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60 www.emersonct.com SM-EZMotion Module User Guide
the SM-EZ Motion module will automatically calculate the
necessary velocity, accel, and decel in order to achieve the
programmed distance in the specified time.
Note
A user program cannot compound into a Timed
Index, or compound out of a Timed Index.
All index types can be specified as a Timed Index, except
for Registration type indexes. This is because a
registration index does not have a specified distance or
absolute position. During a registration type index, the
registration sensor could activate at any time, and
therefore it is impossible to calculate the necessary
velocity, accel, and decel. If Registration type is selected,
then the Time checkbox will become disabled.
Based on the Distance entered (or Position for Absolute
indexes) and the Time value specified, the calculations
could result in extremely high Velocities, Accels, and
Decels. To avoid damage to mechanical parts, or
potentially dangerous situations, the user is allowed to
enter the Maximum Velocity, Acceleration, and
Deceleration used for the calculations. The results of the
firmware calculations will never exceed the maximum
values specified.
Figure 98 shows a screen capture in which the Timed
checkbox has been enabled. Notice how the parameters
that normally say Velocity, Acceleration, and Deceleration
have changed to say Max. Velocity, Max. Acceleration, and
Max. Deceleration. When the Time checkbox is enabled,
these parameters automatically become maximums for
use in the calculations.
Figure 98: Index View with Timed Index Selected
If the values for Max.Velocity, Max.Acceleration, and
Max.Deceleration are such that the distance cannot be
covered in the specified time, the Index.ProfileLimited flag
will activate when the index is initiated, indicating the index
cannot be performed as desired. The internal calculation
are performed only when the index is initiated, and
therefore is the only time the flag will activate. The
Index.ProfileLimited flag will remain active until cleared
using the Index.ResetProfileLimited assignment or
program instruction. In this situation, the index will still
operate, but the time will be extended. In other words, the
profile will be performed using the maximums values and
still cover the specified distance, but not in the specified
time.
The units for the Time parameter depend on the current
setting of the Time Base parameter.
If Time Base is set to "Realtime" (default), then the units for
the Time parameter are Seconds. The user can program
the index time with resolution of 0.001 Seconds (or
milliseconds). If Time Base is set to "Synchronized", the
units for the Time parameter are defined by the Master
Distance Units found on the Master Setup screen.
Doing a synchronized Timed Index means that the user
can specify the master distance in which the index should
be performed. This can be very useful in many
synchronized motion applications.
The internal calculations are designed to calculate a
triangular profile (all accel and decel). The ratio of
acceleration to deceleration will be the same ratio as Max.
Acceleration to Max. Deceleration parameters. For
example, if the deceleration is desired to be twice the
acceleration, a number twice the value of max acceleration
would be entered for maximum deceleration. Even in
trapezoidal moves, the same ratio of acceleration and
deceleration is maintained.
The calculations are based on the assumption that
Feedrate Override is set to 100%. If set to greater that
100%, the motor could run in excess of the specified Max.
Velocity.
Figure 99: Timed Index Profile Diagram
Enable Index PLS
This check box enables (when checked) or disables the
Index PLS function.
An Index PLS is similar to a global PLS (explained in the
PLS View section), but is incremental in nature. The Index
Triangle
Move
Trapezoidal
Move
Max Accel
Max Velocity
Max Decel
Index.ProfileLimited activates
for this profile
Time