SECTION 2 - RGH20F/REF system
REF interface features
Self-tuning active correction
The REF interface actively corrects for input signal imperfections to improve system accuracy.
Corrections are made for the following:
Automatic Offset Control (AOC)
– adjusts offset independently for the sine and cosine signals.
Automatic Gain Control (AGC)
– ensures consistent 1 Vpp signal amplitude.
Automatic Balance Control (ABC)
– adjusts the gain to equalise the sine and cosine signals.
These correction mechanisms operate over the full working speed range of the readhead.
System calibration
Calibration is an essential operation that optimises the gain, balance and offset of the analogue input signals
in the REF interface. These values are stored for initial use at start-up. Before system calibration, install the
readhead to maximise the signal strength around the full ring travel as described in ‘Readhead mounting
and alignment’ section.
Incremental signal calibration
Ensure Automatic Gain Control (AGC) is switched off (CAL/AGC LED on interface is off)
before beginning calibration.
Press and release the CALIBRATE button on the interface.
The CAL/AGC LED will now fl ash slowly.
Rotate the ring at slow speed until the CAL/AGC LED stops fl ashing.
The calibration cycle is now complete.
If the calibration fails the CAL/AGC LED will fl ash quickly instead of switching off. In this case manually
exit the calibration routine, restore factory defaults and repeat the calibration procedure.
Calibration routine manual exit
To exit the calibration routine at any time press the CALIBRATE button.
The CAL/AGC LED will stop fl ashing and values will not be stored.
To complete the calibration procedure restore factory defaults and repeat the calibration procedure.
Restoring factory defaults
When re-installing the system, or in the case of calibration failure, the factory defaults should be restored.
To restore factory defaults.
Switch the system off.
Press and hold the CALIBRATE button whist switching on the power.
Release the CALIBRATE button.
Repeat the ‘Readhead mounting and alignment’ procedure and re-calibrate the system.
NOTE:
The system must be re-calibrated after restoring factory defaults.
Switching Automatic Gain Control on or off
AGC can be switched on via the REF interface CALIBRATE button.
Press and hold the CALIBRATE button on the interface for >3 seconds to switch AGC on or off.
The CAL /AGC LED on the interface will be illuminated when AGC is active.
NOTE:
The system must be calibrated before switching AGC on.
*NOTE:
Reference mark fl ashes only occur up to 100 mm/s traverse speed
Alarms can also be output for the following conditions, depending on REF alarm option:
Readhead speed in excess of specifi cation
Automatic Offset Control excessive
LED indicators
Purple
Blue
Green
Orange
Red
Purple/blank -fl ashing
Red/blank -fl ashing
Red fl ash when traversing
reference mark
*
Orange fl ash when traversing
reference mark
*
Blank fl ash when traversing
reference mark
*
On
Off
Slow fl ashing
Fast fl ashing
Alarm
output
No
No
No
No
No
Yes
Yes
No
No
No
No
No
No
No
Normal set-up; signal level
110% to 135%
Optimum set-up; signal level
90% to 110%
Normal set-up; signal level
70% to 90%
Acceptable set-up; signal level
50% to 70%
Poor set-up; signal may be too
low for reliable operation;
signal level <50%
Over signal; signal level
>135%; system in error
Poor set-up; signal level
<20%; system in error
Normal phasing of
reference mark
Acceptable phasing of
reference mark
Poor phasing of reference
mark; recalibrate
Automatic Gain Control - On
Automatic Gain Control - Off
Calibrating system
Calibration failed
Indication
Status
Set-up
CAL/AGC
REF LED