VIONiC RTLC20-S installation guide
6
Reference mark selector and limit magnet
installation
IMPORTANT:
Allow 24 hours after scale application before fitting magnets.
For accuracy and ease of positioning of reference mark selector and limit magnets,
the applicator tool (A-9653-0201) should be used. The magnet should be attached
to the applicator tool as shown below. Limit magnets can be positioned at any
user‑defined location along the scale, but the reference mark selector magnet
should be positioned adjacent to the selected
IN-TRAC
reference mark as shown.
As the VIONiC readhead passes the reference mark selector magnet or limit
switch magnet, a force of up to 0.2 N is generated between the magnet and the
concentrators on the readhead. The design of the bracket should be sufficiently stiff
so that it is able to tolerate such force without distorting. Following the clamping
instructions on the scale installation will prevent this magnetic force from disturbing
the scale.
Limit trigger point
The limit output is nominally asserted when the readhead limit switch sensor
passes the limit magnet leading edge, but can trigger up to 3 mm before that edge
(see ‘RTLC20-S scale installation drawing’ on page 4)
NOTES
X
Reference and limit magnets may creep when influenced by magnetic materials
in close proximity. In such cases, they should be held in place using an
additional fillet of epoxy glue or similar along the outer edge of the magnet
assembly. Optional bolted reference and limit magnets are available.
X
The reference mark selector and limit actuator locations are correct for the
readhead orientation shown.
X
External magnetic fields greater than 6mT, in the vicinity of the readhead,
may cause false activation of the limit and reference sensors.
P limit magnet
Remove
self-adhesive
backing paper
Reference mark
selector magnet
Selected
IN-TRAC
reference mark
Q limit magnet
Applicator tool
(A 9653‑0201)
The datum clamp (A‑9585‑0028) fixes the RTLC20‑S
scale rigidly to the substrate at the location chosen.
CAUTION:
The metrology of the system may be
compromised if the datum clamp is not used.
The datum clamp does not need to be fitted adjacent to a
reference mark. It can be positioned anywhere along the
axis depending upon the customers’ requirements.
2
Place a small amount of adhesive (Loctite
®
435
™
)
in the cut-out on the datum clamp, ensuring none
of the adhesive wicks onto the scale surface.
Dispensing tips P-TL50-0209 are available.
Ensure the adhesive wicks
along the entire length of
the cut-out.
A-9585-0028
Datum clamp
IMPORTANT:
Allow 24 hours after scale application before fitting datum clamp.
1
Remove the backing paper from the datum clamp.
Place the datum clamp with the cut-out against the
scale at the chosen location.