Emerson PACSystems RSTi-EP - Page 234

User Manual Section 5
GFK-2958L May 2021
Detailed Description of I/O Modules 220
Counting Range
Limits
Valid range of values
End value
–2 147 483 648 (–2
31
) to +2 147 483 647 (2
31
– 2)
Upper count limit
+2 147 483 647 (2
31
-1)
Periodic Counting/ No Primary Direction
Figure 114: Periodic Counting, No Primary Direction
•
Counting (up or down) starts at the load value, the entire counting range is used.
•
Upon reaching a count limit, the counter jumps to the load value and starts counting
again from there. The status bit Overflow performed, or Underflow performed is set and
a process alarm will be triggered if it is parameterized. All status bits remain set until
they are reset with the bit Reset status bits in the control word.
Periodic Counting/ Primary Counting Direction Up
Figure 115: Periodic Counting, Primary Counting Direction Up
•
Up-counting starts at the load value.
•
If the parameterized end value -1 is reached during counting in the positive direction,
the counter jumps back to the load value at the next positive count pulse and continues
counting from there. The status bit End value reached is set and a process alarm will be
triggered if it is parameterized.
•
Upon reaching the lower count limit the counter jumps to the upper count limit to
continue counting from there. The status bit Underflow performed is set and a process
alarm will be triggered if it is parameterized. All status bits remain set until they are reset
with the bit Reset status bits in the control word.