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Timer/Counter Function Blocks Section 3-4
Timing Charts
3-4-6 Serial-Parallel Converter
Basic Function Counts the number of input signals and outputs the count value.
Diagram
General Description The Serial-Parallel Converter function block counts the number of input sig-
nals and outputs the count value on outputs 1 to 8. The count value is the
number of times the Input signal changes from OFF to ON. To detect changes
in the Input signal, the OFF time and ON time of the Input signal must both
continue at least as long as the cycle time.
Counting Method An incremental counter is always used. The initial count value is 0 and the
count value is incremented each time the rising edge (OFF to ON transition)
of the Input signal is detected. The maximum count value is 255. If an Input
signal is detected when the count value is 255, the count value will become 0.
Reset Method Only the manual reset can be used to reset the number of times that inputs
were counted. The present value of the counter is reset to 0 when the Reset
signal turns ON. Input pulses will not be counted while the Reset signal is ON.
Counting will be resumed when the Reset signal turns OFF. Counting will be
resumed the next cycle after the Reset signal turns OFF and the input signal
turns ON.
Count Output The 8-bit count value is output to outputs 1 to 8. The relationship between the
count value and outputs 1 to 8 is shown in the following table.
IDLE to RUN
Increment
input
Decrement
input
Present value
Counter
(Set value)
Output
Enable
Maximum Number of Outputs (default)
Output signal Output value
Output 1 Bit 0 of the count value
Output 2 Bit 1 of the count value
Output 3 Bit 2 of the count value
Output 4 Bit 3 of the count value
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