MELSEC-A
5. PULSE INPUT AND COUNTING METHOD
5 - 1
5. PULSE INPUT AND COUNTING METHOD
This chapter describes the pulse input and counting modes of the high-speed counter
module.
(1) The pulse input mode is classified into 1-phase pulse input and 2-phase pulse
input. 1-phase pulse input is subdivided into multiplication by one and
multiplication by two, whereas 2-phase pulse input covers multiplication by one,
two and four.
The following table indicates the pulse input modes and count timing.
Pulse Input Mode Count Timing
1-phase, multiplied
by one
Up counting
B
RY(n+1)3
(RY(n+1)A)
A
Counts a pulse on leading edge of phase
A.
Phase
B and RY(n+1)3 (RY(n+1)A) are off.
Down counting
B
RY(n+1)3
(RY(n+1)A)
A
Counts a pulse on trailing edge of phase
.
Phase B or RY(n+1)3 (RY(n+1)A) is on.
1-phase, multiplied
by two
Up counting
B
RY(n+1)3
(RY(n+1)A)
A
Counts a pulse on leading and trailing edges
of phase A.
Phase
B and RY(n+1)3 (RY(n+1)A) are off.
Down counting
B
RY(n+1)3
(RY(n+1)A)
A
Counts a pulse on leading and trailing edges
of phase
A.
Phase B or RY(n+1)3 (RY(n+1)A) is on.
2-phase, multiplied
by one
Up counting
A
B
Counts a pulse on leading edge of phase
A.
Count increases in response to phase differ-
ence between phases A and B.
Down counting
A
B
Counts a pulse on trailing edge of phase
.
Count decreases in response to phase differ-
ence between phases
A and B.
2-phase, multiplied
by two
Up counting
A
B
Counts a pulse on leading and trailing edges
of phase
A.
Count increases in response to phase differ-
ence between phases
A and B.
Down counting
A
B
Counts a pulse on leading and trailing edges
of phase
A.
Count decreases in response to phase differ-
ence between phases
A and B.
2-phase, multiplied
by four
Up counting
A
B
Counts a pulse on leading and trailing edges
of phases
A and B.
Count increases in response to phase differ-
ence between phases A and B.
Down counting
A
B
Counts a pulse on leading and trailing edges
of phases
A and B.
Count decreases in response to phase differ-
ence between phases
A and B.
(2) Even if the pulse input mode is changed, counting will start from the value at the
time the mode is changed.
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