Technical information

84
230V FX Series Positioning Drive Reference Manual
Velocity User Units
To make the display data meaningful, you may convert the velocity units on your machine to
the units used by the FX drive. Since it is possible to use an FX drive on a wide variety of
applications, velocity units other than RPM can be set up. Three characters are available for
velocity units (i.e., IPS, I/S, FPM, and F/M).
Velocity Scaling
In order to set the velocity units correctly, they must be scaled against the maximum velocity
of your motor and drive. The range of velocity scaling is 1 to 65,535 (ignoring the decimal
point) and use the maximum number of digits for maximum resolution.
The steps below are used to calculate velocity user units. For the following examples,
calculate your system using a FX-455/DXE-455.
1. Calculate a motor speed of 3000 RPM results in 600 in/sec. Enter 600.00 IPS.
2. Calculate a motor speed in 360 deg/sec. Enter 360.00 DPS Velocity changes in .01 deg/
sec increments (or nearest equivalent to .1 RPM).
3. Calculate a motor speed in 34.5254 ft/sec. Enter 34.525 FPS. (Maximum scaling entry
equals 65535.)
Maximum velocity resolution will never get finer than .1 RPM.
For example, in a lead screw application, if the motor’s top speed is 3000 RPM and the screw
pitch is 5 RPI (revolutions per inch), the top speed of the lead screw would be:
3000 RPM/5 RPI = 600 IPM (inches per minute)
or
600 IPM/60 seconds = 10 IPS (inches per second)
Accel/Decel Shape
This option also allows you to choose either linear ramps or mod-sine ramps for acceleration
and deceleration. Mod-sine ramps enter acceleration more smoothly, enter and exit the
constant velocity part of the index more smoothly and reduce index maximum velocity about
20 percent. Mod-sine ramps require approximately 40 percent more peak current during
acceleration and deceleration. This current is only required during the middle portion of the
ramp.