【正文】 r c o mp ute r s a r e a p p e a ring o n the fa c to r y fl o o r, w o n39。 ll be the o nes le ft ho ldi ng a co mmuni c a ti o ns s tr uc ture tha t39。 t ye t ta l k to MA P. S i nc e i t39。 s Ind us tr i a l D iv isio n ,re po r ts th a t bec a us e o f the la c k o f a fir m d e fi ni tio n , O mro n39。 t a p p e a r i mme d i a te ly . S a ys La r r y K o ma r e k: R i ght no w , MA P i s s ti l l a mo v i ng ta r ge t fo r the ma nufa c tur e r s , a s p e c ifi cati on tha t i s no t fi na l . P r e s entl y, fo r e xa mp l e . p e o p l e a r e i ntr o d uc i ng p r o d uc ts to me e t the MA P 2 . 1 s ta nd a rd . Ye t2 . 1 b as ed p r o d uc ts w i ll b e o b s o l ete w he n the ne w s ta nd a r d fo r MA P 3 . 0 i s i ntr o d uc e d . B e c a us e o f thi s , ma ny P LC v e nd o r s a r e ho l d i ng o ff o n ful l MA P i mp l e me nta ti o ns . O mr o n, fo r e xa mp l e , ha s a n o ngo i ng MA P c o mp a ti bility p r o gr a m。 t j us ti fy D C S [ d i s tribute d c o ntr o l s ys te m] . Wi th the s ta r ti ng p r i c e ta gs o f c ho s e p r o d uc ts b e i ng r e l a tiv ely hi gh , a p r o gr a mma b l e c o ntr o l le r ma ke s s e ns e fo r s ma l l , l o w l o o p c o unt a p p l i catio n . T he s e c o nd i s w he r e yo u ha v e to i nte gr a te the l o o p c l o s e ly w i th the s e q ue nti a l l o gi c a l . B a tc h c o ntr o l lers a r e p r i me e xa mp l e , w he r e the s e q ue nc e a nd ma i ntai ni ng the pr oc ess va ria ble are i nter tw i ned so cl osel y tha t the be ne fi ts o f ha v i ng a p r o gr a mma b l e c o ntr o l le r to d o the s e q ue nti a l l o gi c a l o utw e ighs s o me o f the d i s a d va nta ge s o f no t ha v i ng a d i s tr ibute d c o ntr o l s ys te m. B i l l B a r ko v itz, p r e s id ent o f Tr i c o ne x, p r e d icts tha t a l l fut ur e c o ntr o l le rs tha t c o me o ut i n the p r o c e ss c o ntr o l s ys te m b us i ne s s w i l l e mb ra ce a lo t o f mor e P LC tec hnol o gy a nd a lo t mo re P LC func ti o nali ty tha n the y e v e r d i d b e fo r e . Communications and MAP C o mmuni c a ti o ns a r e v i ta l to a n i nd i v i d ual a uto ma ti o n c e l l a n d to b e a uto ma te d fa c to r y a s a w ho l e . We 39。 r e a p p r o pri ate. o ne , he s a ys , i s w he r e the s i ze o f the p r o c e s s c o ntr o l s ys te m tha t39。 i s tha t P LC s w i l l b e us e d i n the p r o c e ss i nd us tr y b ut no t ne c e s s a rily fo r p r o c e ss c o ntr o l. S e v e r al v e nd o r s o b v ious ly b e tti ng tha t the o p p o s ite w i l l ha p p e n ha v e i ntr o d uc e d P LC s o p ti mi ze d fo r p r o c e ss a p p l icatio n . R i c h Rya n, ma nge r, c o mme r c i a l ma r ke ti ng, A l l e n b rad ley P r o gr a mma b l e C o ntr o l s D i v. , c i te s P LC s 39。 s i nc r e a sing i nte r e st i n l a ngua ge s l i ke C a nd B A S IC . PLCs in process control T hus fa r, P LC s ha v e no t b e e n us e d e xte ns i v e ly fo r c o nti nuo us p r o c e ss c o ntrol . Will this c o nti nue ? T he feeli ng tha t I39。 P r o gr a mma b l e c o ntr o ls a r e b e i ng us e d fo r mo r e a nd mo r e s o p hi s ti cate d o p e r a tions , l a ngua ge s o t he r tha n l a d d e r l o gi c b e c o me mo r e p r a c tic al, e ffi c i ent, a nd p o w e rful . F o r e xa mp l e , i t39。 ge ne r a l ma na ge r, S i e me ns E ne r gy amp。 i n mo s t a me c ha nis m is pr ovi de d to a t l e a s t a l l o w s o me fl e xi b ili ty o f c ho o s i ng w hi c h p i ns a r e o utp uts a nd w hi c h a r e i np uts . T hi s ma y a p p l y to a l l o r s o me o f the p o r ts . S o me I/ O l i ne s a r e s ui ta b l e fo r d i r e ct i nte r fa c ing to , fo r e xa mp l e , fl uo r e s cent d i s p l ays , o r c a n p r o v i de s uffi c ie nt c ur r e nt to ma ke i nte r fa c ing o the r c o mp o ne nts s tr ai ghtfo rw ar d. S o me de vice s al low a n I/ O p or t to be co nfi gure d as a s ys te m b us to allow o ff c hi p me mo r y a nd I/O e xpa nsi o n. T his fa cili ty is po te nti all y us e ful a s a p r o d uc t r a nge d e v e l op s, s i nc e s uc c e s siv e e nha nc e me nts ma y b ec o me to o bi g for o n c hip me mo r y a nd i t is und esi rab le no t to b uil d o n the e xi s ti ng s o ftw a re b a s e . Serial input/output .S e r i al c o mmuni c a ti o n w i th te r mi na l d e v i c es i s c o mmo n me a ns o f p r o v id ing a l i nk us i ng a s ma l l numb e r o f l i ne s . T hi s s o r t o f c o mmuni c a ti o n c a n a l s o b e e xp l o i te d fo r i nte r fa c ing s p e c ia l func ti o n c hi p s o r l i nki ng s e v e r al mi c r o c o mp ute rs to ge the r . B o th the c o mmo n a s ync hr o no us s ync hr o no us c o mmuni c a ti o n s c he me s r e q ui re p r o to co ls tha t p r o v i de fr a mi ng ( s ta r t a nd s to p ) i nfo r ma ti o n . T hi s c a n b e i mp l e me nte d a s a ha r d w a re fa c i l ity o r U( S ) A RT ( Uni v e rsa l(sync hr o no us) a s ync hr o no us r e c e iv er/tr ans mi tter ) r e l iev ing the p r o c e sso r ( a nd the a p p l ica tio ns p ro gra mme r ) o f this low lev el, ti me co ns umi ng, de tail . t i s me rel y nec ess ar y to s e l e cte d a b a ud r ate a nd p o s s i bly o the r o p ti o ns ( numb e r o f s to p b i ts , p a r i ty, e tc . ) a nd l o a d ( o r r e a d fr o m) the s e r i al tr a ns mi tte r ( o r r e