ETS-Lindgren 2188 Turntable - Manual (Page 26)

Model 2188 Turntable
©ETS-Lindgren—January, 2006
Rev. B—P#399771
26
5. Record the reading of the display, ignoring the decimal point
(i.e. 360.0 would be 3600). This is the encoder calibration
value.
NOTE: If the value is below 3600, the resolution of the encoder
is low and consequently the controller will not provide 0.1-
degree resolution, even though the display shows that digit. If
the value has gone past 9999, the encoder has too many counts
per meter and the controller cannot correct for it. In this case,
contact ETS-Lindgren for assistance.
6. Enter the encoder calibration value and reset the limits and
position information.
7. Test the turntable by moving it a complete revolution and
comparing the alignment marks. It may be necessary to adjust
the encoder calibration value up or down slightly depending on
the result.
NOTE: When scanning between limits, it is not uncommon to
have a small discrepancy between the absolute position of the
table and the display on the controller. This is because
reversing the direction of rotation reverses any gear play
between the encoder and the table top, allowing that play to be
visible in the positioning accuracy.
5.3.2. Turntable Calibration Example
• The table is set at the “0” degree position. A piece of tape is
placed on the edge of the turntable to line up with the edge
of the gearbox cover. The table is stopped when the tape
travels exactly 360 degrees around. The display on the
controller now reads 356.3 degrees, which is recorded.
• The table is rotated CCW back to zero. The parameter
button is set on the “C” setting. The “C” digits display 3430.
A new “C” setting is now calculated:
• New “C” = (356.3 divided into 360) times 3430 = 3395
(rounded off).
• The decrement the C parameter to 3395 and “ENTER” is
pressed. The “current position” button is pressed to get back
to operation mode.