Tm hiu b nh v cc task ca cc b iu khin h Logix 5000
Tm hiu b nh v cc task ca cc b iu khin h Logix 5000
1) CPU v b nh
1.1.CPU
B iu khin ControlLogix 1756L61 c 2 CPU:
Logix CPU x l cc m chng trnh
Backplane CPU x l truyn thng vo-ra v gi-nhn d liu vi backplane. CPU ny hot ng c lp vi Logix CPU.
CompactLogix L32E ch c 1 CPU thc hin tt c cc cng vic. Tuy vy cc tc v lin quan n vo-ra v truyn thng c phn chia r rng ; nhng tc v ny m phng Backplane CPU
1.2.B nh
1.2.1 Phn loi b nh
B nh ca cc b iu khin Logix 5000 c chia lm 2 loi : user memory v nonvolatile memory
- User memory : B nh lu gi code v cc tham s ca projects.
B nh ny c c im khi mt ngun v acquy th d liu s b mt
- Nonvolatile memory: l ni lu tr ni dung ca user memory khi ta ct tr mt project
B nh ny cho php chng ta lu tr mt bn sao ca project ngay c khi b iu khin mt ngun.
i vi cc b iu khin trn phng th nghim, dung lng b nh ca chng nh sau:
- CompactLogix L32E :
+ User memory : 750KB
+ Nonvolatile memory : Industrial CompactFlash memory card 1784-CF64 ( 64M )
ControlLogix 1756-L61:
+ User memory : 2M
+ Nonvolatile memory: Industrial CompactFlash memory card 1784-CF64 ( 64M ) hoc 1784-CF128 ( 128M )
1.2.2 User memory:
a). Cu trc ca user memory:
B nh ca h Logix 5000 c chia lm 2 vng nh chnh :
1) Vng nh cha cc chng trnh ng dng (Program soure code )
2) Vng nh cha cc tham s ca h iu hnh v chng trnh ng dng:
Vng nh ny c chia thnh 6 vng nh hn:
a) Tag data : Min cha d liu cc base tag c ngi lp trnh nh ngha trong chng trnh.
b) RSlinx tags group list : Min cha d liu cc tag phc v giao tip gia b iu khin vi phn mm RSLogix 5000 qua phn mm RSlinx
c) I/O tag : Min cha d liu cc tag vo-ra. Cc tag ny c chng trnh t ng thit lp tng ng da trn cc khai bo v cc module vo-ra. Trng thi cc tag ny thay i tc th theo s thay i ca cc u vo ra, n khng phi l mt min b m vo ra.
d) I/O force tables : Bng trng thi ca cc module vo ra c ngi lp trnh p trng thi
e) Message buffers : Min cha cc b m phc v cho vic giao tip gia cc b iu khin vi nhau
f) Produced/Consumed tags : Min cha d liu cc tag c bit do ngi lp trnh nh ngha, phc v cho vic giao tip gia cc b iu khin vi nhau.
b). Qun l d liu :
Tag:
- Tag l i din cho mt khong nh lu tr d liu trong b nh ca b iu khin
- Cc b iu khin Logix 5000 xc nh cc d liu qua tn ca cc tag. Cc tag l mt c ch c bn cho php b nh qun l d liu
- Mt tag chim dung lng nh nht l 4bytes
- Tag c chia lm 4 loi :
+ Alias: tag ny i din cho mt tag khc. Alias tag c cng kiu d liu m n i din v mi thao tc thc hin vi alias tag s c chuyn n tag m n i din
+ Base : loi c bn
+ Produced : tag ny phc v cho vic chuyn d liu cho mt b iu khin khc
+ Consumed : tag phc v cho vic nhn d liu t b iu khin khc
Cc kiu d liu:
RSLogix5000 nh ngha sn mt s kiu d liu c bn. Khi ta nh ngha mt tag ta c th chn kiu d liu ph hp t cc kiu d liu c nh ngha. Ngoi ra, ta cn c th nh ngha cc kiu d liu mi (user-define data type) m ta cn s dng.
Di y l mt s kiu d liu thng dng:
2) Cc tc v (task) ca b iu khin
2.1.Cu trc mt Task
Mt Task cha nhiu Program, mi Program gm cc routine v cc bng qun l cc tag trong program .
Routine cha cc m lp trnh. Mi program c mt main rountine, l rountine c chy u tin trong program. Trong rountine c th gi routine khc trong cng mt program bng lnh JSR ( Jump to Sub-routine ). Cc routine trong cc program khc nhau th khng th gi. Ngoi ra cc routine cn c th gi cc add-on intructions
Add-on Intructions l mt tp hp lnh thng dng , do ngi lp trnh thit lp; c giao din giao tip vi chng trnh gi n. Mt Add-on Intructions c th gi cc Add-on Intructions khc nhng khng th gi cc routine. Cc Add-on Intructions c th gi lng nhau ln nht l 7. Add-on Intructions c s dng vi cc mc ch:
S dng li cc code qua cc project khc nhau
Cung cp mt giao din d s dng
Bo v cht xm
2.2.Phn loi Task
Mt b iu khin Logix5000 h tr 3 tc v c bn :
Tc v mc nh ( Continuous task )
Tc v tun hon ( Period task )
Tc v s kin ( Event task )
S lng cc task ty thuc tng b iu khin :
a). Tc v mc nh:
Mi b iu khin ch h tr duy nht mt tc v mc nh. thc hin tc v mc nh chn Main task/Main program/Main rountine trong project.
b). Tc v tun hon v tc v s kin :
xc nh th t thc hin cc tc v do ngi lp trnh thit lp, ta dng cc cp u tin (priority levels)
Ngoi cc task do ngi s dng thit lp, cn c cc task mc nh ca h thng. Cc task mc nh gm :
Montion planner: l mt period task, ngt tt c cc ngt khc
I/O processing: l mt period task, i vi cc b iu khin CompactLogix, FlexLogix, and DriveLogix n c th t u tin l 6
System overhead: gm cc task truyn thng v cc background task. System overhead ch c th ngt continuous task
Output processing: b iu khin update cc kt qu ra cc output module cui mi task
Module Input Data State Change : tc v s c gi khi c s thay i trng thi ca d liu u vo. Loi ngt ny c th c s dng khi vi s thay i on => off hoc off => on ca mt u vo s; hoc khi mt module vo s gi d liu ln b iu khin.
Consumed Tag : tc v c thc hin khi consumed tag (c chn lm iu kin kch thch) nhn
Axis Registration 1or 2 : tc v c thc hin khi u vo t n mt gi tr nh trc; s dng lnh Motion Arm Registration (MAR) xc nh iu kin kch thch
- Axis Watch: cng ging nh vi Axis Registration 1or 2 nhng s dng lnh Motion Arm Watch (MAW) xc nh iu kin kch thch.
Montion Group Execution : tc v c gi khi montion planner thc hin xong.
Event instruction: tc v c gi khi iu kin kch thch trong chng trnh lp trnh c tha mn
