Function block display
Function block displays are transparent to enable underlying wires or blocks to show through a block positioned on top of them. Outlines of the block, parameter names, mnemonics, tag names and descriptions, and parameter values all appear in blue, by default. Text that the user enters appears in black, by default. If desired, modify these colors.
TIP:
When a connection in a Function Block diagram appears as a diagonal line, rearrange the elements to create more space in the diagram. When the connection fits in the diagram, the line changes to an orthogonal line.
Some function block instructions contain one or more special arrays. In these cases, the name of the array appears after the visible parameters. The tag assigned to the array displays next to the special array name. If no tag is assigned, the array name still appears.
Functions in the
Function Block Diagram Editor
are similar to instructions, but do not require backing tags, require less memory than instructions, sometimes execute more quickly, and use less space in a function block diagram.
TIP:
Function Block functions are available only on
CompactLogix
5380, CompactLogix
5480, ControlLogix
5580, Compact GuardLogix
5380, and GuardLogix
5580 controllersThis picture illustrates how a typical function appears in a function block diagram. The two nodes on the left side of the function are inputs, and the single node on the right side is an output. Functions are labeled with a symbol rather than with text.
TIP:
To hide or display the value of output pins on functions or the input pins on function blocks, select
Tools > Options
to open the Workstation Options
dialog box. Select FBD Display and select or clear Show values of FBD Function output pins
and Show values of input pins
. Values are displayed by default.This picture illustrates how a typical function block instruction appears in a function block diagram.
This table provides examples from the instruction illustration with descriptions of the elements in the function block display:
Item | Element | Example | Description |
1 | Block Tag Description | ALM tag description | The description entered for this tag. |
2 | Instruction Mnemonic | ALM | The abbreviation for the name of the instruction, also referred to as a mnemonic, that is associated with this block. |
3 | Block Properties Button | ... | Click this button to access the Function Block Properties dialog box.It is also acceptable to press Alt + Enter to access the Function Block Properties dialog box. |
4 | Type Description | Alarm | The description associated with this block type. The data type for the tag is the structure type associated with the block type. If deleting this tag from the Tag Editor , the Function Block editor considers this tag an unknown type, and a blue X appears next to the Type name indicating that the block is not verified. |
5 | Block Tag Name | ALM_01 | The name of the tag associated with this block. When creating the function block, the Function Block editor assigns a default tag name. To edit this name, double-click the name and choose another tag from the Tag Browser, or rename the tag on the Tag tab of the Function Block Properties dialog box.
TIP:
|
6 | Input Parameter | In | Input parameters for the function block appear on the left side of the block. |
7 | Output Parameter | HHAlarm | Output parameters for the function block appear on the right side of the block. |
8 | Data References | In a function block routine, external tags or system values can bring in data, external tags or system values can send out data, and signals can be transmitted across routines without wiring. To do this, use:
|
Provide Feedback