Rockwell Automation 1747-PT1, D1747NP002 Hand-Held Terminal - Manual (Page 370)

Chapter 27
The Status File
27–2
The following tables describe the status file functions, beginning at address
S:0 and ending at address S:32. If a bullet (
•
) is present in the columns
headed SLC 5/02 and SLC 5/01, Fixed, the function applies to the indicated
processor(s).
Address Description 5/02
5/01,
Fixed
S:0 Arithmetic Flags
Read/write. The arithmetic flags are assessed by the processor
following the execution of any math, logical, or move instruction. The
state of these bits remains in effect until the next math, logical, or
move instruction in the program is executed.
• •
S:0/0 Carry Bit
This bit is set by the processor if a mathematical carry or borrow is
generated. Otherwise the bit remains cleared. This bit is assessed
as if a function of unsigned math.
• •
When an STI, I/O Slot, or Fault Routine interrupts normal execution of
your program, the original value of S:0/0 is restored when execution
resumes.
•
S:0/1 Overflow Bit
This bit is set by the processor when the result of a mathematical
operation does not fit in its destination. Otherwise the bit remains
cleared. Whenever this bit is set, the overflow trap bit S:5/0 is also
set (refer to S:5/0).
• •
When an STI, I/O Slot or Fault Routine interrupts normal execution of
your program, the original value of S:0/1 is restored when execution
resumes.
•
S:0/2 Zero Bit
This bit is set by the processor when the result of a math, logical, or
move instruction is zero. Otherwise the bit remains cleared.
• •
When an STI, I/O Slot, or Fault Routine interrupts normal execution of
your program, the original value of S:0/2 is restored when execution
resumes.
•
S:0/3
Sign Bit
This bit is set by the processor when the result of a math, logical, or
move instruction is negative. Otherwise the bit remains cleared.
• •
When an STI, I/O Slot, or Fault Routine interrupts normal execution of
your program, the original value of S:0/3 is restored when execution
resumes.
•
S:0/4 to
S:0/15
Reserved
• •