Mitsubishi Electric MELSEC-L Series LD40PD01 User Manual page 158

■Upper limit value ≤ Lower limit value
When "Count Value" has reached the value of "Upper Limit" -1, "Lower Limit" is stored in "Count Value" in the next up count.
When "Count Value" has reached the "Lower Limit", the value of "Upper Limit" - 1 is stored in "Count Value" in the next down
count. When the same values are set to "Upper Limit" and "Lower Limit", pulses can be counted within the entire range of 32-
bit signed/unsigned and the 16-bit signed/unsigned values
The following figure shows a count operation example for a 16-bit unsigned counter block.
0 "Upper Limit" - 1 "Lower Limit"
Counting
(2)
(1)
(1) When the count value is counted down from 0, the value becomes 65535. When the count value is counted up from 65535, the value becomes 0.
(2) When the count value is counted down from "Lower Limit", the value becomes "Upper Limit" - 1. When the count value is counted up from "Upper Limit" -
1, the value becomes "Lower Limit".
In the ring counter mode, set the values as follows.
• Make sure that the count value is within the count range set with the upper limit value and lower limit value.
If the count value exceeds the count range, set the preset value within the count range and perform the
preset function. If the count operation is continued with the count value out of the count range, the operation
cannot be guaranteed.
• Set the preset value within the count range set with the upper limit value and lower limit value.
9 CREATING A HARDWARE LOGIC
156
9.2 Multi Function Counter Block
65535
Counting