12CONTROL SUB FUNCTIONS

[2]Precautions during control

MELSEC-Q

(1) The feed pulses of the backlash compensation amount are not added to the

"

Md.20

Current feed value" or "

Md.21

Machine feed value".

(2) 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.

(3) 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. A "Backlash amount compensation 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.)

0

Backlash compensation amount

255

Movement amount per pulse

 

 

 

(Omit values after the decimal point.)

(4) Backlash compensation, which includes the movement amount and

"

Pr.11

Backlash compensation amount", is output the moment at the

moving direction changes.

(5)Backlash compensation cannot be made when the stepping motor is used.

[3]Setting the backlash compensation function

To use the "backlash compensation function", set 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 edge (OFF ON) of the PLC READY signal (Y0).

 

Setting item

Setting

Setting details

Factory-set

 

value

initial value

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Backlash

 

 

 

 

Pr.11

 

compensation

 

Set the backlash compensation amount.

0

 

 

 

amount

 

 

 

 

 

 

 

 

 

 

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 whenever possible with GX Configurator-QP. Execution by sequence program uses many sequence programs and devices. The execution becomes complicated, and the scan times will increase.

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Mitsubishi Electronics QD75P, QD75D user manual Setting the backlash compensation function, Current feed value or, 255