SCD (sprvsry cntrl nd dt cqstn) s cntrl systm rchtctr cmprsng cmptrs, ntwrkd dt cmmnctns nd grphcl sr ntrfcs fr hgh-lvl sprvsn f mchns nd prcsss. t ls cvrs snsrs nd thr dvcs, sch s prgrmmbl lgc cntrllrs, whch ntrfc wth prcss plnt r mchnry.
Th prtr ntrfcs whch nbl mntrng nd th ssng f prcss cmmnds, sch s cntrllr stpnt chngs, r hndld thrgh th SCD cmptr systm. Th sbrdntd prtns, .g. th rl-tm cntrl lgc r cntrllr clcltns, r prfrmd by ntwrkd mdls cnnctd t th fld snsrs nd cttrs.
Th SCD cncpt ws dvlpd t b nvrsl mns f rmt-ccss t vrty f lcl cntrl mdls, whch cld b frm dffrnt mnfctrrs nd llwng ccss thrgh stndrd tmtn prtcls. n prctc, lrg SCD systms hv grwn t bcm smlr t dstrbtd cntrl systms n fnctn, whl sng mltpl mns f ntrfcng wth th plnt. Thy cn cntrl lrg-scl prcsss tht cn spn mltpl sts, nd wrk vr lrg dstncs. t s n f th mst cmmnly-sd typs f ndstrl cntrl systms.