Readhead Set-Up; Reference Mark Set-Up - Renishaw RGH34 Installation Manual

Readhead set-up

When mounting the readhead, ensure that the scale, readhead optical window and mounting
surfaces are clean and free from obstructions.
NOTE: Refer to 'Maintenance and cleaning' section of this manual for cleaning instructions.
Adjusting set-up
Once the readhead is positioned, the rideheight, pitch, yaw and roll of the unit may need to be
adjusted to achieve optimum signal strength. It should be noted that the readhead and interface
must be properly connected to the power supply to enable the set-up LED to be used.
Confirming set-up
For reliable operation, the LED should be Green when the readhead is moved slowly
(<1 m/s) along the full axis travel.
NOTE: The set-up LED will not indicate an optimised set-up over the reference mark.
For further details, refer also to 'Reference mark set-up'.
The set-up LED will exhibit one of three colours during normal use;
Green Orange Red
Set-up tolerances
Roll
0° ±1°
Rideheight
1.5 mm ±0.15 mm
RGH34 RGS40 installation guide
Yaw
0° ±1°
Pitch
0° ±1°

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 repeatability 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.
NOTE: Check that the reference mark sensing option has been specified on the RGH34 and RGI34 that you
have purchased.
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 the set-up LED
flashes Orange or goes Blank, the reference mark adjuster screw should be turned anti-clockwise by
and the procedure repeated until a Red flash is obtained.
NOTE: If the readhead mounting is disturbed at any time, the reference mark will have to be re-phased.
A reference pulse is output in both directions, but because the reference mark can only be phased for
one direction of traverse, any indication from the LED when the readhead is
moved in the reverse direction is to be ignored. LED flash duration
is a constant 0.25 seconds, regardless of traverse speed.
LED repeater (external LED driver) signals will mimic
the on-board LED apart from the 'Blank' condition.
The repeater LED will go Blank when the
incremental output is in error (3-state).
LED flash during reference mark
traverse only
Red Orange Blank
1
turn
8
1
turn
8
8