Mitsubishi Electric MELSEC iQ-R RD75P4, User Manual

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12 DATA USED FOR POSITIONING CONTROL
12.3 Basic Setting
[Pr.7] Bias speed at start
Set Minimum speed at start for Bias speed at start. Set Bias speed at start to allow the motor to start smoothly especially
when a stepping motor is used. (A stepping motor does not start smoothly if a low rotation speed is instructed at the start.)
The specified Bias speed at start will be valid during the following operations:
• Positioning operation
• OPR
• JOG operation
Set a value equal to or less than the value set in [Pr.8] Speed limit value.
■
Buffer memory address
The following table shows the buffer memory address of this area.
■
Setting range
The setting range depends on the setting of [Pr.1] Unit setting.
*1 When this buffer memory area is set with programs, a calculation is performed in the RD75 to convert a setting value to the value in
each unit. For setting this buffer memory area, take the value after the unit conversion into consideration.
■
Default value
The default value is 0 for all the axes.
■ Precautions for using a stepping motor
• For the system that uses a stepping motor, executing the S-curve acceleration/deceleration may cause step out. Before
using the S-curve acceleration/deceleration, check that step out does not occur.
• In the system that uses a stepping motor, the circular interpolation control and 3-axis helical interpolation control cannot be
performed. Although setting the bias speed at start is required by the characteristics of the stepping motor, the setting of the
bias speed at start is disabled for circular interpolation control or 3-axis helical interpolation control. Use a servomotor for
both two axes when the circular interpolation control or 3-axis helical interpolation control is performed.
Buffer memory name Axis 1 Axis 2 Axis 3 Axis 4
[Pr.7] Bias speed at start 6 156 306 456
7 157 307 457
Setting of [Pr.1] Unit setting Setting value with engineering tools Setting value with programs
*1
0: mm 0 to 20000000.00 (mm/min) 0 to 2000000000 (

10
-2
mm/min)
1: inch 0 to 2000000.000 (inch/min) 0 to 2000000000 (

10
-3
inches/min)
2: degree 0 to 3000000.000 (degree/min) 0 to 3000000000 (

10
-3
degrees/min)
3: pulse 0 to 5000000 (pulse/s) 0 to 5000000 (pulse/s)
t t
Speed
When the bias speed at start is 0
Speed
The speed is accelerated from
the bias speed at start
When the bias speed at start is other than 0
Command
speed Command
speed