Readhead Mounting/Installation; Limit Switch - Renishaw RCH25U30J00A Installation Manual

Readhead mounting/installation

Mounting brackets
The bracket must have a flat mounting surface, enable conformance to the installation tolerances,
allow adjustment to the rideheight of the readhead, and be sufficiently stiff to prevent deflection of the
readhead during operation. For easier installation, adjust the roll and yaw of the bracket with respect
to the axis of readhead travel before the RGH24 or RGH25 is attached. This can be done with a clock
gauge and a precision square.
Readhead set-up
To set nominal rideheight, position readhead spacer with 'L' shaped aperture under the optical
centre of the readhead to allow normal LED function during set-up procedure. Ensure that the scale,
readhead optical window and mounting face are clean and free from obstructions.
NOTE: Ensure readhead fixing screws are tightened to 0.5 Nm-0.7 Nm.
Yaw
0° ± 0.5°
Roll
Pitch
0° ± 1°
0° ± 1°
0.8 ± 0.1 mm
Rideheight
For reliable operation, the set-up LED should be GREEN when readhead is moved along the
full axis travel.
An external set-up signal (X or V ) is also available on RGB25 interfaces for use where the LED is
X
not visible. In this case, 5V indicates optimum set-up, while a 0V signal indicates that the set-up
should be adjusted. The JST version of the RGH24 has an LED repeater signal that can be used in
cases where the LED is not visible.
RGH24
Green Orange Red
RGH25 and RGB25
Green Orange Red
IMPORTANT: The RGH24 range does not incorporate a separate Alarm 'E' signal. Low signal is
indicated by a 3-state output of the line driver channels. For further details, refer to the Data sheet
Part No. L-9517-0166.

Limit switch

A limit switch signal is output when the readhead sensor passes over the magnetic actuator.
For full output specification refer to RGH24 Data sheet (Part number L- 9517- 0166) and
RGH25 Data sheet (Part number L-9517- 0168).
Reference mark set-up
To ensure unidirectional repeatability, the reference mark requires phasing with the scale in
the direction of normal datuming operation.
A reference pulse is output in both directions, but repeatabilty is guaranteed only in the
phased direction.
Ensure readhead is set up correctly with a green LED indication over the full length of travel and
that the reference mark actuator is fitted correctly.
NOTE: It is recommended that a datum procedure is performed as part of any power-up sequence
to ensure the correct datum position is recorded.
NOTE: Reference mark output is synchronised with the incremental channels, giving unit of
resolution pulse width. For further details see RGH24 and RGH25 Data sheets (L-9517-0166 and
L- 9517-0168)
Phasing procedure
The readhead must be moved over the reference mark in the direction to be used for the datuming
operation. The reference mark is phased correctly when the set-up LED flashes red for 0.25 seconds.
If it flashes orange or goes blank, the reference mark adjuster screw should
1 8
be turned anti-clockwise by turn and the procedure repeated until
a red flash is obtained.
RGH24
Red Orange Blank
LED flash during reference
mark traverse only
1 8
turn