Omron CP - PROGRAMMING MANUAL 05-2007 Programming Manual page 636

Table Data Processing Instructions
3-16-15 STACK DATA READ: SREAD(639)
Purpose
Ladder Symbol
Variations
Applicable Program Areas
Operands
Reads the data from the specified data element in the stack. The offset value
indicates the location of the desired data element (how many data elements
before the current pointer position).
SREAD(639)
TB
C
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.
15
TB+4 Data storage region
TB+(N–1)
TB: First stack address
C: Offset value
D: Destination word
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.)
0
Section 3-16
SREAD(639)
@SREAD(639)
Not supported.
Interrupt tasks
OK
603