Aerotech UNIDEX 600 Series, Руководство пользователя

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U600 User’s Guide Parameters
Version 1.4
Aerotech, Inc.
C-29
C.2.60. MASTERLEN
This axis parameter is used only in the context of Camming (master/slave motion). It is
used to modulo the MASTERPOS axis parameter to avoid overruns of the 32-bit
MASTERPOS value. It is set in counts, for the slave axis. It is used only when the master
is a rotary axis, and the master axis will be cycled through multiple revolutions while
synchronized.
When cycling a rotary axis through multiple revolutions, the controller modulo’s the
position to zero when it reaches 360 degrees. The MASTERLEN axis parameter serves
the same purpose for the MASTERPOS axis parameter. The MASTERLEN axis
parameter must be set to the number of counts per 360 degrees, to avoid overruns of the
32-bit counter. For example, if axis A is a rotary master axis with 1000 counts/deg
mastering the X axis, then set MASTERLEN.X=360000.
This value must be zero, or an integer multiple of the range of master positions
spanned by the cam table. Otherwise, when it modulo’s the position, it will
incorrectly index into the cam table and violently jerk the slave axes.
C.2.61. MASTERPOS
This axis parameter is only used for Camming (master/slave motion). This axis parameter
is set for the slave axis. It is the position of the master axis in counts, as seen by the slave.
It is the actual value the slave axis uses, in conjunction with the cam table, to find its slave
position. Usually, it is equal to position of the master, and can be ignored. However, there
are two situations where they may vary:
1. If the master axis has a higher task axis index than the slave (see Section
C.2.61.1., below)
2. Prior to Synchronization of the axis (see description below).
If a slave axis is in a non-zero SYNC mode, then the MASTERPOS value of the slave
axis is “read-only”, because it is being continuously updated by the controller, which is
integrating the master axis velocity. However, if a slave axis is in sync mode 0, then the
MASTERPOS value of the slave is read/write, and does not track the master position.
Therefore, when a slave is synced up, changes in position of the master axis are tracked
accurately, but the initial master position value is undetermined. For example, suppose
after power-up, a camming action occurs which brings the master to 1000 counts. Then
suppose camming is disabled, and the master axis is moved back to 0 counts. During this
latter move MASTERPOS is not updated, so it still reads 1000 counts, even though the
actual position of the master axis is 0 counts. As explained above, MASTERPOS is not
set on syncing up, so MASTERPOS now has a 1000 count offset. If this is done
repeatedly, it can eventually lead to overruns of the 32-bit MASTERPOS value, which
leads to violent jerks of the slave axis. Furthermore, it can lead to erroneous motion when
syncing in mode 2.
Therefore the following line is always recommended prior to synchronization.
MASTERPOS.X = POS.Y ; where X is the slave, Y is the master
Or, if you are tracking Position command on the master:
WARNING