Function description
Operating Manual PSSu E S INC 24V se(-T)
1001380-EN-04
14
4.2.2.3
Overflow
In both operating modes the counter can accept values from 0000 0000
H
to FFFF FFFF
H
.
}
With an underflow the value drops below 0000 0000
H
and the counter continues from
FFFF FFFF
H
.
}
With an overflow the value FFFF FFFF
H
is exceeded and the counter continues from
0000 0000
H
.
The overflow or underflow is signalled to the head module as status information.
The status information overflow is reset:
}
if the value again falls below 0000 0000
H
(underflow).
}
if 5555 0000
H
is exceeded (the lower third of the value range).
The status information underflow is reset:
}
if FFFF FFFF
H
is exceeded again (overflow).
}
if AAAA FFFF
H
is exceeded (the upper third of the value range).
4.2.3
Incremental encoder operating mode
The counter outputs and the output for the incremental encoder's zero pulse are connected
to the single-pole inputs (A, B, C).
}
Inputs A, B
The first channel of the encoder is connected to input A, the second to input B. The
second channel is 90° out of phase. If channel A is leading, the module counts for-
wards. If channel A is lagging, the module counts backwards (see timing diagram).
}
Input C
The output for the incremental encoder's zero pulse is connected to input C. An incre-
mental encoder typically supplies one zero pulse per rotation. If the zero pulse function
is activated, the module copies the last value prior to the zero pulse into the latch
memory and passes it to the process image of inputs (see chapter entitled "Transfer
counter status via latch pulse").
G
L
a
b
c
d
e
C
A
B
Legend:
}
a: The counter counts backwards because the signal at channel A is lagging.
}
b: The module has received a zero pulse. Provided the function is activated, the
counter value is copied into the latch memory with a rising edge at input C.
}
c: The counter counts forwards because the signal at channel A is leading.
}
d: The module has received a latch pulse. Provided the function is activated, the
counter value is copied into the latch memory with a rising edge at input L.
