Rockwell Automation 1772-LS_LSP,D17726.8.6 PROG/OPER MANUAL-MINI PLC-2/05 - Manual (Page 263)

Quick Reference
Appendix C
CĆ7
Table C.F
Program Control 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 or 4 digits long, depending on data table size. When entering the word address, use a
leading zero if necessary.
Key Symbol Instruction Name 1770-T3 Display Explanation and Rung Conditions
-(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 MCR rung is true, each rung condition controls their
output instruction.
When the first MCR rung is false, all non-retentive bits in the
zone are reset.
WARNING: Do not overlap MCR zones, or nest with ZCL
zones. Do not jump to a 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 ZCL rung is true, all output instructions within the
zone act according to the logic conditions preceding them.
When the first ZCL rung is false, outputs in the zone will
remain in their last state.
WARNING: Do not overlap ZCL zones, or nest with MCR
zones. Do not jump to a label in ZCL zones.
-[ I ]- Immediate Input XXX
-[ 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 XXX
-(IOT)-
When rung is true, the processor interrupts program scan to
update a module group with data from its 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.