Kungani 4-20mA?

Yini i-4-20mA?

Izinga lesignali le-4-20mA DC (1-5V DC) lichazwa yi-International Electrotechnical Commission (IEC) futhi lisetshenziselwa amasignali e-analog ezinhlelweni zokulawula inqubo.

Ngokuvamile, isignali yamanje yezinsimbi namamitha isethelwe ku-4-20mA, ne-4mA emele ubuncane bamanje kanye no-20mA omele umkhawulo wamanje.

Kungani okukhiphayo kwamanje?

Ezilungiselelweni zezimboni, ukusebenzisa i-amplifier yesignali ukuze kulungiswe futhi kudluliselwe amasignali ebangeni elide usebenzisa amasignali kagesi kungaholela ezinkingeni ezimbalwa. Okokuqala, amasignali kagesi adluliswa phezu kwezintambo angaba lula ekuphazamisekeni komsindo. Okwesibili, ukumelana nokusabalalisa kwemigqa yokudlulisela kungabangela ukwehla kwe-voltage. Okwesithathu, ukunikeza amandla ku-amplifier yesignali ensimini kungaba inselele.

Ukubhekana nalezi zinkinga futhi kuncishiswe umthelela womsindo, i-current isetshenziselwa ukudlulisa amasignali ngoba ayizweli kakhulu emsindweni. Iluphu yamanje engu-4-20mA isebenzisa i-4mA ukumela isignali enguziro kanye no-20mA ukuze imele isignali yesilinganiso esigcwele, namasignali angaphansi kuka-4mA nangaphezulu kuka-20mA asetshenziselwa ama-alamu amaphutha ahlukahlukene.

Kungani sisebenzisa i-4-20mA DC (1-5V DC)?

Izinsimbi zasensimini zingasebenzisa isistimu yezintambo ezimbili, lapho ukunikezwa kwamandla nomthwalo kuxhunywe khona ochungechungeni ngephoyinti elivamile, futhi izintambo ezimbili kuphela ezisetshenziselwa ukuxhumana kwesignali kanye nokunikezwa kwamandla phakathi kwesidlulisi sensimu kanye nethuluzi legumbi lokulawula. Ukusebenzisa isignali engu-4mA DC njengoba iqala lamanje linikeza ukusebenza okumile kusithumeli, kanye nokusetha iphoyinti likagesi elinguziro ku-4mA DC, elingahambelani nephoyinti lomshini elinguziro, kuvumela ukutholwa kwamaphutha njengokulahleka kwamandla nokunqamuka kwentambo. . Ukwengeza, isistimu yezintambo ezimbili ilungele ukusebenzisa izithiyo zokuphepha, ezisiza ekuvikelweni kokuqhuma.

Amathuluzi egumbi lokulawula asebenzisa ukudluliswa kwesignali ye-voltage-parallel, lapho amathuluzi esistimu yokulawula efanayo abelana ngetheminali evamile, okuyenza ilungele ukuhlolwa kwensimbi, ukulungiswa, ukuxhumana kwekhompuyutha, namadivayisi e-alamu.

Isizathu sokusebenzisa i-4-20mA DC yokuxhumana kwesignali phakathi kwezinsimbi zasensimini nezinsimbi zegumbi lokulawula ukuthi ibanga phakathi kwenkundla negumbi lokulawula lingaba elibalulekile, okuholela ekuphikisaneni kwekhebula okuphezulu. Ukudlulisa amasignali kagesi ebangeni elide kungabangela amaphutha abalulekile ngenxa yokwehla kwamandla kagesi okubangelwa ukumelana nekhebula kanye nokumelana nokokufaka kwensimbi eyamukelayo. Ukusebenzisa isignali yomthombo yamanje eqhubekayo yokudlulisela kude kuqinisekisa ukuthi i-current ku-loop ihlala ingashintshile kungakhathaliseki ubude bekhebula, okuqinisekisa ukunemba kokudlulisela.

Isizathu sokusebenzisa isignali ye-DC engu-1-5V ukuze kuxhunywe phakathi kwamathuluzi egumbi lokulawula ukwenza lula izinsimbi eziningi ezithola isignali efanayo kanye nokusiza ekufakeni izintambo nokwenza izinhlelo ezihlukahlukene zokulawula eziyinkimbinkimbi. Uma umthombo wamanje usetshenziswa njengesignali yokuxhumana, lapho amathuluzi amaningi athola isignali efanayo ngesikhathi esisodwa, ukumelana kwawo kokokufaka kufanele kuxhunywe kuchungechunge. Lokhu kuzodlula umthamo wokulayisha wethuluzi lokudlulisa, futhi amandla esiginali aphansi kwezinto ezitholwayo azohluka, kwethule ukuphazamiseka futhi kuvimbele ukunikezwa kwamandla okumaphakathi.

Ukusebenzisa isignali yomthombo kagesi ekuxhumekeni kudinga ukuguqula isignali yamanje esetshenziselwa ukuxhumana nezinsimbi zasensimini ibe isignali kagesi. Indlela elula ukuxhuma i-resistor evamile engu-250-ohm ochungechungeni kumjikelezo wamanje wokudlulisa, ukuguqula i-4-20mA DC ibe yi-1-5V DC. Ngokuvamile, lo msebenzi wenziwa nge-transmitter.

Lo mdwebo usebenzisa i-resistor engu-250-ohm ukuze uguqule isignali yamanje engu-4-20mA ibe isignali kagesi engu-1-5V, bese usebenzisa isihlungi se-RC kanye ne-diode exhunywe kuphinikhodi yokuguqula ye-AD ye-microcontroller.

“Lapha kunamathisele umdwebo wesekethe olula wokuguqula isignali yamanje engu-4-20mA ibe isignali kagesi:

Kungani i-transmitter ikhethwa ukusebenzisa isignali ye-4-20mA DC ukuze idluliselwe?

1. Ukucatshangelwa kokuphepha kwezindawo eziyingozi: Ukuphepha ezindaweni eziyingozi, ikakhulukazi kumathuluzi angaqhumisi, kudinga ukunciphisa ukusetshenziswa kwamandla amile naguqukayo adingekayo ukuze kugcinwe ithuluzi lisebenza. Ama-Transmitter akhipha isignali evamile engu-4-20mA DC ngokuvamile asebenzisa amandla kagesi angama-24V DC. Ukusetshenziswa kwamandla kagesi e-DC ngokuyinhloko kungenxa yokuthi iqeda isidingo sama-capacitor amakhulu nama-inductors futhi igxile kumandla asabalalisiwe kanye ne-inductance yezintambo zokuxhuma phakathi kwe-transmitter kanye nethuluzi legumbi lokulawula, eliphansi kakhulu kunomshini wokuthungela wegesi ye-hydrogen.

2. Ukudluliselwa komthombo wamanje kukhethwa kunomthombo wamandla kagesi: Ezimeni lapho ibanga phakathi kwenkundla negumbi lokulawula lilikhulu, ukusetshenziswa kwamasignali omthombo wamandla kagesi ekudluliselweni kungase kuveze amaphutha abalulekile ngenxa yokwehla kwamandla kagesi okubangelwa ukumelana nekhebula nokokufaka. ukumelana kwethuluzi elamukelayo. Ukusebenzisa isignali yamanje yomthombo wokudlulisela kude kuqinisekisa ukuthi i-current ku-loop ihlala ingashintshi, kungakhathaliseki ubude bekhebula, ngaleyo ndlela igcina ukunemba kokudlulisela.

3. Ukukhethwa kwe-20mA njengobukhulu bamanje: Ukukhethwa kwesilinganiso esiphezulu samanje esingu-20mA kusekelwe ekucatshangelweni kokuphepha, ukusebenza, ukusetshenziswa kwamandla, kanye nezindleko. Amathuluzi angaqhumisi angasebenzisa i-voltage ephansi kanye namandla aphansi. I-4-20mA yamanje kanye ne-24V DC iphephile ukusetshenziswa uma kukhona amagesi avuthayo. I-ignition current yegesi ye-hydrogen ene-24V DC ingu-200mA, iphakeme kakhulu kuno-20mA. Ukwengeza, izinto ezifana nebanga phakathi kwamathuluzi esayithi lokukhiqiza, umthwalo, ukusetshenziswa kwamandla, izidingo zengxenye ye-elekthronikhi, kanye nezidingo zokuphakelwa kwamandla ziyacatshangelwa.

4. Ukukhethwa kwe-4mA njengendawo yokuqala yamanje: Ama-transmitter amaningi akhipha i-4-20mA asebenza ohlelweni lwezintambo ezimbili, lapho amandla okunikezwa kwamandla nomthwalo kuxhunywe ochungechungeni ngephuzu elivamile, futhi izintambo ezimbili kuphela ezisetshenziselwa ukuxhumana kwesignali. kanye nokunikezwa kwamandla phakathi kwe-transmitter yasendle kanye nethuluzi legumbi lokulawula. Ukukhethwa kwe-4mA yokuqala yamanje kubalulekile ukuze isekethe yesidluliseli sisebenze. I-4mA yokuqala yamanje, engahambelani nephoyinti likaziro, inikeza "iphoyinti eliziro elisebenzayo" elisiza ukukhomba amaphutha afana nokuphelelwa amandla nokunqamuka kwekhebula.

Ukusetshenziswa kwamasiginali we-4-20mA kuqinisekisa ukuthikamezeka okuncane, ukuphepha, nokuthembeka, okuyenza ibe yindinganiso eyamukelwa kabanzi ezinhlelweni zezimboni. Kodwa-ke, amanye amafomethi esignali okukhiphayo, njenge-3.33mV/V, 2mV/V, 0-5V, kanye ne-0-10V, nawo asetshenziselwa ukuphatha kangcono amasignali enzwa nokusekela amasistimu okulawula ahlukahlukene.