Emerson P/N 400361-00 manual Index View with Timed Index Selected, Timed Index Profile Diagram

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.

		Max Velocity
Max Accel			Max Decel
Trapezoidal
Move			Index.ProfileLimited activates
				for this profile
Triangle
Move
	Time

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

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