3. Instructions
566
CS/CJ/NSJ Series Instructions Reference Manual (W474)
z Operand Specifications
Flags
Function
SREAD(639) reads the data from the address specified by the stack pointer (TB+3 and TB+2) minus
the offset value in C. SREAD(639) does not change the data in the stack or the stack pointer.
The stack must be defined in advance with SSET(630).
Hint
SREAD(639) can be used to read the data for an item currently on a conveyor. The position of the
desired item is simply the number of items back (the offset value) from the most recent item added to
the conveyor.
Area
Word addresses
Indirect DM/EM
addresses
Con-
stants
Registers Flags
Pulse
bits
TR
bits
CIO WR HR AR T C DM EM
@DM
@EM
*DM
*EM
DR IR
Indirect
using IR
TK CF
TB
OK OK OK OK OK OK OK OK OK OK
--- ---
--- OK --- --- --- ---C OK
OK
D ---
Name Label Operation
Error Flag P_ER • ON if the specified read location is not within the stack area.
• ON if the offset value specified in C is 0 or greater than the maximum data region size (FFFB hex).
• ON if the contents of the stack pointer (TB+3 and TB+2) is less than or equal to the PLC memory
address of first word in the data region of the stack (TB+4). (This is a stack underflow error.)
• OFF in all other cases.
Equal Flag P_EQ • ON if the output data in D is 0.
• OFF in all other cases.
A
A
B
C
TB
TB+1
TB+2
TB+3
TB+4
D
m
n
C
n
m
PLC memory
address
Pointer
Reads the data (A) in the specified
word and outputs that data to D.
The address of the desired word is
calculated by subtracting the offset
value from the stack pointer address.
Last word
in stack
Stack
Offset value
Reads the data (A) without
changing the stack pointer.
The data (A) is
not changed.
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