Rockwell Automation SP600 User Manual Version 3.0 User Manual
Page 133
Parameter Descriptions
11-31
Proportional control (P) adjusts the output based on the size of the
error (larger error = proportionally larger correction).
Integral control (I) adjusts the output based on the duration of the
error. The integral control by itself is a ramp output correction. This
type of control gives a smoothing effect to the output and will
continue to integrate until zero error is achieved.
By itself, integral control is slower than many applications require,
and, therefore, is combined with proportional control (PI).
The purpose of the PI regulator is to regulate a process variable
such as position, pressure, temperature, or flow rate, by controlling
speed.
There are two ways the PI regulator can be configured to operate
(see parameter 124):
• Process trim, which takes the output of the PI regulator and sums
it with a master speed reference to control the process.
• Process control, which takes the output of the PI regulator as the
speed command. No master speed reference exists, and the PI
output directly controls the drive output.
Note that Speed Mode (80) must be set to Process PI (2).
Bit 0 - PI Enable
• Enables/disables the operation of the PI loop.
Bit 1 - PI Hold
• Enabled = The integrator for the outer control loop is held at
the current level; that is, it will not increase.
• Disabled = The integrator for the outer PI control loop is
allowed to increase.
Bit 2 - PI Reset
• Enabled = The integrator for the outer PI control loop is reset
to zero.
• Disabled = The integrator for the outer PI control loop
integrates normally.
Figure 11.11 – PI Control (125)
0
0
x
0
x
x
x
x
x
x
x
x
x
x
x
x
10
0
1
2
3
4
5
6
7
8
9
11
12
13
14
15
1 =Enabled
0 =Disabled
x =Reserved
Bit #
Factory Default Bit Values
PI Enable
PI Hold
PI Reset
Nibble 1
Nibble 2
Nibble 3
Nibble 4