Mitsubishi Electric MELSEC-L LD75D, User Manual

Page: 520 / 818

518
12.3
Functions for Compensating the Control
The sub functions for compensating the control include the "backlash compensation function", "electronic gear
function", "near pass function" and "Output timing selection of near pass control". Each function is executed by
parameter setting or program creation and writing.
12.3.1
Backlash compensation function
The "backlash compensation function" compensates the backlash amount in the mechanical system.
When the backlash compensation amount is set, an extra amount of pulses equivalent to the set backlash amount is
output every time the movement direction changes.
The details shown below explain about the "backlash compensation function".
• Control details
• Control precautions
• Setting method
(1) Control details
The following drawing shows the operation of the backlash compensation function.
(2) Control precautions
• The feed pulses of the backlash compensation amount are not added to the "[Md.20] Current feed value" or
"[Md.21] Machine feed value".
• Always carry out a machine OPR before starting the control when using the backlash compensation function
(when "[Pr.11] Backlash compensation amount" is set). The backlash in the mechanical system cannot be
correctly compensated if a machine OPR is not carried out.
• Set the No. of pulses output in one backlash compensation (value in which the "[Pr.11] Backlash
compensation amount" is divided by the "movement amount per pulse") to a value of 255 or lower. The error
"Backlash compensation amount error" (error code: 920) will occur if a value over 255 is set. (Depending on
the connected servo, tracking may not be possible if a large amount of pulses is output at once.)
• Backlash compensation, which includes the movement amount and "[Pr.11] Backlash compensation
amount", is output the moment at the moving direction changes.
• The backlash compensation function cannot be used for an axis where a stepping motor is connected. Set 0
(initial value) in "[Pr.11] Backlash compensation amount".
Pr.11 Backlash compensation amount
Worm gear
Workpiece
0
≤ ≤
Backlash compensation amount
255
Movement amount per pulse
(Omit values after the decimal point.)