ABB ControlMaster Series Manual page 21

Ratio controller
The ratio controller template configures the CM30 to regulate one process variable against another based on a specified ratio.
When using the ratio control template, the CM30's display shows the required ratio (setpoint) and the actual ratio achieved
(process variable).
In this example, a controlled amount of 'Flow B' is added to 'Flow A' at a ratio programmed into the CM30.
This template is available with or without an external ratio.
Controlled Flow (Flow B)
Wild Flow (Flow A)
Fig. 21: Ratio controller
Ratio station
The ratio station template configures the CM30 as an indicator and setpoint generator.
In this example, the CM30 is calculating and indicating the ratio of flow A and flow B. The operator is able to enter the desired
ratio on the CM30; the CM30 then retransmits the setting to the slave controller. In many applications, the slave controller is a
blind or remotely-located device.
This template is available with or without an external ratio.
FT
Controlled Flow
(Flow B)
Wild Flow
(Flow A)
Fig. 22: Ratio station
FT
I/P
FT
I/P
FT
ControlMaster CM30 | Universal process controller,
Input 1
Input 2
PV
O/P
RSP
PV
Slave
O/P
Controller
O/P RSP
DIN | DS/CM30–EN Rev. L
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