160
Serial communications
ACH550-01 User's Manual
PID control feedback source selection
Code Description
Range
4010
SET POINT SEL
0…19
Defines the reference signal source for the PID controller.
• Parameter has no significance when the PID regulator is by-passed
(see 8121
REG
BYPASS
CTRL
).
8 =
COMM
– Fieldbus provides reference.
9 =
COMM
+
AI
1 – Defines a fieldbus and analogue input 1 (
AI
1)
combination as the reference source. See
Analogue input reference
correction
on page
160
.
10 =
COMM
*
AI
1 – Defines a fieldbus and analogue input 1 (
AI
1)
combination as the reference source. See
Analogue input reference
correction
on page
160
.
Analogue input reference correction
Parameter values 9, 10, and 14…17 use the formula in the following
table.
Where:
• C = Main reference value
(=
COMM
for values 9, 10 and =
AI
1 for values 14…17)
• B = Correcting reference
(=
AI
1 for values 9, 10 and =
AI
2 for values 14…17).
Example:
The figure
shows the reference
source curves for
value settings 9, 10,
and 14…17, where
:
• C = 25%.
• P 4012
SETPOINT
MIN
= 0.
• P 4013
SETPOINT
MAX
= 0.
• B varies along the
horizontal axis.
4014
FBK SEL
1…13
Defines the PID controller feedback (actual signal).
11 =
COMM
FBK
1 – Signal 0158
PID
COMM
VALUE
1 provides the
feedback signal.
12 =
COMM
FBK
2 – Signal 0159
PID
COMM
VALUE
2 provides the
feedback signal.
Value setting Calculation of the AI reference
C + B
C value + (B value - 50% of reference value)
C * B
C value · (B value / 50% of reference value)
C - B
(C value + 50% of reference value) - B value
C / B
(C value · 50% of reference value) / B value
120
100
80
60
40
20
0
0
100%
9, 14 (+)
16 (-)
10, 15 (*)
17 (/)
B
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