Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 76)

Installing the Assembly
Chapter 6
6Ć26
Connecting the Tachometer
Figure 6.15 shows details of how to connect the tachometer. Follow these
steps:
Figure 6.15
Connection Details for Tachometer
1
2
3
4
5
6
7
8
9
10
11
12
Right Wiring Arm
of 1771 - ES Expander
Servo Drive
High
(+)
Low
(-)
Tach
27K
High
Low
50V Max
at Terminals
12025
Ω
1. Connect the tachometer directly to the servo drive.
2. Connect the tachometer signal at the servo drive to the right wiring
arm of the 1771-ES expander. This allows the 1771-ES expander to
detect loss of tachometer feedback at the servo drive. Limit the
voltage at the terminals to 50V maximum. Tachometers typically
generate much larger voltages than 50V at high speed. Therefore,
you must drop the voltage thru a voltage divider.
3. Unless you have access to a voltage divider in the servo drive, place
a 27k ohms 1/4 Watt potentiometer between the servo drive and
terminal 11 of the 1771-ES expander.
4. Set the potentiometer for maximum resistance until you perform the
integration procedures (chapter 9).