Parameter Descriptions - Emerson Control Techniques FM-4 Reference Manual

Programming module

Table of Contents

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

This source is active when the FM-4 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

Acceleration Decimal Places

AccelUnits.Decimal

This parameter is the decimal point location for all real-time accel./decel. ramps.

Acceleration Time Scale

AccelUnits.TimeScale

This parameter is the time units for accel./decel. ramps. Possible selections are milliseconds or seconds.

At Velocity

AtVel

This source is active when the FM-4 module is executing a constant velocity motion segment. One example would be during

an index. The source would activate after the motor has finished accelerating up to speed and before the motor begins to

decelerate to a stop. A normal index consists of 3 segments: Accelerating, At Velocity, and Decelerating. This source is active

during the At Velocity segment, and is activated based on the commanded velocity, not the feedback velocity. During

synchronized motion, AtVel can be active without actual motor movement.

FM-4 Programming Module Reference Manual