Bronkhorst®
Instruction Manual ES-FLOW™
9.17.116B
40
Default configuration
Network configuration is done ex factory, as indicated on the instrument label or in the technical specifications. The table
below shows the supported configurations for the different interface protocols (default settings are printed in boldface):
Protocol
FLOW-BUS
(RS232)
FLOW-BUS
(RS485)
Modbus
(RTU/ASCII)
PROFIBUS DP
DeviceNet™
Bus address
3
3
…125
1
…247
0…
126
0…
63
Baud rate
9600
19200
38400
57600
115200
230400
460800
187500
400000
9600
19200
38400
56000
57600
115200
128000
256000
(autodetect)
9600
19200
45450
93750
187500
500000
1500000
3000000
6000000
12000000
125000
250000
500000
Parity
0
0
0, 1,
2
2
0
3.4.8
Controller
The picture below shows a basic diagram of the PID controller algorithm (proportional, integral, derivative) used in a digital
instrument.
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.
