Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 227)

Section 4C
Connecting the 4-axis Servo Module
4C-29
To avoid misfires use the threshold values from the above table to
determine the necessary signal voltage for steady state operation (probe not
fired). For probes configured to fire on the falling edge the steady state
voltage must remain above 3.06 volts. For probes configured to fire on the
rising edge the steady state voltage must remain below 2.18 volts.
Wiring a Probe for Rising Edge Configurations
Typical wiring of a simple contactor type touch probe configured to fire on
the rising edge of the probe signal, requires the addition of a 1000 ohm pull
down resistor. Figure 4C.20 shows a typical wiring diagram compatible
with most probe designs configured to trigger on the rising edge of the
probes signal.
Figure 4C.20
Typical Wiring of a Touch Probe Configured for Rising Edge Trigger
Servo Module
470 ohm
5V common
1000 ohm
+5 V dc
1000 ohm
pull down resistor
(customer supplied)
Probe Contact
to encoder interface 4
3
2
1