Allen-Bradley MicroLogix 1200 Reference Manual page 197

This instruction uses the following operands:
• Source - The source operand is a constant or address of the value
used to fill the currently available position in the LIFO stack. The data
size of the source must match the LIFO stack. If LIFO is a word size
file, source must be a word value or constant. If LIFO is a long word
size file, source must be a long word value or constant. The data
range for the source is from -32768 to 32767 (word) or -2,147,483,648
to 2,147,483,647 (long word).
• LIFO - The LIFO operand is the starting address of the stack.
• 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:
15 14 13
Word 0 (1) --
EN DN
Word 1 Length - maximum number of words or long words in the stack.
Word 2 Position - the next available location where the instruction loads data.
(1) EN - Enable Bit is set on false-to-true transition of the rung and indicates the instruction is enabled.
(2) DN - Done Bit, when set, indicates that the stack is full.
(3) EM - Empty Bit, when set, indicates that LIFO is empty.
• Length - The length operand contains the number of elements in the
FIFO stack to receive the value or constant found in the source. The
length of the stack can range from 1 to 128 (word) or 1 to 64 (long
word). The position is incremented after each load.
• Position - This is the current location pointed to in the LIFO stack. It
determines the next location in the stack to receive the value or
constant found in source. Position is a component of the control
register. The position can range from 0 to 127 (word) or 0 to 63 (long
word).
12 11 10 9 8 7 6 5 4 3 2 1 0
(2) (3) not used
EM
File Instructions 14-15
Publication 1762-RM001C-EN-P