Instruction manual

Digital Latches

154

890USE18300 September 2003

Operational

Input

The operational input is a pulse train of Boolean 1s and 0s that will be latched at any

time by the rising edge of the latch trigger. It may be produced by:

a digital input or output from a module on the island

a digital output from the virtual module

an input data bit from a channel on the action module

if the latch is the second block in a nested reflex action (See Nesting Two Reflex

Blocks, p. 36), the latch trigger input may be the output from the first reflex block

The following timing diagram shows how the value of the trigger effects the output

from the block:

At the beginning of the timing sequence, the operational input is high when the

trigger rises from 0 to 1. The standard output is latched at 1(the inverted output is

latched at 0).

The output value remains latched until the latch trigger rises from 0 to 1 a second

time. At that moment, the operational input is low. The standard output is latched at

0 (the inverted output is latched at 1).

When the latch trigger rises from 0 to 1 the third time, the operational input is high.

The standard output is latched again at 1 (the inverted output is latched at 0).

operational input

latch_trigger

output

inverted