Bronkhorst®
Instruction Manual mini CORI-FLOW ML120
9.17.097G
46
The output value of any instrument connected to FLOW-BUS is automatically available to all other instruments (without
extra wiring). A FLOW-BUS system can have multiple masters and slaves. A slave instrument can also be a master to other
instruments.
To setup a master/slave relationship between instruments, first determine which instrument should be the master and
which should be the slave, then set
Control Mode
of the slave instrument to ‘FLOW-BUS Slave’ (value 2) or ‘FLOW-BUS Analog
Slave’ (value 13), depending on how the setpoint should be calculated (see parameter
).
The slave instrument polls the output value of its master periodically and multiplies it by the slave factor, thus setting its
own flow to a percentage of the master's.
Setpoints from master instruments can be received via FLOW-BUS only.
To avoid damage to the instruments an/or the system(s) they are connected to, be sure to avoid circular references between
devices on the same fieldbus. The FLOW-BUS system does not have a protection mechanism.
Master Node
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Unsigned char
RW
1…128
158
33/14
n/a
Set the master node for the instrument
Note that this parameter only is effective in a FLOW-BUS system via RS485.
Slave Factor
Type
Access
Range
FlowDDE
FLOW-BUS
Modbus
Float
RW
0…500
139
33/1
0xA108…0xA109/41225…41226
The controller output from the master instrument is multiplied by
Slave Factor
/100% to get the slave instrument setpoint.
In systems other than FLOW-BUS via RS485,
Slave Factor
is effective only if
Control Mode
is set to 'Analog slave', and the
analog output signal of the master instrument is redirected to the input of the slave instrument.
Example:
·
master output = 80%
·
Slave Factor
= 50
slave instrument setpoint = 80% x 50%/100% = 40%
4.10
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.