Function Blocks
3/99 Function Block Reference Guide 93
2.33 LTCH Function Block
Description
The
LTCH
label stands for
Latch
.
This block is part of the
Logic
and
Fast Logic
categories. It looks like
this graphically on the Control Builder.
OR
Fast Logic
Function
Latches output
(OUT) ON when latch input (L) turns ON and maintain latched output until unlatch input
(U) turns ON. Note that latch input must be OFF for unlatch input
to work.
• If U = ON, then:
OUT = OFF.
• If L = ON, then:
OUT = ON.
•Else,
OUT = Previous State.
Input
L = Latch Command Digital signal.
U = Unlatch Command Digital signal.
Output
OUT = Digital signal
Block Properties
Double click on the function block to access the function block properties dialog box.
Block Order (Read Only)
You can change the assigned execution order number by selecting “Execution Order” in the “Configure”
menu and arrange the order to suit your control strategy.
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