Re: [foxboro] is PID a parallel or series algorithm?
- From: "Joseph M. Riccardi" <Joe@xxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Wed, 11 Aug 2004 09:58:35 -0400
Folks,
Hopefully this helps; from a ControlSoft Inc. slide presentation ... =
(I
could not format some of the characters correctly, so it may be a little
difficult to follow; ie., Pe =3D Proportional sub error)
Three Different PID Equations (e =3D error)
- Parallel Pe + Ie + De
- Series P(e + Ie) + De
- Noninteracting (ISA) P(e + Ie + De)
Parallel format
G (t) =3D Kp e(t) + Ki I e(t)dt + Kd de(t)/dt
Gc (s) =3D KP + KI/s + KDs
P is Proportional Gain KP
I is Reset Rate Ki
D is Derivative Gain KD
Series (industrial) format
G (t)=3DKc ((1+Td/Ti) e(t)+1/Ti I e(t) + Td de(t)/dt
Gc (s) =3D Kc [1 + 1/Ti s] [(Td s+1)/(a Td s+1)]
a =3D 0 Gc (s) =3D Kc (1+1/Ti s)(1+Td s)
P is Proportional Gain Kc
I is Time Constant Ti
D is Time Constant Td
Non-interacting (ISA) format
G (t) =3D Kp (e(t) +1/Ti I e(t)dt +Td de(t)/dt)
Gc (s)=3D Kp (1 + 1/Ti s + 1/Td s)
P is Proportional Gain Kp
I is a Time Constant Ti
D is a Time Constant Td
Parallel comparison to Non-Interacting
KP Parallel =3D KP Non-Interacting
KI Parallel =3D KP NI / Ti NI
KD Parallel =3D KD NI * Td NI =20
Sure clears it up for me. :-))
Joseph M. Riccardi
DCS Services - Industrial Process Control
=20
North-Central Office (OH, PA, MI, IN, WV area)
South-East Office (FL, GA, AL, SC, NC area)
Joe@xxxxxxxxxxxxx
"To give real service you must add something that cannot be bought or
measured with money; and that is sincerity and integrity." - Donald A. =
Adams
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] =
On
Behalf Of Johnson, Alex (Foxboro)
Sent: Tuesday, August 10, 2004 12:34 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] is PID a parallel or series algorithm?
B0193JU - Control Block Algorithms
Could you expound on "serial" and "parallel" as the terms apply to PID
algorithms?
Regards,
=20
Alex Johnson
Invensys Systems, Inc.
10707 Haddington
Houston, TX 77043
713.722.2859 (voice)
713.722.2700 (operator)
713.932.0222 (fax)
ajohnson@xxxxxxxxxxx
For the latest information on ArchestrA, go to
http://www.invensys.com/Archestra.html.
=20
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] =
On
Behalf Of Miacca Marcelo
Sent: Tuesday, August 10, 2004 10:19 AM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] is PID a parallel or series algorithm?
Does anyone know where I can find the PID block algorithm in the Foxboro
documentation? Is it a parallel or series algorithm?
Thanks
Marcelo Miacca
=20
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