Omron DEVICENET#05-2003 Operation Manual page 187

GT1-CT01 Counter Unit
Count Mode
A phase
B phase
Multiplier
A phase
B phase
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 for-
ward 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 decre-
mented. 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
1
4
A phase 90 ahead
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 resolu-
tion 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
Count is incremented at the rising edge of
the A-phase input
B phase OFF
Incrementing
Note Switching B phase (direction input) ON and OFF, must be carried out with A
phase (pulse input) switched OFF.
A phase 90 ahead
Count is incremented at rising
edge of A-phase input
Count is incremented at rising
edge and falling edge of A-
phase input and B-phase input
Count is decremented at the rising edge
of the A-phase input
B phase ON
Section 5-4
A phase 90 behind
Count is decremented at falling
edge of A-phase input
Count is decremented at rising
edge and falling edge of A-
phase input and B-phase input
A phase 90 behind
Phase B ON
Decrementing
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