Emerson FB2200 Flow Computer Control

Control

The FB2200 optionally supports control functions

including PID control, basic programming through

action blocks, effects, and math blocks.

PID Control – The FB2200 supports up to three

Proportional, Integral, and Derivative (PID) control

loops. Each PID instance supports a primary and an

override loop. Each loop has its own user-defined

input, output, and override capability.

Typically, a PID control maintains a process variable at

set point. If you configure a PID override control, the

primary loop is normally in control of the control

device but the override loop can take over control of

the process if required. A typical example would be

primary flow control with a pressure override.

Action Blocks – The FB2200 supports up to 30 action

blocks. Action blocks are used in conjunction with

effect blocks to monitor a configured condition and to

perform an action (effect) when the logic is “true.” An

action block consists of a user defined Boolean logic

statement with two variables. These variables can

either be live parameter values or constants.

Multiple action blocks can be chained together to

create more complex logic. Each action block includes

multiple bypasses, which can temporarily halt the

action to be taken for maintenance and safety.

Effects – The FB2200 supports up to ten effects. Effects

cause an action to occur when the result of one or

more action blocks is active (“true”). Multiple action

blocks can cause the same effect, such as shutting a

valve or enabling an alert beacon.

You configure an effect by defining an output

parameter and the values to write to that parameter

when the effect is either active or inactive. You can also

configure an active effect to be self-clearing or to

require a manual reset.

Math Blocks – The FB2200 supports up to ten math

blocks. Math blocks perform mathematical equations

using user-defined variables as inputs. Each math

block consists of up to four user-defined variables,

three mathematical calculations, and the results of

each calculation.

The result of the math block equation can be assigned

to a user data point, to drive an output point, to a

calculated value or to any other data base parameter.

Mathematical calculations also support standard math

functions (POW, EXP, LOG, SQRT, etc.), constants, and

operators.

FBxConnect checks each calculation string for the

correct syntax and uses double precision floating point

math throughout the calculation.

User Data Points – User data points are configurable

storage areas in the data base. These user data points

can store the constants / variables that are inputs to

the math blocks in addition to the calculated results of

math blocks. They can also be used to represent

interim calculation values or values of additional inputs

or outputs etc. There are eight user data instances,

each with a tag and description, 30 integers (split

between byte, short and long), 20 single floating

points, and 10 double floating points, providing

storage for up to 480 variables.