Rockwell Automation 8520 9/Series CNC Integration Maintenance Manual Documentation Set - Manual (Page 225)

Section 4C
Connecting the 4-axis Servo Module
4C-27
Connect a touch probe to the connector labeled BAT/TP on the servo
module (TB1). Connector terminal identification is provided in
Figure 4C.18. Touch probe cable information can be found on
page 7A-38.
The time delay between the servo module receiving the touch probe trigger
and latching the current axis position is negligible. However, you should
be aware of any external delays that may introduce position “staleness” in
the probing operation, especially at high probing speeds.
It is a good idea to establish an offset for the distance between the actual
location, as sensed by the probe at a very low speed, and the location
sensed by the probe at the intended probing speed. The offset can then be
added or subtracted to any future values obtained through probing. This
helps make sure that if there are any external delays in the trigger signal,
the position staleness shows up as a constant position offset error and is
removed from the measurement (assuming the external delay is
repeatable).
The motion controller touch probe interface is intended for use with units
that offer 5V dc compatible solid state relay outputs (see Figure 4C.19).
Other configurations can be supported as long as the user operates within
the published electrical specifications.
The touch probe circuitry resident on the servo module only responds to
the trigger probe edge changes. Polarity transition (high to low or low to
high) is selectable through the AMP parameter Probe Transition. Specify
the probe transition in AMP as rising edge or falling edge. Once the active
edge occurs, position data is captured by the module, and additional
occurrences of the trigger signal have no effect until the probe is reenabled
under program control.
Refer to the 9/Series CNC 9/230,9/260, and 9/290 AMP Reference
Manual, publication 8520-6.4, for more information.
ATTENTION: It is preferred, from a safety standpoint, that the
touch probe relay be closed at rest and open when the touch
probe stylus deflects. Then, if a wire breaks or shorts to ground,
it will appear to the system as a probe fired and the probing
cycle in process will stop commanding motion towards the part.
The user should make every effort towards the fail-safe
operation of the touch probe. Not all vendor’s touch probe
control units conform to this safety consideration.
4C.8
Wiring a Touch Probe to the
Servo Module