C_Pg
(proportional gain)
The proportional gain is the ratio between the
change in measured input and change in control
output. Too much proportional gain will result in
instability.
Example 1, if the proportional gain is set to
1.000
and the measured input changes by
100% of the span set in
C.SPN
then the output
will change by 100%.
Example 2, if the proportional gain is set to
2.000
and the measured input changes by 50%
of the range set in
C.SPN
then the output will
change by 100%.
Example 3, if the proportional gain is set to
2.000
and the measured input changes by 25% of the
range set in
C.SPN
then the output will change by 50%.
Setting a negative proportional gain will reverse the control output.
Effect of changing proportional gain and offset -
C.SPN
= 2.00,
A1.IG
= 0.000
C.Set C_PG
C_Po
Effect on analog output (4-20mA used in this example)
7.00
1.000
0.0
Reading of 5.00 or below - 20mA output.
Reading of 5.00 to 7.00 - mA output decreasing as reading approaches 7.00.
Reading 7.00 and higher - 4mA output.
7.00
1.000
100.0
Reading of 7.00 or below - 20mA output.
Reading of 7.00 to 9.00 - mA output decreasing as reading approaches 9.00.
Reading 9.00 and higher - 4mA output.
7.00
1.000
50.0
Reading of 6.00 or below - 20mA output.
Reading 6.00 to 8.00 - mA output decreasing as reading approaches 8.00
with 12mA output at 7.00.
Reading 8.00 or above - 4mA output.
7.00
0.500
50.0
0.
0
Reading of 5.00 or below - 20mA output.
Reading 5.00 to 9.00 - mA output decreasing as reading approaches 9.00
with 12mA output at 7.00.
Reading 9.00 or above - 4mA output.
7.00
-1.000
50.0
Reading of 6.00 or below - 4mA output.
Reading 6.00 to 8.00 - mA output increases as reading approaches 8.00 with
12mA output at 7.00.
Reading 8.00 or above - 20mA output.
Page 30 of 46
LD4LNMAN-1.0-1
PROPORTIONAL GAIN
TOO HIGH
PROPORTIONAL GAIN
TOO LOW
IDEAL
SETPOINT
PROCESS
TIME
PROCESS
PROCESS
SETPOINT
SETPOINT
20mA
20mA
12mA
12mA
4mA
4mA
Positive
value e.g.
C. PG
1.000
Negative
value e.g.
C. PG
-1.000
