Bronkhorst®
Instruction Manual mini CORI-FLOW ML120
9.17.097G
47
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 9.17.030). This manual
can be downloaded from
http://www.bronkhorst.com/en/downloads.
Because controlling characteristics are optimized during manufacture, Bronkhorst strongly advises not to
change these parameters. If changing controller settings is absolutely necessary, it should be performed by or
under supervision of trained service personnel only.
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 set.
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
0…1E+10
167
114/21
0xF2A8…0xF2A9/62121…62122
PID controller proportional action, multiplication factor.
PID-Ti
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Float
RW
0…1E+10
168
114/22
0xF2B0…0xF2B1/62129…62130
PID controller integral action in seconds.
PID-Td
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Float
RW
0…1E+10
169
114/23
0xF2B8…0xF2B9/62137…62138
PID controller derivative action in seconds. The default value is 0.0.
Open From Zero Response
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Unsigned char
RW
0…255
165
114/18
0x0E52/3667
Response factor, applied to proportional action when opening the valve from 0%.
·
Default value: 128 (no correction)
·
Other values adjust the controller gain (correction signal) as follows: Controller gain =
Controller Speed
*
PID-Kp
*
1.05
(response factor - 128)