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CHAPTER 8 FUNCTIONS
8
8.2 Selecting Counter Type
8.2.2 Ring counter function
(b) When the count range is "Present value < Ring counter lower limit value or ring
counter upper limit value < Present value"
• For up count
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 "Ring counter upper limit value + 1" is stored in CH Present value (Un\G2,
Un\G3, Un\G34, Un\G35) at the next count-up pulse input.
• For down count
When the present value reaches the ring counter upper limit value, the ring counter lower limit value is
automatically stored in CH Present value (Un\G2, Un\G3, Un\G34, Un\G35).
Both in up count and in down count, the ring counter upper limit value is not stored in CH Present value
(Un\G2, Un\G3, Un\G34, Un\G35).
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 3000, the count range and the present value will
change as follows.
(c) When the count range is "Ring counter lower limit value = Ring counter upper limit
value"
When this condition is established, the count range will be the full range (-2147483648 to 2147483647) which
can be expressed in 32-bit signed binary regardless of the present value.
● While CH Count enable command (Y4, YC) is on, even if a value is written to CH Ring counter lower limit (Un\G20,
Un\G21, Un\G52, Un\G53) or CH Ring counter upper limit (Un\G22, Un\G23, Un\G54, Un\G55), the stored value does
not change.
Turn off CH Count enable command (Y4, YC) before changing the ring counter upper/lower limit value.
● Turn off CH Count enable command (Y4, YC) before changing the count range by the preset function.
-2147483648
Ring counter
lower limit value
Present value
Ring counter
upper limit value
0
3000
2000
2147483647
Ring counter
lower limit value
Ring counter
upper limit value
(2000)
Present value
3000 3001 2001to -2 -1 0 to2002 2998
2147483647 -2147483648
to 2999
Counting range
Counting range
The ring counter upper limit value,
2000, is not stored in CH
Present value (Un\G2, Un\G3,
Un\G34, Un\G35).