Publication 1763-RM001C-EN-P - October 2009
File Instructions
237
•
Control - This is a control file address. The status bits, stack length,
and the position value are stored in this element. The control
element consists of 3 words:
•
Length - The length operand contains the number of elements in the
LIFO stack. The length of the stack can range from 1 to 128 (word)
or 1 to 64 (long word).
•
Position - This is the next location in the LIFO stack where data will
be unloaded. Position is a component of the control register. The
position can range from 0 to 127 (word) or 0 to 63 (long word). The
position is decremented after each unload.
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
Word 0
--
EU
(1)
(1) EU - Enable Unload Bit is set on false-to-true transition of the rung and indicates the instruction is enabled.
DN
(2)
(2) DN - Done Bit, when set, indicates that the stack is full.
EM
(3)
(3) EM - Empty Bit, when set, indicates LIFO is empty.
not used
Word 1
Length - maximum number of words or double words in the stack.
Word 2
Position - the next available location where the instruction unloads data.
LFU Instruction Valid Addressing Modes and File Types
For definitions of the terms used in this table see Using the Instruction Descriptions on page 82.
Parameter
Data Files
Function Files
CS
-
Comms
IO
S -
I/
O
DL
S
-
D
a
ta
L
o
g
Address
Mode
(1)
Address Level
O
I
S
B
T,
C
, R
N
F
ST
L
MG,
PD
RI/
R
IX
PL
S
RTC
HS
C
PTO, PWM
STI
EII
BH
I
MMI
LC
D
Imme
diate
Di
re
c
t
Indir
e
c
t
Bi
t
Wo
rd
Long
W
o
rd
Eleme
n
t
LIFO
•
•
•
•
•
•
•
•
•
•
Destination
•
•
•
•
•
•
•
•
•
•
•
Control
(2)
•
•
Length
•
•
Position
•
•
(1) See Important note about indirect addressing.
(2) Control file only. Not valid for Timers and Counters.
IMPORTANT
You cannot use indirect addressing with: S, ST, MG, PD,
RTC, HSC, PTO, PWM, STI, EII, BHI, MMI, CS, IOS, and
DLS files.
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive