Allen-Bradley PLC-5 - Sequencer Instructions

Publication 1785-UM012D-EN-P - July 2005
Instruction Set Quick Reference D-21
Sequencer Instructions
LIFO Load
LFL
Status Bits:
EN - Enable
Load
DN - Done Bit
EM - Empty Bit
When the input conditions go from false-to-true, the controller
loads N70:1 into the next available element in the LIFO file
#N70:3, as pointed to by R6:61. Each time the rung goes from
false-to-true, the controller loads another element. When the
LIFO file (stack) is full (64 words have been loaded), the DN bit
is set.
See page F-8 for a description of prescan activities for this
instruction.
LIFO Unload
LFU
Status Bits:
EU - Enable
Unload
DN - Done Bit
EM - Empty Bit
When the input conditions go from false-to-true, the controller
unloads the last element from #N70:3 and puts it into N70:2.
Each time the rung goes from false-to-true, the controller
unloads another element.
When the LIFO file is empty, the EM
bit is set.
See page F-8 for a description of prescan activities for this
instruction.
Instruction Description
LFL
LIFO LOAD
Source
LIFO
N70:1
#N70:3
R6:61
Control
Position
Length
0
64
LFU
LIFO UNLOAD
LIFO
Dest
#N70:3
N70:2
R6:61
Control
Position
Length
0
64
Instruction Description
Sequencer Input
SQI
The SQI instruction filters the Source (I:031) input image data
through a Mask (FFF0) and compare the result to Reference data
(#N7:11) to see if the two values are equal. The operation is
controlled by the information in the control file R6:21. When the
status of all unmasked bits of the word pointed to by control
element R6:21 matches the corresponding reference bits, the
rung condition remains true if preceded by a true rung
condition.
Sequencer Load
SQL
Status Bits:
EN - Enable
DN - Done Bit
ER - Error Bit
The SQL instruction loads data into the sequencer File (#N7:20)
from the source word (I:002) by stepping through the number of
elements specified by Length (5) of the Source (I:002), starting
at the Position (0). The operation is controlled by the
information in the control file R6:22. When the rung goes from
false-to-true, the SQL instruction increments the next step in
the sequencer file and loads the data into it for every scan that
the rung remains true.
See page F-8 for a description of prescan operation for
this instruction.
SQI
SEQUENCER INPUT
File
Source
#N7:11
I:031
FFF0
R6:21
Mask
Control
Position
Length
0
4
SQL
SEQUENCER LOAD
File
Source
#N7:20
I:002
R6:22Control
Position
Length
0
5