Model 2000 Flow Computer Instruction Manual
2.0
GENERAL
DESCRIPTION
Model 2000 issue 21
Page No
46
Epsilon, if “SP Control” is “As PV Control”
e
SP
PV
e
SP
PV
e
e
e
P
I
D
P n
P n
=
−
=
−
=
−
−
∆
,
,
1
Epsilon, if “SP Control” is “Only I -action”:
n
1
n
D
initial
P
I
PV
PV
e
PV
SP
e
PV
SP
e
−
=
−
=
−
=
−
∆
When the PID controller is used in reverse mode:
e
e
e
e
e
e
P
P
I
I
D
D
= −
= −
= −
∆
∆
PID actions:
action
action
action
calc
D
d
gain
action
i
gain
I
1
n
action
n
calc
,
action
gain
P
action
D
I
P
Out
t
e
T
P
D
T
t
P
e
)
I
(
)
I
(
P
e
P
+
+
=
×
×
=
×
×
+
=
×
=
−
∆
∆
∆
Where
Pgain
: Proportional gain
Pband
: Proportional band
SP :
Set
point
SPinitial
: Initial set point ( = PV at start-up)
PV :
Process
value
PV,n
: Current Value of PV
PV,n-1
: Previous Value of PV.
eP,n
: Current Value of eP
eP,n-1
: Previous Value of eP
eP
: Epsilon for Proportional action
eI
: Epsilon for Integral action
∆
eD
: Epsilon for Derivative action
Paction
: Proportional action
Iaction,calc : Calculated Integral action
Iaction
: Finally used Integral action
Daction
: Derivative action
Ti
: Integration time
Td
: Derivation time
∆
t
: Last program cycle time
Outcalc
: Calculated Output value
When setting up PID Control Outputs the Analogue Outputs (See Analogue Outputs page) will need to be selected from the
Analogue Outputs variable tree and dragged across to the appropriate output as described on the analogue outputs page.
Summary of Contents for 2000
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