Qee lub sij hawm thaum programming machining, koj tuaj yeem ntsib qhov xwm txheej uas ib pawg ntawm cov haujlwm ntu tshwm sim ntau zaus hauv ib qho kev pab cuam, lossis siv ntau yam haujlwm. Peb tuaj yeem rho tawm cov pab pawg ntawm cov haujlwm ntu no, npe rau lawv, thiab khaws cia nyias; pawg ntawm cov kev pab cuam ntu no hu ua subroutine. Lub subroutine yog ib qho kev pabcuam machining ntu uas tuaj yeem hu tau los ntawm cov lus qhia siv lub tshuab tsim nyog, thiab nws feem ntau muaj lub ntsiab lus ywj pheej thaum lub sijhawm machining. Qhov kev pab cuam machining uas muaj cov lus qhia hu rau thawj -theem subroutine hu ua lub ntsiab program. Cov lus qhia hu rau lub subroutine kuj yog ib qho kev pab cuam, uas feem ntau muaj cov kev qhia hu rau subroutine, lub npe subroutine, thiab tus xov tooj hu. Cov cai tshwj xeeb thiab cov qauv sib txawv nyob ntawm qhov system. Piv txwv li, rau tib txoj kev qhia "hu subroutine tooj 55 ib zaug," FANUC system siv "M98 P55.", thaum American AB system siv "P55x."
Subroutines tuaj yeem ua zes, uas yog, ib qib hauv lwm qhov. Kev sib raug zoo ntawm qib siab thiab qis dua yog tib yam li kev sib raug zoo ntawm cov haujlwm tseem ceeb thiab thawj - theem subroutine. Qhov siab tshaj plaws ntawm qib nested yog txiav txim siab los ntawm cov txheej txheem CNC tshwj xeeb. Daim ntawv thiab muaj pes tsawg leeg ntawm ib tug subroutine feem ntau zoo ib yam li cov ntawm cov kev pab cuam tseem ceeb: thawj kab yog tus lej subroutine (lub npe), thiab kab kawg yog "subroutine kawg" kev qhia, nrog lub subroutine lub cev nyob nruab nrab ntawm. Txawm li cas los xij, qhov kev qhia tseem ceeb kawg yuav xaus qhov kev pab cuam tseem ceeb thiab rov pib dua CNC system; nws cov lus qhia yog tus qauv, nrog rau txhua qhov system siv M02 lossis M30. Cov lus qhia kawg ntawm subroutine, ntawm qhov tod tes, txiav tawm lub subroutine thiab rov qab mus rau qhov haujlwm tseem ceeb lossis cov txheej txheem dhau los. Nws cov lus qhia sib txawv ntawm cov kab ke; Piv txwv li, FANUC systems siv M99, Siemens systems siv M17, thiab AB (American A/B) systems siv M02.