Ratio

Description

The Ratio function is used to carry out the report process control; in other words, to assign a size to the value of the external input (control value).

The Ratio function calculates the loop controller setpoint according to the control value, by applying the following formula:

SP = RATIO x (SP Remote 1) + RATIO_BIAS

where:

SP Remote 1 = control value.

It is possible to define maximum and minimum limitations on the ratio reports.

NOTE: The size connected to the SP Remote 1 input is an external process value rather than a setpoint.

Functional diagram of the Ratio function:

Parameters

Input Parameter:

Parameter	Symbol	Type	Thresholds	Default Value	R/W
Setpoint input	/	%MFi	-3.4E38 / 3.4E38	/	R

Internal parameters:

Parameter	Symbol	Type	Thresholds	Default Value	R/W
Ratio value	RATIO	REAL	-3.4E38 / 3.4E38	1.0	R/W
Min ratio value	RATIO_MIN	REAL	-3.4E38 / 3.4E38	0.0	R/W
Max ratio value	RATIO_MAX	REAL	-3.4E38 / 3.4E38	100.0	R/W
Ratio bias	RATIO_BIAS	REAL	-3.4E38 / 3.4E38	0.0	R/W

Output parameters:

Parameter	Symbol	Type	Thresholds	Default Value	R/W
Setpoint value	SP	REAL	-3.4E38 / 3.4E38	/	R
Scaling Error	RATIO_WARN	EBOOL	/	/	R

Execution Monitoring

Monitoring the parameters is integrated into the error management of the setpoint branch.