ABB ACS580 Firmware Manual page 104

100 Program features
In process PID control, a process reference (setpoint) is connected to the drive
instead of a speed reference. An actual value (process feedback) is also brought
back to the drive. The process PID control adjusts the drive speed in order to keep
the measured process quantity (actual value) at the desired level (setpoint). This
means that user does not need to set a frequency/speed/torque reference to the drive
but the drive adjust its operation according to the process PID.
The simplified block diagram below illustrates the process PID control. For more
detailed block diagrams, see pages
Setpoint
AI1
Process
AI2
actual
• • • values
FBA
The drive contains two complete sets of process PID controller settings that can be
alternated whenever necessary; see parameter
Note: Process PID control is only available in external control location EXT2; see
section Local control vs. external control
452 and 453.
Process
Filter
PID
40.57 PID set1/set2
(page 85).
Limitation
Speed, torque or
frequency
reference chain
selection.