12 - 12
MELSEC-Q
12 CONTROL SUB FUNCTIONS
[2] Precautions during control
(1) The feed pulses of the backlash compensation amount are not added to the
"Md.20 Current feed value" or "Md.21 Machi ne feed value".
(2) Always carry out a machine OPR before starting the c ontrol when using the
backlash compensation function (when " Pr.11 Backlash compensation
amount" is set). The backlash in the mechanic al system cannot be correctly
compensated if a machine OPR is not carried out.
(3) Set the No. of pulses output in one backlash c ompensation (value in which
the " Pr.11 Backlash compensation amount" is divided by the "movem ent
amount per pulse") to a value of 255 or lower. A "Backlash amount
compensation error (error code: 920)" will occur if a value ov er 255 is set.
(Depending on the connected servo, tracking m ay not be possible if a large
amount of pulses is output at once.)
Backlash compensation amount
0 ≤Movement amount per pulse ≤ 255
(Omit values after the decimal point.)
(4) Backlash compensation, which includes the m ovement amount and
"Pr.11 Backlash compensation amount", is output the moment at the
moving direction changes.
(5) Backlash compensation cannot be made when the s tepping motor is used.
[3] Setting the backlash compensation function
To use the "backlash compensation function", s et the "backlash compensation
amount" in the parameter shown in the following table, and write it to the QD75.
The set details are validated at the rising edg e (OFF ON) of the PLC READY
signal (Y0).
Setting item Setting
value Setting details Factory-set
initial value
Pr.11 Backlash
compensation
amount Set the backlash compensation amount. 0
Refer to Section 5.2 "List of parameters" for setting details.
REMARK
•Parameters are set for each axis.
•It is recommended that the parameters be set when ever possible with GX
Configurator-QP. Execution by sequence program uses many sequence programs
and devices. The execution becomes com plicated, and the scan times will
increase.