18
1 FUNCTIONS
1.2 Selecting a Counter Type
Ring counter function
Operation of the ring counter
This function repeatedly counts pulses between the values stored in CH1 Ring counter lower limit value setting (Un\G20 to
Un\G21) and CH1 Ring counter upper limit value setting (Un\G22 to Un\G23). When the ring counter function is selected, an
overflow error does not occur. The preset function and coincidence output function can be used with this function.
Count range of the ring counter
The count range is determined by the relationship between the ring counter lower limit value or ring counter upper limit value
and the value in CH1 Present value (Un\G2 to Un\G3) when CH1 Count enable command (Y4) is turned on or when the
preset function is performed. Normally, the count range is Ring counter lower limit value Present value Ring counter upper
limit value.
■When the count range is Ring counter lower limit value Present value Ring counter upper
limit value (normally used)
• When pulses are counted up, the ring counter lower limit value is automatically stored in CH1 Present value (Un\G2 to
Un\G3) when the present value reaches the ring counter upper limit value.
• When pulses are counted down, even when the present value reaches the ring counter lower limit value, the ring counter
lower limit value is held as the lower limit, and the value of Ring counter upper limit value - 1 is stored in CH1 Present value
(Un\G2 to Un\G3) at the next count-down pulse input.
Both when pulses are counted up and when pulses are counted down, the ring counter upper limit value is not stored in CH1
Present value (Un\G2 to Un\G3). For example, when the count enable command is valid while the ring counter lower limit
value is 0, the ring counter upper limit value is 2000, and the present value is 500, the count range and the present value will
change as follows.
+2147483647
-2147483648
0
CH1
Ring counter upper limit (Un\G22 to Un\G23)
CH1
Ring counter lower limit (Un\G20 to Un\G21)
Present counter value
Counting up
Counting down
-2147483648
0
500
2000
2147483647
(2000)
500 501 1998 1999 0 1 2 498 499
Ring counter
lower limit value
Present value
Ring counter
upper limit value
Ring counter
lower limit value
to to
Ring counter upper
limit value
The ring counter upper limit value,
2000, is not stored in CH1 Present
value (Un\G2 to Un\G3).
Present value
Counting range
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