Emerson FM-3 - Manual (Page 65)

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Setting Up Parameters
FeedRate Decel/Accel
The FeedRate Decel/Accel parameter specifies the ramp used when velocity changes due to
a change in the FeedRate Override value. The units of FeedRate Decel/Accel are Seconds/
100% of Feed Rate. Therefore, the user must specify the amount of time (in seconds) to
accelerate or decelerate 100% of FeedRate.
Examples:
FeedRate Override is set to 100% (default). The user wishes to slow down motion to 50% of
programmed velocity. If FeedRate Decel/Accel is set to 1 Sec/100%, when the FeedRate
Override parameter is changed to 50%, it will take 0.5 seconds to decelerate to 50% velocity.
A user wishes to accelerate from 100% programmed velocity to 175% in 0.5 Seconds.
Therefore, the value they need to enter for FeedRate Decel/Accel is calculated as follows:
Online Tab (not shown)
If online, this view will show the limits group and the velocity group.
Velocity Group
Velocity Command
The Velocity Command is the actual command generated by the FM-3 module to the motor
in user units.
Velocity Feedback
This parameter is the actual feedback motor velocity in user units.
Decel/Accel Time = FeedRate Decel/Accel * % Change in Feedrate
= (1 Sec/100%) * (100% - 50%)
= 0.5 Seconds
FeedRate Decel/Accel = Decel Time/ % Change in Feedrate
= (0.5 Sec) / (175% - 100%)
= 0.5 Sec / 75%
= (0.5 Sec) / (100% * 75%)
= 0.66 Sec / 100%