Introduction to Programming
Chapter 4
48
When the Mode Select Switch is changed from the RUN or RUN/PROG
position, the last true Output Latch or Output Unlatch instruction continues
to control the addressed memory bit, but disables the output device. When
the Mode Select Switch is turned back to RUN or RUN/PROG position, a
latched output device will be energized.
The Output Latch and Unlatch instructions, when entered, are
automatically set off. They can be initially preset on by entering the
number 1 immediately after the bit address. The on or off condition will be
displayed below the instructions when the processor is in the prog mode
(Figure 4.10). When the mode select switch is turned to the RUN or
RUN/PROG position, the addressed memory bit and output device, if
latched on, will immediately be energized, regardless of rung conditions.
WARNING: Do not preset a bit on controlled by Latch/Unlatch
instructions if it controls potentially hazardous machine motion.
If the bit is preset on by the Latch/Unlatch instructions, the
output device controlled by that bit is energized immediately
when the mode select switch is turned to the RUN or
RUN/PROG position. Hazardous machine operation could
damage equipment and/or personal injury could result.
Both Latch and Unlatch instructions can be programmed unconditionally.
This programming technique is generally used with storage bits and should
not be used to control output devices.
Figure 4.10
Latch
and Unlatch Indication
||
04
(
L )
OFF 00
112 014
||
05
( U )
OFF 00
112 014
Indicates
On or Of
f
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
Need help?
General
