7-3
Section
Counter Units
139
The following count modes can be used with the Counter Unit.
Note
If the count mode is changed during count operations, the present value will be
cleared to 0.
Differential Phase Pulse Inputs
When the A phase is 90
_
in advance of the B phase, the input is read as forward
rotation and the count is incremented. When the A phase is 90
_
behind the B
phase, the input is read as reverse rotation and the count is decremented. When
input is made with differential phase pulse input, the multiple function (
×
1,
×
4)
can be used. The following table shows how the multiple function will operate
according to the phases of A and B.
Multiple function
A phase 90
_
ahead
A phase 90
_
behind
×
1
Count is incremented at
rising edge of A-phase input
Count is decremented at
falling edge of A-phase input
×
4
Count is incremented at
rising edge and falling edge
of A-phase input and
B-phase input
Count is decremented at
rising edge and falling edge
of A-phase input and
B-phase input
A phase 90
_
ahead
A phase 90
_
behind
A phase
B phase
Multiplier
Note
When using differential phase pulse input at a multiple function setting of
×
4, the
count number for each revolution of the encoder will be 4 times the resolution of
the encoder. Use an encoder that is compatible with the counting range.
Pulse and Direction Inputs
Phase A is a pulse signal and phase B is a direction signal. Counting will operate
in the following way.
Phase B OFF
Phase B ON
Count is incremented at the rising edge
of the A-phase input
Count is decremented at the rising edge
of the A-phase input
B phase OFF
B phase ON
A phase
B phase
Incrementing
Decrementing
Note
Switching B phase (direction input) ON and OFF, must be carried out with A
phase (pulse input) switched OFF.
Count Mode