Section 4 - Alignment & Calibration
4-11
The xx.x equals the measurement you typed in above. If you type N, the system redisplays the
second message and you should retype the distance you measured. If you type Y, the system
displays the following:
Update Driver INI-File [Y/N] ?
6.
Type Y<Enter>.
The SQDRIVER program then reads the calibration parameters from the TZ microprocessor and
prompts
set_table_calibration=499,3490,500,3494
calibrate_position=10,1000,1000,819,50000,500,500,3494
pos_limit_position=182784
neg_limit_position=0
Update Driver INI-File [Y/N] ?
The four values for
set_table_calibration
are, respectively, the left pedestal lower and upper
encoder limits and the right pedestal lower and upper encoder limits. The two lower limits should
be
close
to each other, as should the two upper limits. The eight
calibrate_position
fields are:
1)
10
(Tolerance). The
±
position tolerance, in encoder ticks, for absolute moves.
Although the TZ microprocessor does its own absolute moves, not the AT device
driver, this field is used by state machine programs to determine whether the TZ
position is within tolerance and should be ten (10).
2,3)
1000,1000
(NumberOfSteps,StepDistance). The number of motors steps
corresponding to the step distance in microns. These two fields are only used for
stepping motors, not for the DC table motors, and should always be 1000,1000.
4,5)
819,50000
(NumberOfTicks,TickDistance). The number of encoder ticks
corresponding to the tick distance in microns. The table encoder calibration is fixed
and should always be 819 encoder counts per 50,000 microns.
6)
500
(EncoderOffset). The value subtracted from the encoder readback to set the origin
of motion. The origin of TZ motion is the lower right pedestal, so this field should be
the same as the third field in the
set_table_calibration
line (above).
7,8)
500,3494
(NegLimit,PosLimit). The encoder readings for the negative (downward) and
positive (upward) mechanical stops. In normal operation, the TZ microprocessor uses
the right pedestal readings for closed loop control so these two fields should be the
same as the last two fields in the
set_table_calibration
line (above).
The
pos_limit_position
and the
neg_limit_position
are the limits of motion, in microns, in
the positive and negative direction
Note:
The
PosLimitOffset
and
NegLimitOffset
entries in the
[TzMotor]
section of the
hardware.ini
file determine the motion limits relative to the mechanical stops. If these
entries are not present, or are zero, the motion limits are set to the mechanical limits, as in
the above example.
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