166 Rockwell Automation Publication 7000-UM202D-EN-P - May 2018
Chapter 3 Control Component Definition and Maintenance
2. Data Polarity: Absolute encoders typically have a High True output. If
the encoder model does not have a High/True (or Non Inverted/
Inverted) option, you should assume it to be High True. In the case of a
10bit High True encoder, the zero position is represented by
0000000000. In a Low/True encoder, the zero position is 1111111111.
On the Universal Encoder Interface, the position data is inverted in
hardware. That is, a ‘1’ will turn on an optocoupler producing a ‘0’.
Therefore, a High True encoder would produce 1111111111 for the
zero position. With the POL_QRDNT jumper, you can control the
polarity of the input. With the jumper installed (factory default), it is set
to accept High True encoders, and an extra inversion is done in the
Universal Encoder Interface. If you are using a Low True encoder, then
this jumper needs to be removed so that the zero position is inverted by
the optocouplers alone.
The other role of the POL_QRDNT jumper is to correct the data in the
event the encoder was mounted so that a CCW rotation produced
decreasing counts. If this is the case, the POL_QRDNT jumper should
be configured to the opposite of what it should normally be for the data
polarity. For example, if the Universal Encoder Interface is configured to
operate with High True encoders (POL_QRDNT installed), remove it
to correct for encoder mounting.
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