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3.10 Components of function blocks
The three components of a function block are:
Input parameter(s)
Function block parameter(s)
Output parameter(s).
Figure 3-7 shows the function block Alarm #1's components.
Func ti on bloc k p aram ete r
Fu nc ti on bloc k p aramete r
In put param ete r
In put paramete r
In put paramete r
Fu nc ti on bloc k p aramete r
Func ti on bloc k p aram ete r
Input parameter
A function block's input parameter can be configured to be OFF, a number, or it can receive its data from
outside the block from another block's output codes.
Table 3-4. That is, an input parameter is any menu item that can be programmed as (connected to) one
of these output codes. These output codes are grouped under the menu choice PARM. When you are
programming a function block and one of your choices is PARM, you know you are programming an
input parameter. See Figure 3-7.
For example, suppose you are programming an alarm function block. One of the alarm's menu items is
INPUT, which specifies which point will be monitored for an alarm condition. One of the choices for the
INPUT is PARM, which lets you connect the INPUT to one of the output codes in Table 3-4. Therefore,
the INPUT is an input parameter because it receives its data from another function block.
Some function blocks can have multiple input parameters. For example, an Alarm function block has an
INPUT and a SETPOINT, both of which can be connected to other function blocks.
Discrete Input function blocks have no input parameters; that is, they have no inputs that can be
connected to another block's output codes.
Al a rm 1 F u nc ti on Bl o c k
ALARM ACTION ( Select H igh, L ow, Dev , LRat e, H Ra te )
IN D ECI MAL POS ( Selec t input d ec ima l pos it ion)
IN PUT (Selec t O FF , Nu mb er, o r PARM)
SETPOI N T (Select OF F, Nu mb er or PARM)
CO MPARE P OI NT (Selec t O FF , N umber, or P AR M)
HY STER ESIS ( Select OFF or Nu mb er)
DE LAY TIME (Select O FF o r N umber)
Figure 3-7 Alarm 1 Function Block Components
Video Recorder – User Manual
Programming and Operating Concepts
Outp ut param et ers
AL 1 O S (Alarm s ta te )
AL 1 S 2 (C omp are point o f
De vi ati on alarm o nly )
AL 1 P V (Value of a larm' s IN PUT)
These output codes are shown in
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