FC 24 - Adapt

This function allows the adaptation of a tunable parameter in the system (most tunable parameters may be modified during execution). It permits configuration of dynamic versus static loop gains in control schemes. All gains and time constants are tunable parameters. Therefore, using this function, you can set gains and time constants to fit current process operating states.

 

NOTE: Tunable alarm specifications in exception report function blocks are not adaptable (e.g., function code 30, S5 and S6).

 

The adapt function block output value has no significance. The adapted specification is modified only during execution, and the original parameter that is stored in nonvolatile random access memory (NVRAM) is not modified. Thus, the revised specification is not accessible via any of the operator interface devices unless the adapt input is read. Adapted block inputs are read by reading the output of the block preceding the block of interest.

 

Outputs:

Blk

Type

Description

N

N/A

No significance

 

 

Specifications:

Spec

Tune

Default

Type

Range

Description

S1

N

0

I

Note 1

Block address of input

S2

N

0

I

Note 1

Note 2

Address of block containing specification to be adapted

S3

N

0

I

0 - 64

Specification number of the specification to be adapted

 

NOTES:

1. Maximum values are: 9,998 for the BRC-100, IMMFP11/12, and 31,998 for the HAC.

2. The block address of the block to be adapted must be greater than the block address of the Adapt block.

 

The adapt function code has been enhanced to support cross type conversions for modules. The block internally converts the input value to the type of value required by the adapted block specification type. Table 24-1 shows the type of conversions performed. If the input type matches the output type, no conversion is performed. The specification value is changed to match the input value exactly when no type conversion is performed.

 

 

 

24.1 Applications

Figures 24-1, 24-2 and 24-3 illustrate some uses of the adapt function code.

Figures 24-1 and 24-2 show the input to an adapt block as the result of a function defined by function code 1. If the function varies with time, the adapted parameter also varies with time. The same is true for functions of pressure, temperature, tank level, etc. This arrangement makes variable control of tunable parameters possible, allowing compensation for gains inherent in a process.

 

In Figure 24-1, the high output limit S9 of a function code 19 block varies as a function of x as defined in a function code 1 block.

 

 

 

In Figure 24-2, an adapt block adapts with proportional constant S6 of a function code 19 block to the value received from a function code 1 block, allowing the modification of the proportional constant with changes in a specified parameter, x.

 

 

 

Figure 24-3 shows the use of an adapt block in conjunction with a function code 9 block to set a value to one of two

constants, depending on an external condition. The input to the adapt block can be a linear signal or a selected fixed signal.