Installation manual

Publication 1747-RM001G-EN-P - November 2008
SLC Status File B-19
S:3L Status Current/Last 10 ms Scan Time
The value of this byte tells you how much time elapses in a
program cycle. A program cycle includes:
• scanning the ladder program,
• housekeeping,
• scanning the I/O, and
• servicing of the communication port.
The byte value is zeroed by the processor each scan,
immediately preceding the execution of rung 0 of program file
2 (main program file) or on return from the REF instruction. The
byte is incremented every 10 ms thereafter, and indicates, in
10 ms increments, the amount of time elapsed in each program
cycle. If this value ever equals the value in S:3H Watchdog, a
user watchdog major error will be declared (code 0022).
The resolution of the scan time value is+ 0 to -10 ms. Example:
The value 9 indicates that 80-90 ms has elapsed since the start
of the program cycle.
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TIP
When SVC or REF instructions are contained in your program,
this value will appear to be erratic when you monitor it with a
programming device. This is because the SVC or REF
instructions allow this value to be read in mid-scan, while it is
still incrementing.
••••
Table B.2 Status File Functions (Continued)
Address Classification Description Fixed
5/01
5/02 5/03 5/04 5/05