Stack Size Read: Snum(638) - Omron SYSMAC CJ - REFERENCE MANUAL 01-2008 Reference Manual

Table Data Processing Instructions

3-17-14 STACK SIZE READ: SNUM(638)

Purpose
Ladder Symbol
Variations
Applicable Program Areas
Operands
Counts the amount of stack data (number of words) in the specified stack.
This instruction is supported by CS1-H, CJ1-H, CJ1M, and CS1D CPU Units
only.
SNUM(638)
TB: First stack address
TB
D: Destination word
D
Variations Executed Each Cycle for ON Condition
Executed Once for Upward Differentiation
Executed Once for Downward Differentiation Not supported.
Immediate Refreshing Specification
Block program areas
OK OK
TB through TB+3: Stack control words
The first four words of the stack contain the PLC memory address of the last
word in the stack and the stack pointer (the PLC memory address of the next
available word in the stack.)
15
TB
15
TB+1
15
TB+2
15
TB+3
TB+4 through TB+(N–1): Data storage region
The remainder of the stack is used to store data.
TB+(N–1)
Step program areas Subroutines
OK
0
PLC memory address of the last
word in the stack (rightmost 4 digits)
0
PLC memory address of the last
word in the stack (leftmost 4 digits)
0
Stack pointer (rightmost 4 digits)
(Initial value is the rightmost 4 digits of
the PLC memory address for TB+4.)
0
Stack pointer (leftmost 4 digits)
(Initial value is the leftmost 4 digits of
the PLC memory address for TB+4.)
15
TB+4
Data storage region
Section 3-17
SNUM(638)
@SNUM(638)
Not supported.
Interrupt tasks
OK
0
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