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System integration
For systems where the HS20 is indirectly connected to the motion controller via an RCU compensa-
tor, please refer to The RCU10 quadrature compensation unit - Installation and User's Guide.
Before closing the feedback loop using signals from HS20 it is essential that the checks
defined below are carried out for HS20 each axis in turn. The objective of these tests is to
confirm that the following:
- Motion of the appropriate axis drive is stopped immediately an HS20 signals an error or if its
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power supply fails, and that the controller display correctly indicates the source of the error.
-The direction sense and resolution settings on each HS20, RCU and the associated machine
axis have all been set correctly.
- The controller logic has been correctly configured to allow each HS20 to be reset (as
required to clear an error), and to handle the laser's warm- up period (during which the laser
will indicate an unstable error).
Having followed through the manual the following stages should now have been completed.
• HS20 is mounted on the machine,
• The laser beam is aligned,
• The HS20 is electrically connected to the controller
• An axis reference mark signal is connected to the RCU.
• The RCU must have been configured in accordance the RCU10 manual (M-9904-1122)
• Although the electrical connections have been made, the associated machine axis drives
have NOT yet been enabled (machine is in E-stop).
The following steps prepare the system for switch over to HS20 feedback
Reset input signal
The HS20 laser head also requires one control line input. The function of this line is to reset the HS20
laser head in the event of an error. This line is active low and must be held at 24V (high) during normal
operation.
Operation of system on power-up
Following an initial power up, the HS20 laser heads take a period of between 10 and 15 minutes to
stabilise. During this period of laser instability the /UNSTABLE status line is asserted and the digital
quadrature lines are tristated.
For this reason it is advisable that the HS20 laser heads are powered from a supply that remains on
even when the machine controller is powered-down. This will avoid a 15 minute delay each time that
the machine control is powered-up.
Note: Ideally each HS20 laser head will have its own independent machine generated /RESET line. Once
the HS20 laser heads become stable, indicated by the /UNSTABLE line being pulled high, the quadrature
lines and HS20 status lines have the tristate (high impedance) state removed and are activated.
WARNING: The HS20 laser encoder continuously checks for any internal errors that may
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cause invalid position feedback signals, and signals a fault by tristating the digital and
analogue quadrature lines. In the case of closed loop motion systems, for safe operation
this must be monitored. If the tristated quad is asserted, the position feedback signals may
be incorrect and the axis of motion must be stopped.
NB: In the event of power loss from the HS20 tristated quad become inactive and the
axis of motion must be stopped.
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