Rockwell Automation 1772-LP3 PLC - 2/30 Programmable Controller Programming and Operations Manual - Manual (Page 150)

Output Override and I/O Update Instructions
Chapter 7
7Ć8
The Immediate I/O instructions are programmed with the processor in
the program mode. When entered from the industrial terminal, they will
be displayed as intensified and blinking with the reverse-video cursor
positioned on the first digit of the default word address. The number of
digits in the default address can range from 4 to 5 depending on data table
size. Refer to Table 7.A for a summarized description of these instructions.
The 4- or 5-digit default word address with leading zeros will
automatically appear above the instruction provided the data table has been
expanded accordingly. To enter a 4- or 5-digit address when 4 or 5 digits
are displayed, the programmer must enter leading zeros before entering the
word address.
Table 7.A
Output Override and I/O Update Instructions
NOTE: The MCR and ZCL boundary instructions have no word address.
The word addresses, XXX, of the IMMEDIATE INPUT and OUTPUT instructions are limited to the Input and Output Image Tables respectively.
Displayed word addresses will be 3, 4, or 5 digits long, depending on Data Table size. When entering the word address, use a leading zero if
necessary.
Keytop Symbol Instruction Name 1770ĆT3 Display Description
-(MCR)- MASTER CONTROL
RESET
-(MCR)- Two MCR instructions are required to control a group of
outputs. The first MCR instruction is programmed with
input conditions to begin the zone. The second MCR
instruction is programmed unconditionally to end the zone.
When the first MCR rung is FALSE, all outputs within the
zone, except those forced ON or latched ON, will be
deĆenergized.
Do not overlap MCR zones, or nest with ZCL zones. Do
not JUMP to LABEL in MCR zones.
-(ZCL)- ZONE CONTROL
LAST STATE
-(ZCL)- Two ZCL instructions are required to control a group of
outputs. The first ZCL instruction is programmed with input
conditions to begin the zone. The second ZCL instruction
is programmed unconditionally to end the zone.
When the first ZCL rung is FALSE, outputs in the zone will
remain in their last state.
Do not overlap ZCL zones, or nest with MCR zones. Do
not JUMP to LABEL in ZCL zones.
-[ I ]- IMMEDIATE INPUT ĂXXX
-[ I ]-
Processor interrupts program scan to update Input Image
Table with data from the corresponding Module group. It is
updated before the normal I/O scan and executed each
program scan.
-(IOT)- IMMEDIATE OUTPUT ąXXX
-(IOT)-
When the rung is TRUE, Processor interrupts program
scan to update Module group with data from corresponding
Output Image Table word address. It is updated before the
normal I/O scan and executed each program scan when
the rung is TRUE. Can be programmed unconditionally.
7.3
Programming Immediate I/O
Instructions