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Basic Hardware and Function
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8. Special I/O Functions
8.3.3 Quadrature bi-pulse counter
Function
This function counts up or down the quadrature bi-pulse (2-phase pulses whose phases
are shifted 90° each other). Counts up when phase A precedes, and counts down when
phase B precedes. Both rising and falling edges of each phase are counted.
Consequently, 4 times count value against the pulse frequency is obtained.
Phase A
Phase B
Up count Down count
When the count value reaches the comparison value 1 (or 2), the I/O interrupt program
#1 (or #2) is activated (if the interrupt enable flag for each is ON).
This counter operation is enabled while the soft-gate is ON. The count value is reset to 0
when the soft-gate is changed from ON to OFF. The count value is also reset to 0 when
the reset input comes ON.
When the soft-gate is OFF, the count value can be changed by writing the data into the
comparison value 1 (or 2) register and setting the count preset flag 1 (or 2) to ON.
The comparison value 1 and 2 can be changed even when the soft-gate is ON.
The count value range is -2147483648 to 2147483647 (32-bit data).
Hardware condition
Phase A and phase B (X000 and X001)
ON/OFF pulse width: 100 ms or more (max. 5 kHz)
Reset input (X002)
ON/OFF duration: 2 ms or more
Related registers
SW16: Function selection. Refer to section 8.1.
Function Re
g
ister/device Remarks
Phase A X000
Phase B X001
Reset input X002
Comparison value 1
SW19
×
SW18
Data ran
g
e: -2147483648 to 2147483647
Comparison value 2
SW21
×
SW20
Count value
SW23
×
SW22
Soft-
g
ate S240 Operation is enabled when ON
Interrupt enable 1 S241 Interrupt 1 is enabled when ON
Count preset 1 S243 Used to preset the count value
Interrupt enable 2 S249 Interrupt 2 is enabled when ON
Count preset 2 S24B Used to preset the count value
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