Rockwell Automation 1746-HSCE2 Multi-Channel High Speed Counter Module - Manual (Page 123)

1 Publication 1746-UM002B-EN-P - August 2004
Appendix
B
Connecting a Differential Encoder
This appendix describes the wiring procedures for connecting a
differential encoder to the 1746-HSCE2 module.
For proper module operation, wire the encoder so that the Z input
signal is high (true) at the same time the A and B input signals are low
(false). If this condition is not met, inconsistent homing may occur.
If you are using an Allen-Bradley Bulletin 845H differential encoder,
this condition is met by following the wiring diagrams in the manual.
The following five steps describe how to connect a differential
encoder to the module.
1. Obtain the encoder output timing diagram from the encoder
data sheets. The timing diagram for the 845H encoder is shown
below for example purposes only.
Figure B.1 845H Encoder Timing Diagram
2. Look at the Z input signal and its complement Z signal on the
timing diagram. Whichever signal is low for most of the encoder
revolution and pulses high for the marker interval should be
wired into the Z(+) terminal. The remaining signal should be
wired into the Z(-) terminal.
3. Look at the B input signal and its complement B signal.
Whichever signal is low for at least part of the marker interval
should be wired to the B(+) terminal. If both signals meet this
condition, either signal may be wired to the B(+) terminal. Wire
the remaining signal to the B(-) terminal.
Counter-clockwise Rotation Shown
Channel A
Channel A
Channel B
Channel B
(Index) Channel Z
Channel Z
Logic 1
Logic 2
1 Cycle
90 ± 22°