Binciken Scan Time: Dalilin da Ya Sa Sakamakon Auna Yake Bambanta da Datasheets
Datasheets suna cewa 0.08 µs don basic logic. Amma ainihin scan time ya haɗa da sabunta I/O image, sarrafa sadarwa, da nauyin operating system. A gwaje-gwajen filin tare da PM564 CPU, shiri mai ladder rungs 200 da digital I/O 64 ya samar da matsakaicin scan time na 1.8 ms. Irin wannan shirin tare da analog inputs 8 ya ƙaru zuwa 2.4 ms saboda jinkirin ADC conversion.
Rarraba tasks yana da tasiri kai tsaye kan jitter. Saka high-speed counting logic a cikin cyclic interrupt na 1 ms. Motsa sabunta bayanan HMI zuwa task na 50 ms. Wata layin marufin kaya ta rage kuskuren matsayi daga 3 mm zuwa 0.5 mm bayan raba tasks ɗin daidai. Injiniyoyi ya kamata koyaushe su yi amfani da kayan aikin auna aiki a cikin Automation Builder a lokacin ci gaba.
Saitin Interrupt Task don Tsarin da Suke da Sauri
AC500-eCo na goyon bayan cyclic interrupt tasks har zuwa 8. Kowace task tana aiki ne dabam da main scan. Don injin cike kwalabe da ke sarrafa kwalabe 120 a minti, a saita interrupt na 2 ms don karanta flowmeter pulse counter. Shirin main zai ƙididdige jimlar batch kowane 50 ms. Wannan hanyar tana hana asarar pulses a lokacin babban nauyin sadarwa.
Kuskure gama-gari yana haɗa da saka function blocks da yawa a cikin interrupt tasks. Kowane PID block yana ƙara kusan 0.05 ms. PID blocks guda uku a cikin task na 1 ms suna cinye kashi 15% na lokacin da ake da shi. Motsa lissafe-lissafen da ba su da muhimmanci zuwa tasks masu jinkiri.
Zane na Power Supply don Aiki Mai Dorewa 24/7
Raguwar volt suna haifar da yawan sake kunnawar PLC fiye da ainihin lalacewar kayan aiki. AC500-eCo tana karɓar 19.2V zuwa 28.8V DC (ciki har da ripple). Duk da haka, gwaje-gwajen filin sun nuna cewa idan volt ta faɗi ƙasa da 20V na kawai 5 ms, ana samun brownout reset. Saboda haka, a zaɓi na’urar wuta da ƙarin ƙarfin 30%. Don tsarin da ke ja 1A na matsakaici, a yi amfani da wutar 1.5A.
Ƙara capacitor 10,000 µF a fadin terminals na 24V idan PLC na raba wutar lantarki da motor contactors. A wani tsarin conveyor, faduwar contactor ta haifar da raguwar volt na 40 ms. Capacitor ɗin ya riƙe volt sama da 21V, ya hana PLC ta sake kunnawa. Wannan sashi mai kuɗin $5 ya ceci sa’o’i shida na binciken matsala.
Kare Inrush Current da Zabin Fuse
CPU tana ja 250 mA na yau da kullum amma tana kai kololuwa na 2.5A na tsawon 2 ms a lokacin kunnawa. Wutar fuse mai saurin konewa (fast-blow) na iya katsewa ba daidai ba. Koyaushe a saka slow-blow 2A fuse. Yi amfani da na’urar wutar lantarki 24V DC da ke da kariyar iyakar ƙarfi (active current limiting). Yawancin na’urorin wuta masu arha suna rage volt a lokacin overload, suna haddasa rawar wuta (oscillations). Maimakon haka, zaɓi na’urar wuta da ke da yanayin constant current.
Kammala fitowar wutar lantarki da fiyus PTC mai sake saiti 0.5A ga kowace ƙungiyar modulen I/O. Wannan kariyar ta gida tana hana na’urar firikwensin guda ɗaya da ta yi gajeriyar hanya ta kashe dukkan PLC. Bayanai daga filin sun nuna cewa fiyus na gida suna rage lokacin binciken matsala da kashi 70%.
Tacewar shigarwar dijital: Cire tsallen tuntuɓa ba tare da rasa gefuna (edges) ba
Maɓallan inji da relays suna haifar da tsallen tuntuɓa (contact bounce) na tsawon 5 ms zuwa 15 ms. Ana saita matatar shigarwa ta AC500-eCo daga 0.1 ms zuwa 32 ms. Ga maballan tura (push buttons) da na’urorin iyaka (limit switches), saita matatar zuwa 10 ms. Wannan yana ƙin tsallen amma har yanzu yana kama saurin motsin hannu. Ga bugun encoder ko kirga mai sauri, saita matatar zuwa 0.1 ms.
Wani nazarin lamari daga layin cika kwantaina ya nuna yarjejeniyar canjin (trade-off). A farko, injiniyoyi sun saita tacewa 10 ms a kan dukkan shigarwa. Na’urorin gano kasancewar kwalabe kusa da injin cika suna fitar da bugun 8 ms. PLC ta rasa kashi 2% na kwalabe. Sake saita shigarwar masu sauri kawai zuwa tacewar 0.5 ms ya kawar da duk asarar yayin da har yanzu an bar “debounce” na maballan yana aiki.
Saita matatun shigarwa ta amfani da software
Automation Builder yana ba da daidaita tacewa (filter) na kowane tashar daban. Buɗe shafin saitin I/O na kowane modulen shigarwa na dijital. Zaɓi tashar sannan ka zaɓi lokacin tacewa. Canjin yana fara aiki nan da nan bayan sauke shirin. Ba a buƙatar sauya kayan aiki. Don nesa I/O ta fieldbus, saitin tacewa yana kan modulen nesa. Duba takardar umarnin takamaiman module don irin zaɓuɓɓukan da ake da su.
Dabarun yin ƙasa da ke kawar da karkacewar siginar analog
Siginar analog suna da saurin kamuwa da bambancin ƙarfin ƙasa (ground potential differences). Modulen analog na AC500-eCo suna auna wuta tsakanin tashar shigarwa da tashar gama gari (COM). Idan na’urori da yawa suna da tushe na ƙasa daban-daban, auna siginar tana karkacewa. Wani tashar kula da ruwa ta lura da karkacewar 0.5V a kan madauki 4-20mA. Asalin matsalar shi ne bambancin ƙasa 0.3V tsakanin PLC da mai watsawa (transmitter).
Yi amfani da “single-point star ground”. Haɗa duk dawowar 24V DC zuwa mashin dogon ƙarfe guda ɗaya. Haɗa ƙasan aikin PLC (functional ground) zuwa wannan mashin ɗin ma. Don siginar analog masu nisan tafiye (fiye da mita 50), yi amfani da masu watsawa (transmitters) masu keɓewa ko masu keɓe sigina (signal isolators). Wannan mafita ta kawar da matsalar karkacewar sigina gaba ɗaya.
Ka’idojin kammala garkuwa ga keblolin sigina na analog
Haɗa garkuwar kebul ne kawai a ɓangarən PLC. Bar garkuwar tana lilo a ɓangarən na’urar firikwensin. Wannan yana hana “ground loop”. Yi amfani da kebul mai ɗaure igiyoyi biyu (shielded twisted-pair) da garkuwa 100%. Wayoyin “drain” su zama gajeru ƙwarai – ƙasa da 5 cm daga matse garkuwa zuwa ƙugiyar ƙasa. A wani shigarwa, wayar drain mai tsawon 15 cm ta tattara isasshen EMI har ta haifar da girgizar sigina kashi 2%. Rage tsawon zuwa 3 cm ya rage girgizar zuwa 0.2%.
Modbus RTU: Yarjejeniyar tsakanin ƙimar baud da tsawon kebul
Dogayen igiyoyi suna buƙatar ƙananan baud rate. A 19200 baud, sadarwa mai dogaro tana kaiwa zuwa mita 300 da igiya mai kyau. A 115200 baud, matsakaicin nisa yana sauka zuwa mita 50. Wani masana'antar sinadarai ta haɗa ma'aunin kwarara guda takwas a kan igiyar RS-485 mai tsawon mita 250. Gudanar da su a 9600 baud ya haifar da kuskure sifili a cikin watanni shida. Gwada 38400 baud ya jawo kuskuren CRC 5%.
Majinyatan ƙarshen waya (termination resistors) wajibi ne. Sanya majinyacin 120 ohm a fadin tashoshin Data+ da Data- a ƙarshen biyu na bus. Masu injiniya da dama suna manta da majinyacin ƙarshen na'ura ta ƙarshe. Wannan kura-kurar tana haddasa maida sako baya (reflections) da lokutan katsewar sadarwa lokaci-lokaci. Wata layin marufi tana samun gaza sadarwa ba-zata kusan a kowace awa biyu. Ƙara majinyacin ƙarshen da ya ɓace ya magance matsalar gaba ɗaya.
Lambobin Kuskuren Modbus da Ma'anoninsu
Code 01 (Illegal Function) yana bayyana ne idan bawan na'ura bai tallafi umarnin da aka nema ba. Yi amfani da function codes 03 (read holding registers) da 06 (write single register) domin mafi girman dacewa. Code 02 (Illegal Data Address) yana nufin adireshin rajista ya fita daga kewayo. Koyaushe a ware toshe rajistoci 100 da ke jere domin amfani na gama-gari. Code 03 (Illegal Data Value) yana nuna ƙima da ta fita daga iyakokin da aka yarda da su, misali rubuta 300 zuwa rajista na 0-255.
Daidaita Zagayen PID ba tare da Auto-Tune ba a Tsaruka Masu Sauri
Auto-tune baya aiki da kyau ga tsaruka da ke da dead time ƙasa da 200 ms. Don sarrafa matsa lamba da kwarara, daidaitawa da hannu kan fi bada sakamako mai kyau. Da fari, saita Ti zuwa mafi girma kuma Td zuwa sifili. Ƙara Kp har sai tsarin yana yin girgiza ba tare da tsayawa ba. Rubuta lokacin girgizar (Pu) da kuma gain a lokacin girgiza (Ku). Sa'an nan a yi amfani da ƙa'idodin Ziegler-Nichols: Kp = 0.45 * Ku, Ti = Pu / 1.2, Td = Pu / 8.
Wani amfani da injin latsawa na na'ura mai ruwa (hydraulic press) ya nuna wannan hanyar. Auto-tune ya samar da 40% overshoot da lokacin daidaituwa na 800 ms. Daidaitawa da hannu ta amfani da hanyar Ziegler-Nichols ta rage overshoot zuwa 8% kuma lokacin daidaituwa zuwa 250 ms. Sakamakon haka, lokacin zagayen aikin injin latsawar ya inganta da 15%.
Anti-Windup da Iyakokin Fitarwa
Taruwar integrator (integrator windup) na faruwa ne idan fitarwa ta kai iyakar jiki amma kuskuren ya ci gaba da kasancewa. Bulokin PID_CONTROL yana ƙunshe da fasalin anti-windup ta hanyar shigarwar Y_MANUAL. Saita Y_HIGH_LIMIT da Y_LOW_LIMIT zuwa ainihin kewayon bawul ko na'urar motsawa. Ga bawul da ke buɗewa daga 0% zuwa 100%, a saita iyakoki daidai. Idan babu iyakoki, integrator zai ci gaba da tarawa ya wuce 100%. Lokacin da kuskuren ya juya akasin haka, fitarwar tana ɗaukar lokaci mai yawa kafin ta dawo. Wani madauki na sarrafa zafin jiki ya ɗauki mintuna 12 kafin ya farfado daga windup. Ƙara iyakoki ya rage lokacin farfadowa zuwa daƙiƙa 90.
Aikace-aikacen Gaskiya: Haɗaɗɗen Bel na Jigila tare da Na'urorin Gano Shiga guda Shida
Wani cibiyar kayan jigila (logistics center) tana buƙatar haɗa layukan bel guda shida zuwa babban layi guda ɗaya. Kowace na'urar gano shigar kaya (induction sensor) tana gano akwatuna a gudun bel na mita 2 a daƙiƙa. AC500-eCo PM564 yana karanta na'urori shida kuma yana sarrafa ƙofofin haɗawa. Tazarar tsakanin akwatuna ita ce 500 mm. PLC ɗin dole ne ya yanke shawarar tsarin haɗawa a cikin 50 ms domin kauce wa karo.
Injiniyoyi sun daidaita ayyuka na katsewa (cyclic interrupt tasks) guda uku. Aikin 5 ms yana karanta duk na'urori masu auna sassa shida kuma yana ajiye lokutan da aka karanta su (timestamps). Aikin 20 ms yana lissafa matsayin akwatuna bisa gudun bel. Aikin 100 ms yana sarrafa na'urorin buɗe-kulle ƙofofi (gate actuators). Wannan tsari ya cimma haɗa akwatuna ba tare da karo ba kashi 100% a kan akwatuna 500,000. Tsohon mai kula da tsarin, wanda yake amfani da bincike guda ɗaya na 50 ms, yana haifar da karo kashi 0.3%.
Aikace-aikacen Gaskiya: Saka Sinadarai da Famfun Peristaltic Huɗu
Wani masana'antar tace ruwa tana ƙara sinadarai huɗu a cikin tankin gaurayawa. Kowanne famfo yana aiki da sauri daban-daban da ake sarrafawa da fitarwa analog 4-20mA daga AC500-eCo. Ma'aunin gudu (flowmeters) suna ba da martani 4-20mA. PLC ɗin yana gudanar da zagaye huɗu na PID masu zaman kansu don kiyaye ƙimar da aka sa a matsayin ma'auni.
Injinia mai kula da tsari ya daidaita kowane madauki da hannu ta amfani da hanyar Ziegler-Nichols. Famfo 1 (mai saurin amsawa) ya cimma daidaitaccen iko da Kp=1.2, Ti=0.8s, Td=0.2s. Famfo 4 (mai jinkirin amsawa saboda dogon bututu) ya buƙaci Kp=0.6, Ti=5.0s, Td=1.2s. Amfanin sinadarai ya ragu da 11% idan aka kwatanta da tsohuwar hanyar kunna-kashe (on-off control). A shekara ana ajiye dala $18,000 a cikin kuɗin sinadarai kaɗai.
Aikace-aikacen Gaskiya: Na'urar Biyayya wa Rana (Solar Tracker) da Ikon Baturi 24V
Wani tsarin hasken rana na waje da grid yana amfani da AC500-eCo PM554 don bin rana a kusurwoyi biyu (dual-axis tracking). PLC ɗin yana aiki ne da bankin baturi 24V da ake caji da panalan hasken rana. An auna cin wuta 3.8W ciki har da na'urori biyu masu auna haske na analog da masu tuƙa na'urorin motsi guda biyu. Tsarin yana farkawa duk bayan daƙiƙa 10, yana lissafa matsayin rana, sannan yana motsa na'urorin motsi idan an buƙata. A tsakanin motsi, PLC ɗin yana shiga yanayin idle inda yake jan wuta 1.2W kaɗai.
Bayan watanni 18 na aiki, PLC ɗin bai yi sake kunnawa ba (reset) kuma babu kuskuren lissafin logic kwata-kwata. Bankin baturin ya kiyaye wutar lantarki sama da 23.5V a duk cikin watannin sanyi. Wannan aikace-aikacen ya tabbatar da dacewar dandamalin ga wuraren nesa masu kula da amfani da wuta sosai inda amincin aiki yake da matuƙar muhimmanci.
Jerin Dubawa na Farko ga Masu Amfani na Farko
Fara da sabon aikin (clean project) a cikin Automation Builder. Daidaita samfurin CPU ɗin daidai yadda aka rubuta a kan kayan aikin. Saita adireshin IP idan kana amfani da Ethernet. Da fari ka sauke shiri babu komai (empty program) domin gwada sadarwa. RUN LED ɗin ya kamata ya yi walƙiya sannan ya tsaya ya zama ɗaya mai ɗorewa.
Na gaba, ƙara na'urar I/O ɗaya a lokaci guda. Sauke shirin (download) kuma ka gwada bayan kowace ƙara. Wannan yana ware kurakuran daidaitawa. Yawancin matsaloli suna fitowa ne daga kuskuren adireshin na'ura (module addressing). Tabbatar cewa ID na na'urar a cikin software ya dace da matsayin ramin (slot) a jikin na'urar. Rami 0 shi ne na'ura ta farko a gefen dama na CPU.
A ƙarshe, ka gwada duk wayoyin filin aiki ta amfani da force mode. Ka tilasta (force) kowane shigarwa daga na’urar filin sannan ka duba alamar a cikin software. Ka tilasta kowane fitowa sannan ka auna wuta a kan terminal. Wannan yana gano juyewar polarity da wayoyi da suka yanku kafin a fara samarwa.
Ajiyar Baya na Katin SD da Sabunta Firmware
Saka katin SD da aka tsara FAT32 (har zuwa 32GB) a cikin ramin CPU. Ka yi amfani da Automation Builder don kwafe aikin zuwa katin. CPU ɗin zai yi boot daga katin idan ciki (internal memory) ya zama babu komai. Wannan fasalin yana ba da damar maye gurbin na’urar da ta lalace cikin sauri. Ka ajiye CPU madadin tare da wannan katin SD ɗin a cikin kabad na masu kiyayewa.
Sabunta firmware na buƙatar Automation Builder update tool. Ka sauke fayil ɗin firmware daga shafin tallafin ABB. Ka haɗa ta Ethernet sannan ka gudanar da sabuntawar. Tsarin yana ɗaukar mintuna 3. Koyaushe ka ajiye (backup) aikin kafin sabuntawa. Sabunta firmware baya goge retentive variables, amma katse wuta yayin sabuntawa na lalata CPU. Ka yi sabuntawa ne kawai a lokacin lokacin tsayawa da aka tsara.
FAQ ga Injiniyoyin Kula da Tsari
Ta yaya zan saka idanu kan lokacin sikanni a ainihin lokaci ba tare da amfani da kayan aikin waje ba?
Ka yi amfani da system variable CYCLE_LOAD. Wannan integer 16-bit yana nuna lokacin sikanni na yanzu a microseconds. Ka haɗa shi zuwa holding register don nuni a HMI. Ana sabunta wannan variable a kowane sikanni. Don PM564, ƙimar da aka saba tana tsakanin 1200 zuwa 5000 gwargwadon girman shirin.
Shin AC500-eCo na iya sarrafa kirgawar bugun sigina 100 kHz?
Ee, amma ne kawai a kan takamaiman shigarwar high-speed counter. PM564 da PM565 suna da counters biyu na 100 kHz a ciki. Ka yi amfani da HS_COUNTER function block. Ka saita tacewar shigarwa zuwa ms 0.1. Don manyan mitoci (har zuwa 500 kHz), ka ƙara DC522 I/O module. Shigarwar dijital na al’ada ba za su iya wuce 1 kHz ba saboda iyakokin optocoupler.
Menene yawan loops PID mafi girma kafin aikin tsarin ya fara raguwa?
Gwaje-gwajen filin aiki sun nuna cewa loops PID 16 suna ƙara lokacin sikanni kusan ms 0.8. PM564 na iya sarrafa loops PID 24 cikin sauƙi tare da lokacin sikanni ƙasa da ms 8. Idan ya haura loops 32, ka yi amfani da PM567 CPU ko ka koma tsarin sarrafa rarrabbe (distributed control architecture). Kowane toshe PID yana ɗaukar ms 0.05 baya ga lissafin loop.
Shawarwari na Ƙarshe daga Ƙwarewar Filin Aiki
Koyaushe ka ƙara wa ƙarfin wutar lantarki kaso 30% sama da abin da ake buƙata. Ƙara fiyus na gida ga kowane rukuni na I/O. Ka saita ayyukan cyclic interrupt dabam don lissafin sauri. Ka yi daidaita PID da hannu ga tsarin da ke da jinkiri (dead time) ƙasa da ms 200. Ka saƙa (terminate) layin bas na RS-485 a ƙarfafinsa biyu. Waɗannan hanyoyin sun hana kusan kashi 90% na matsalolin filin aiki a cikin shigarwa da dama.
Dandalin AC500-eCo yana ba da sakamako na ƙwararru idan injiniyoyi suka bi ƙa’idojin ƙira yadda ya kamata. An san iyakokinsa kuma an rubuta su a fili. Yin aiki a cikin waɗannan iyakoki yana samar da na’urar sarrafa kansa mai dogaro da araha wadda ke aiki shekaru da yawa ba tare da buƙatar shiga tsakani ba.
