Rockwell Automation 57C422B 2 Axis Servo Module - Manual (Page 14)

2-4 2-Axis Servo Module M/N 57C422B
Each axis contains two registration inputs which are
connected to faceplate LEDs. One input is used with the
feedback encoder; the other is used with the gearing
reference. These registration inputs are typically used to
strobe the feedback and/or the reference position into a
group of registers for use by application software which can
synchronize the axis to an external event. The input may be
15-24 VDC only and there is a transport delay of
approximately 25 microseconds from the time that a
registration input is asserted until the isolated signal changes
state. Refer to figure 2.3 for a typical input circuit. In critical
applications, hard-wire your overtravel L/S into the
emergency stop circuit so that the drive will be disabled
regardless of the state of the control.
Figure 2.2 – Encoder Input Circuit