Rockwell Automation 8520 9/Series Hardware TAB 5 - Manual (Page 107)

Section 5B
9/440HR CNC/Drive System
5B-33
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 5B.22 shows a typical wiring diagram compatible
with most probe designs configured to trigger on the rising edge of the
probes signal.
Figure 5B.22
Typical Wiring of a Touch Probe Configured for Rising Edge Trigger
9/440HR Wiring Board
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