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Figure B-4. FST Function Structure

The FST program provides the STEP numbers (0-299) for each FST. You complete the other fields in the structure to build a function.

NOTE:Do not skip any STEPs. The FST program treats a blank STEP as the END of a program and will not compile correctly.

B.4.1 Label

The LABEL field allows you to uniquely identify a function and consists of up to six alphanumeric characters in any combination. A LABEL identifies the action being performed by the function. For example: The LABEL “PUMPON” describes a function that activates a pump.

LABELs enable referencing of one function to another, called branching. For example, after

completion of a given program STEP, a GO command that has a LABEL provided in ARGUMENT1 directs the program to advance to the branch identified by the LABEL and to perform the functions defined there.

STEP LABEL CMD ARGUMENT 1 ARGUMENT 2

0 PUMPON GO PMPOFF

1 PMPOFF

In the example above, the program is instructed to GO to the LABEL PMPOFF as established by ARGUMENT 1 in STEP 0. STEP 0 jumps to STEP 1, where the LABEL PMPOFF is located.

B.4.2 Command – CMD

The FST command (CMD) field specifies the action to be taken by a function and is identified by a one, two, or three-character mnemonic. Table B-4 shows the function commands and provides a brief description of how they operate on the RR, CF, and Argument values. Section B.11, Command Library, on page B-18 describes the command set in detail.

STEP LABEL CMD ARGUMENT 1 ARGUMENT 2

0 GO

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B.4.3 Arguments

Arguments can be numerical constants, ASCII characters, or data read from or written to applications you develop or embed in the firmware (software).

Table B-2 on page B-7 lists mnemonics and their descriptions for the pre-defined point types used with FST programs. The @ symbol in each mnemonic indicates the point type has been pre-defined in the FST software and must be included in any reference to point types.

STEP LABEL CMD ARGUMENT 1 ARGUMENT 2

0 @IOA1,Tag Name, EU 100

After pressing F9 to select the ARGUMENT Point Type and Point Number (@IOA1,Tag Name), press F10 to select the corresponding Parameter (EU) that you desire to monitor, read, store, or alter (write). In the previous example, @IOA1 is the Point Type, Point Number, and Tag Name, and EU is the Parameter.

Table B-2. Pre-defined Point Type Mnemonics

Mnemonic Description

@AGA American Gas Association Flow Calculation

@CLK Real-time Clock

@COM Communication Ports

@FLG ROC Flags

@FLW Meter Flow (FloBoss 103 and FloBoss 500-Series) @FST Function Sequence Table Registers

@IO Physical I/O

@MVS Multi-variable Sensor (FloBoss 407 only) @PID Proportional/Integral/Derivative Control

@PWR Power Control Tag (FloBoss 103 and FloBoss 500-Series)

@RUN Meter Run

@SFP Softpoints

@SMP Meter Calibration and Sampler (FloBoss 103 and FloBoss 500-Series)

@SYS System Parameters

@TNK Tank Management (ROC300-Series with ROCPAC only)

@XRN Extra Meter Run

In the following example, the argument @IOB9, TankLevel, EU, used with the VAL command, returns to the Results Register (RR) the real-time Value of a Tank Level in scaled engineering units (EU). The parts of this argument are as follows:

The argument structure begins with the mnemonic @IO, followed by the slot Point Number location of the physical input within the ROC or FloBoss. The Point Number indicates the location of the point (such as rack and module number) in the ROC or FloBoss. The Point Number is automatically assigned by the ROC and cannot be edited. Each input or output has a unique Point Number to identify the I/O.

The Point Tag for the physical input comes next. Tank Level is the user-assigned Tag for Point Number B9. The Point Tag is assigned in the I/O parameter screens of ROCLINK software.

B-8 FST Editor Rev 05/03

Last comes the desired Parameter of the Point Type. In this example, EU is the Parameter. This Parameter specifies the current process value for input B9 scaled in engineering units.

User-defined Tags are created by entering and configuring points in ROCLINK software I/O point displays. For example: “@IOB9, Tank Level, EU” is the Discrete Input located at Point Number B9 with a Tag name of Tank Level.

NOTE: The Tag must be unique for the ROC or FloBoss to use it for the shorthand notation feature. If there are duplicate Tag names, the FST Editor selects the first one in the list.

B.4.4 Function Examples

In the example shown in Figure B-5, the @IO point type is combined with a LABEL (CKHIAL) and CMD (VAL) to create a function. The function writes the current process value (VAL) of the Tank Level, inEUs, to the Results Register, RR.

STEP 1 compares the RR value from STEP 0 with the HIAL (high alarm) value configured for the Tank Level point. If the RR value is greater than or equal to (>=) HIAL, the program branches to the

PUMPON LABEL. The LABEL CKHIAL (check high alarm)allows another function to branch to this function. For example, the ARGUMENT2 PUMPON indicates that the FST branches to the Step labeled PUMPON.