Rockwell Automation 1771-QC , D17716.5.25 SER/B SERVO POS - Manual (Page 41)

Hardware Description
Chapter 5
5Ć4
Tachometer Input
Terminals 11 and 12 on the right wiring arm provide connection points for
the velocity feedback signal from the tachometer. Although the velocity
loop is closed on the servo drive, the 1771-ES expander uses the velocity
feedback signal to compare to the position feedback signal from the
encoder. If the module detects an imbalance between these signals, it
disables the servo drive and sends a loss of feedback signal through the
status block.
The 1771-ES expander accepts a full scale tachometer signal of 3V to
50V dc. If the full scale tachometer signal is greater than 50V dc, you
must reduce it through a voltage divider on the servo drive before
connecting it to the module.
CAUTION: Do not connect a signal greater than 50V dc across
these terminals. A signal greater than 50V dc could damage the
1771-ES expander.
Hardware Done Output
Terminal 7 on the right wiring arm provides a connection point for a
hardware done output signal (Figure 5.3).