Publication 1762-RM001C-EN-P
Timer and Counter Instructions 8-3
Timer Accuracy
Timer accuracy refers to the length of time between the moment a timer
instruction is enabled and the moment the timed interval is complete.
If your program scan can exceed 2.5 seconds, repeat the timer instruction
on a different rung (identical logic) in a different area of the ladder code
so that the rung is scanned within these limits.
Repeating Timer Instructions
Using the enable bit (EN) of a timer is an easy way to repeat its complex
conditional logic at another rung in your ladder program.
Table 8.4 Timer Accuracy
Time Base Accuracy
0.001 seconds -0.001 to 0.00
0.01 seconds -0.01 to 0.00
1.00 seconds -1.00 to 0.00
NOTE
Timing could be inaccurate if Jump (JMP), Label (LBL),
Jump to Subroutine (JSR), or Subroutine (SBR) instructions
skip over the rung containing a timer instruction while the
timer is timing. If the skip duration is within 2.5 seconds,
no time is lost; if the skip duration exceeds 2.5 seconds,
an undetectable timing error occurs. When using
subroutines, a timer must be scanned at least every 2.5
seconds to prevent a timing error.
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