Chapter - Continuous Control

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Chapter - Continuous Control
Examples
2
A Feedback Controller
3
Continuous Feedback - Logical Output
4
Ladder Logic Example
5
Block Diagram
6
An Example
7
Continuous Feedback and Output
8
Proportional Control Equations
9
Modeling Behavior with Differential Equations
10
Implementing the controller in ladder logic
11
Proportional Integral Differential (PID) Control
12
PID Control With Ladder Logic
13
PID CONTROL AND STATUS BITS
pid.CTLDINT pid.ENBOOL - the PID function is
enabled and running pid.PVTBOOL - pid.DOEBOOL
- 0d/dtPV 1d/dtError pid.SWMBOOL - 0
automatic, 1 manual pid.MOBOOL pid.PEBOOL -
0independent PID eqn 1dependent pid.NDFBOOL -
0no derivative smoothing 1derivative
smoothing pid.NOBCBOOL - 0no bias calculation,
1yes pid.NOZCBOOL - 0no zero crossing
calculation 1yes pid.INIBOOL - 0not
initialized 1initialized pid.SPORBOOL -
0setpoint not out of range, 1within pid.OLLBOOL
- 0above minimum CV limit 1outside pid.OLHBOO
L - 0below maximum CV limit 1inside pid.EWDBOO
L - 0error outside deadband 1error
inside pid.DVNABOOL - 0ok 1Error is below
lower limit pid.DVPABOOL - 0ok 1Error is
above upper limit pid.PVLABOOL - 0ok 1PV is
below lower limit pid.PVHABOOL - 0ok 1PV is
above upper limit
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pid.SPREAL setpoint pid.KPREAL - proportional
gain pid.KIREAL - integral gain pid.KDREAL -
derivative gain pid.BIASREAL - feed forward
bias pid.MAXSREAL - maximum scaling pid.MINSREAL
- minimum scaling pid.DBREAL -
deadband pid.SOREAL - set output
percentage pid.MAXOREAL - maximum output limit
percentage pid.MINOREAL - minimum output limit
percentage pid.UPDREAL - loop update time in
seconds pid.PVREAL - scaled PV
value pid.ERRREAL - scaled Error
value pid.OUTREAL - scaled output
value pid.PVHREAL - process variable high
alarm pid.PVLREAL - process variable low
alarm pid.DVPREAL - positive deviation
alarm pid.DVNREAL - negative deviation
alarm pid.PVDBREAL - process variable deadband
alarm pid.DVDBREAL - error alarm
deadband pid.MAXIREAL - maximum PV
value pid.MINIREAL - minimum PV
value pid.TIEREAL - tieback value for manual
control pid.MAXCVREAL - maximum CV
value pid.MINCVREAL - minimum CV
value pid.MINTIEREAL - maximum tieback
value pid.MAXTIEREAL - minimum tieback
value pid.DATAREAL17 - temporary and workspace
(e.g. integration sums)?
PID CONTROL REALS