Bronkhorst®
Instruction Manual mini CORI-FLOW™ M1x
9.17.050O
39
Density
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Float
RW
B
0…3.4E+38
170
33/21
0xA1A8…0xA1A9/41385…41386
Density of the current fluid in kg/m
3
4.6
Controller
The picture below shows a basic diagram of the PID controller algorithm (proportional, integral, derivative) used by digital
Bronkhorst® instruments.
The controller speed controls the overall performance of the controller algorithm. Basically, to adjust the controller
response, only the controller speed needs to be changed.
The algorithm is based upon the difference between the setpoint and the measured value (called the error value). The
correction signal to eliminate the error is assembled from 3 basic components:
·
The P-action (proportional) multiplies the error value by a constant factor, to adjust the measure towards the (new)
setpoint.
·
The I-action (integral) amplifies the correction signal with a factor depending on the integral of the error value over time.
·
The D-action (derivative) reduces the strength of the P-action, to prevent overshoot when the (new) setpoint is reached.
The proportional action is enhanced by one of three additional response factors, depending on the control cycle stage:
·
Open from zero: the setpoint is larger than zero and the measured value is below 2% of the full scale range.
·
Normal step: the measured value differs more than 2% from the setpoint, typically after changing the setpoint (step).
·
Stable situation: the measured value differs less than 2% from the setpoint.
For more information about controlling characteristics, consult the
FlowPlot manual
(document no. 9.17.030).
The control characteristics are optimized during production. These parameters should only be changed if absolutely
necessary, and only by or under the supervision of trained service personnel.
Controller Speed
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Float
RW
0.2…5
254
114/30
0xF2F0…0xF2F1/62193…62194
This parameter sets the overall controller speed factor for the selected fluid.
Controller speed
is set ex factory between value
'0.5' (slow) and '2' (fast). The default value is '1'.
PID-Kp
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Float
RW
B
0…1E+10
167
114/21
0xF2A8…0xF2A9/62121…62122
PID controller proportional action, multiplication factor.
