhov siab tshaj plaws capacitive load: <200 pF.
Qhov siab tshaj plaws cable ntev: 40 meters ntawm 1 Mbps; 500 meters ntawm 125 kbps.
Kev xav tau hluav taws xob hluav taws xob: Raws li CISPR 25 tus qauv, qib tsis tshaj 30 dBμV / m.
Los ntawm kev soj ntsuam saum toj no, peb tuaj yeem pom tias qhov kev ruaj ntseg ntawm CAN network nyob ntawm ntau yam, suav nrog voltage, cable tsis thiab electromagnetic compatibility (EMC). Tsim nyog tsim thiab kev daws teeb meem yog qhov tseem ceeb los xyuas kom meej tias kev ua haujlwm txhim khu kev qha ntawm lub tsheb fais fab CAN network.
