Omron SYSMAC CJ - REFERENCE MANUAL 08-2008 Reference Manual page 754

Table Data Processing Instructions
Description
Flags
Precautions
714
Area
Index Registers
Indirect addressing
using Index Registers
LIFO(634) reads the data from the address indicated by the stack pointer (the
newest word of data in the stack), decrements the stack pointer by one, and
outputs the data to D. The word that was read is left unchanged.
TB
Stack
TB+1
pointer
TB+2
TB+3
Use LIFO(634) in combination with PUSH(632). After PUSH(632) has been
used to write data into a stack, LIFO(634) can be used to read data from the
stack on a last-in first-out basis. After data is stored by PUSH(632), the stack
pointer indicates the address next to the last data.
Name Label
Error Flag ER
The stack must be defined in advance with SSET(630).
TB
---
,IR0 to ,IR15
–2048 to +2047 ,IR0 to –2048 to +2047 ,IR15
DR0 to DR15, IR0 to IR15
,IR0+(++) to ,IR15+(++)
,–(– –)IR0 to, –(– –)IR15
PC memory
address
TB
Newest
TB+1
data
TB+2
m–1
TB+3
Stack
pointer
m–1
Reading
The pointer is
decremented.
Operation
ON if the contents of the stack pointer (TB+3 and TB+2) is
less than or equal to the PLC memory address of first
word in the data region of the stack (TB+4).
(This is a stack underflow error.)
OFF in all other cases.
Section 3-17
D
PC memory
address
m–1
A is left unchanged.