Honeywell HC900 Reference Guide

Function Blocks
LTCH Latch Function Block
Revision 11 HC900 Hybrid Control Designer Function Block Reference Guide 187
2/07
LTCH Latch Function Block
Description
The LTCH label stands for Latch.
This block is part of the
Logic and Fast Logic categories.
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.

Honeywell HC900 Specifications

General

Series	HC900
Redundancy	Optional
Programming Language	Function Block Diagram, Ladder Logic, Structured Text
Inputs	Analog, Digital
Outputs	Analog, Digital, Relay
Display	Optional
Control	PID, Advanced Control
Power Supply	24V DC or 100-240V AC
Storage Temperature	-40°C to 85°C
Humidity	5% to 95% non-condensing
Communication Protocols	Modbus, Ethernet