Table of Contents
Advertisement
2.6 Single Loop with Feedforward (Templates 9 and 10)
These templates provide three-term PID control with feedforward. The disturbance variable is
weighted by the feedforward gain (FFGn) and the feedforward bias (FFbS) values and added to the
controller output value.
Local Set Point
LSPt
Remote Set Point input
•1
RSPt x rAtO + bIAS
I/P3
PV input
I/P1
Feedforward Disturbance Variable
I/P2
•1 Template 10 Only
Control
Set Point
•1
Process
Variable
OP1
Control
Set Point
Process
Variable
FF
•1 With the Ramping Set Point function enabled (see Section 3.3, Set Points/ Ramp Rate), the
bargraph shows the actual (ramping) set point value and the digital display shows the target set point
value.
L
DV x FFGn + FFbS
Fig. 2.5 Single Loop Controller with Feedforward
450. 2
500. 0
•1
70
450. 2
500. 0
50
L R
Manual Output
CSPt
PID
MPV
Control Loop
FFGN = 0
Process Variable
Control Set Point
['SPLO' to 'SPHI' – see Section 4.5]
Adjustable in Local control only.
Control Output
[0 to 100%]
Adjustable in Manual control only.
Feedforward
Note. To disable feedforward action (e.g.
during system tuning), set the Feedforward Gain
parameter to
0FF
Tune.
[0 to 100%]
Feedforward disturbance variable signal.
Continued...
2 OPERATOR LEVEL...
∑
PID O/P +
(DV x FFGn + FFbS)
– see Section 3.2, Tune/Level 2 –
OP1
19
Advertisement
Table of Contents
