Emerson FM-3 manual AbsolutePositionValid, Accelerating, AccelType

Parameter Descriptions

This section lists all programmable and feedback parameters available. The parameters are listed alphabetically by variable name (shown in italics below the on screen name) and give a description. Range is dynamic and depends on User Unit scaling. The units of the parameters are dynamic and depend on selected User Units.

Absolute Position Valid

AbsolutePositionValid

This source is activated when either the DefineHome destination is activated, or any home is successfully completed (sensor or marker found). This source is deactivated if the drive is rebooted, an encoder fault occurs, the drive is powered down, or a home is re-initiated.

Accelerating

Accelerating

This source is active when the FM-3 module is executing an acceleration ramp. A normal index consists of 3 segments: Accelerating, At Velocity, and Decelerating. The Accelerating source will be set (active) during this acceleration segment regardless of whether the motor is speeding up or slowing down. Therefore, this source can sometimes be active when the motor is decelerating. This could be true when compounding indexes together.

Acceleration Type

AccelType

This parameter is used to select the accel/decel type for all motion (homes, jogs and indexes). The “S-Curve” ramps offer the smoothest motion, but lead to higher peak accel/decel rates. “Linear” ramps have the lowest peak accel/decel rates but they are the least smooth ramp type. “5/8 S-Curve” ramps and “1/4 S-Curve” ramps use smoothing at the beginning and end of the ramp but have constant (linear) accel rates in the middle of their profiles. The “5/8 S- Curve” is less smooth than the “S-Curve” but smoother than the “1/4 S-Curve”. S-Curve accelerations are very useful on machines where product slip is a problem. They are also useful when smooth machine operation is critical. Linear ramps are useful in applications where low peak torque is critical. Below is a comparison of the 4 ramp types:

•S-Curve: Peak Accel = 2 x Average Accel

•5/8 S-Curve: Peak Accel = 1.4545 x Average Accel

•1/4 S-Curve: Peak Accel = 1.142857 x Average Accel

•Linear: Peak Accel = Average Accel

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