Mitsubishi Electric MELSEC-L Series LD40PD01, User Manual

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9 CREATING A HARDWARE LOGIC
9.2 Multi Function Counter Block
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9
Addition mode
When "Add Mode" is set to "ON", the following operations are performed.
• For the count in clock cycles, a value set as the addition value is added per clock cycle.
• For counting input pulses, a value set with "Add Value" is added when an addition pulse is input and a value set with "Add
Value" is subtracted when a subtraction pulse is input.
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When the addition mode is on in the linear counter mode
When the addition mode is on in the linear counter mode, the count value does not change even if the count operation is
performed with the following status.
"Count Value" + "Add Value" > "Upper Limit"
Ex.
When "Add Value" is 5, "Upper Limit" is 1000, and "Count Value" is 998 in a 32-bit signed counter timer block, "Count Value"
remains 998 even if up count is performed, and an overflow occurs.
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When the addition mode is on in the ring counter mode
When the addition mode is on in the ring counter mode and up count is performed in the status in which the total of "Count
Value" and "Add Value" exceeds "Upper Limit", the count value is as follows.
Count value after addition = "Lower Limit" + ("Add Value" - ("Upper Limit" - Current count value))
Ex.
When "Add Value" is 5, "Upper Limit" is 1000, "Lower Limit" is 0, "Count Value" is 998, and up count is performed, the current
count value becomes 3.
To turn on the addition mode in the ring counter mode, set a value which satisfies the following condition for
"Add Value". When a value which does not satisfy the following condition is set, "Count Value" may exceed
"Upper Limit" or fall below "Lower Limit".
• "Add Value" < ("Upper Limit" - "Lower Limit")
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When a buffer memory address is assigned to the addition value
When a buffer memory address is assigned to the addition value and the buffer memory address is changed with a program,
handle the buffer memory value in hexadecimal to change the value with a program.