Allen-Bradley SLC 500 Series User Manual

Publication 1747-RM001G-EN-P - November 2008
5-28 Data Handling Instructions
LIFO Load (LFL) and LIFO
Unload (LFU)
LFL and LFU instructions are used in pairs. The LFL instruction loads words
into a user-created file called a LIFO stack. The LFU instruction unloads
words from the LIFO stack in the opposite order as they were entered.
Instruction parameters have been programmed in the LFL - LFU instruction
pair shown below.
EN
DN
EM
LFL
LIFO Load
Source N7:71
LIFO #N7:80
Control R6:1
Length 10<
Position 0<
LFL
EU
DN
EM
LFU
LIFO Unload
LIFO #N7:80
Dest N7:72
Control R6:1
Length 10<
Position 0<
LFU
Output Instruction
Fixed SLC
5/01
SLC
5/02
SLC
5/03
SLC
5/04
SLC
5/05
••••
Table 5.20 Instruction Function
Destination Position
N7:11 N7:12 0
N7:13 1
LFU instruction
unloads data from
stack #N7:12 at
position 8.
N7:14 2
3
4
5 34 words are allocated for FIFO
stack starting at N7:12, ending at
N7:45
6
7
Source 8
N7:10 9
LFL instruction loads
data into stack
#N7:12 at the next
available position, 9
in this case.
N7:45 33
Loading and Unloading of Stack #N7:12
(DN)
(EN)
(DN)
(EM)
LFL
LIFO LOAD
Source N7:10
LIFO #N7:12
Control R6:0
Length 34
Position 9
(EU)
(EM)
LFU
LIFO UNLOAD
LIFO #N7:12
Dest N7:11
Control R6:0
Length 34
Position 9

Allen-Bradley SLC 500 Series Specifications

General

Brand	Allen-Bradley
Model	SLC 500 Series
Category	Controller
Language	English