Section 1:
Introduction
Page 3
The Negate check box will force a positive entered value to be converted to a negative value before it is written to the
Ultra Drive. Likewise, when a negative value is read from the Ultra Drive it will be converted to a positive number
before it is displayed. The function would be used only when the variable must always be negative. For example, if
the motor must always turn in the negative direction, the operator would not have to remember to press the negative
key when entering a speed, distance, or position.
Scaling Example:
Since the drive returns the current motor velocity as a number of counts per second we can use
a scale value to convert the displayed value to revolutions per minute (RPM).
Scale Value = 1 / ( Counts per Revolution / 60 )
Scale Value = 1 / ( 8,000 / 60 )
Assume encoder producing 8,000 counts per revolution.
Scale Value = 1 / 133.33333
Scale Value = 0.0075 or 7.5e-3
This is the value into the Scale box.
If the 2800 has received a motor velocity value of 200,000.
RPM = Count Value Received x Scale Value
RPM = 200,000 x 0.0075
RPM = 1500
This is the value displayed by the 2800
If the operator enters 750, the 2800 will write the value 100,000 to the Drive..
Raw Value = Entered value / Scale Value
Raw Value = 750 / 0.0075
Raw Value = 100,000
This is the value written to the Ultra Drive.
Velocity Scaling:
convert from
Counts / Second
to
Revolutions / Minute
.
Scale value = 60 divided by encoder pulses per revolution.
Accel/Decel Scaling:
convert from
Counts / Second / Second
to
Revolutions / Second / Second
Scale value = one divided by encoder pulses per revolution.
PM2800U3K Revision 4
