Position lock tolerance, Output limit – Rockwell Automation 1784-PM16SE SoftLogix Motion Card Setup and Configuration Manual User Manual
Page 158
Publication 1784-UM003A-EN-P – June 2003
150 Naming & Configuring Your Motion Axis
Note: This value is set to twice the following error at maximum speed
based on the measured response of the axis, during the autotuning
process. In most applications, this value provides reasonable protection
in case of an axis fault or stall condition without nuisance faults during
normal operation. If you need to change the calculated position error
tolerance value, the recommended setting is 150% to 200% of the
position error while the axis is running at its maximum speed.
Position Lock Tolerance
Specifies the maximum position error the servo module accepts in order to
indicate the Position Lock status bit is set. This is useful in determining when
the desired end position is reached for position moves. This value is
interpreted as a +/- quantity.
For example, specifying a lock tolerance of 0.01 provides a minimum
positioning accuracy of +/- 0.01 position units, as shown here:
Output Limit
Provides a method of limiting the maximum servo output voltage of a physical
axis to a specified level. The servo output for the axis as a function of position
servo error, both with and without servo output limiting, is shown below.
The servo output limit may be used as a software current or torque limit if you
are using a servo drive in torque loop mode. The percentage of the drive’s
maximum current that the servo controller ever commands is equal to the
specified servo output limit. For example, if the drive is capable of 30 Amps of
current for a 10 Volt input, setting the servo output limit to 5V limits the
maximum drive current to 15 Amps.
The servo output limit may also be used if the drive cannot accept the full ±10
Volt range of the servo output. In this case, the servo output limit value
effectively limits the maximum command sent to the amplifier. For example, if
the drive can only accept command signals up to ±7.5 Volts, set the servo
output limit value to 7.5 volts.