Programming Reference
B–3
Status File Descriptions
The following tables describe the status file functions, beginning at address S:0 and
ending at address S:32.
Each status bit is classified as one of the following:
•
Status — Use these words, bytes, or bits to monitor controller operation or
controller status information. The information is seldom written to by the user
program or programming device (unless you want to reset or clear a function
such as a monitor bit).
•
Dynamic Configuration — Use these words, bytes, or bits to select controller
options while online with the controller.
•
Static Configuration — Use these words, bytes, or bits to select controller
options while in the offline program mode, prior to downloading the user
program.
Address
Bit
Classification
Description
S:0
Arithmetic and
Scan Status
Flags
The arithmetic flags are assessed by the
controller following the execution of certain
math and data handling instructions. The state
of these bits remain in effect until certain math
or data handling instructions in the program
are executed.
S:0/0
Carry
Status
This bit is set by the controller 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 a STI, high-speed counter, 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
Status
This bit is set by the controller 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 except for the ENC bit. Refer
to S:5/0. When a STI, high-speed counter, or
Fault Routine interrupts normal execution of
your program, the original value of S:0/1 is
restored when execution resumes.
Reference
efesotomasyon.com - Allen Bradley,Rockwell,plc,servo,drive
