Rockwell Automation 1771-IJ_IK IK ENCODER/COUNTER MODULES - Manual (Page 15)

2–3 Preliminary Adjustments
Publication 1771ĆUM006B-EN-P - June 2002
Figure 2.1
Input Pulses
Time
Encoder
Channel A
Channel B
x1
x2
x4
Up
Pulsed
to
Counter
Encoder
Channel A
Channel B
x1
x2
x4
Down
Pulsed
to
Counter
15945
In the counter mode, the module adds the incoming pulses on
channel A. The count is incremented on the rising edge of the pulse
(high true). The direction of the count can be controlled with either
the control word or an external switch wired to channel B. Channel
B must be left unconnected if the count direction is to be software
controlled. Typical input device counting might be high speed static
switches and incremental encoders. Mechanical switches are not
recommended as input counting devices used with the 1771-IJ
because the contact bounces might be counted as pulses. However,
the 1771-IK can be used with a mechanical switch, provided the
module is configured for mechanical counting (filter has been put in)
and the counting frequency does not exceed 50Hz. To use the
module in the counter mode, switch 4 must be set to counter (off).