Mitsubishi Electric MELSEC iQ-R RD78G4 - Page 143

5 ADVANCED SYNCHRONOUS CONTROL INITIAL POSITION
5.1 Synchronous Control Initial Position
141
5
Position value per cycle after main/auxiliary shaft gear at synchronous control start
The position value per cycle after main shaft gear/position value per cycle after auxiliary shaft gear is restored as follows
according to the main input axis/auxiliary shaft operation executed before starting synchronous control.
*1 When "[Pr.300] Servo input axis type" is either "1: Command position value" or "2: Actual position value", and when "[Pr.21] Command
position value during speed control" is "2: Clear command position value to zero" only.
*2 When the unit setting of the servo input axis is set to degree, the servo input axis value is rounded within the range of 0 to 359.99999°
and the difference from the position value of the servo input axis under the last synchronous control is restored as the amount of change
as described in the following restoration method 2). Therefore, if positioning is performed beyond 360degrees on the servo input axis,
the position value per cycle after main shaft gear / position value per cycle after auxiliary shaft gear may not be correctly restored. In
such a case, use "[Pr.460] Setting method of position value per cycle after main shaft gear" / "[Pr.461] Setting method of position value
per cycle after auxiliary shaft gear" as "0: Previous value" or "1: Initial setting value of position value per cycle after main shaft gear /
Initial setting value of position value per cycle after auxiliary shaft gear".
*3 If the main input axis is moved beyond ±2147483647 (input axis unit) from the last synchronous control before synchronous control is
started, the correct amount of change cannot be calculated. In such a case, set "[Pr.460] Setting method of position value per cycle after
main shaft gear" / "[Pr.461] Setting method of position value per cycle after auxiliary shaft gear" to "0: Previous value" or "1: Initial setting
value of position value per cycle after main shaft gear / Initial setting value of position value per cycle after auxiliary shaft gear".
Restoration method 1): The new value of the position value per cycle after main shaft gear/position value per cycle after
auxiliary shaft gear is calculated based on the position value after composite main shaft gear/auxiliary shaft current value.
[Main shaft]
Position value per cycle after main shaft gear = Main shaft gear ratio  Position value after composite main shaft gear
[Auxiliary shaft]
Position value per cycle after auxiliary shaft gear = Auxiliary shaft gear ratio  Auxiliary shaft current value
Restoration method 2): The movement amount from the last synchronous control session is reflected to the position value per
cycle after main shaft gear/position value per cycle after auxiliary shaft gear.
[Main shaft]
Position value per cycle after main shaft gear =
Position value per cycle after main shaft gear at the last synchronous control session + Main shaft gear ratio  Amount of
change of position value after composite main shaft gear from the last synchronous control session
[Auxiliary shaft]
Position value per cycle after auxiliary shaft gear =
Position value per cycle after auxiliary shaft gear at the last synchronous control session + Auxiliary shaft gear ratio  Amount
of change of auxiliary shaft current value from the last synchronous control session
Operation of main
input axis/auxiliary
shaft
(Before synchronous
control start)
Servo input axis Command
generation axis
Synchronous encoder axis
Absolute
position
detection system
valid
Absolute
position
detection system
invalid
Synchronous
encoder via
servo
amplifier
(incremental
system)
Synchronous
encoder via
servo
amplifier
(absolute
position
system)
Synchronous
encoder via
CPU
Home position return Restoration method 1) 
Current value change Restoration method 1) Restoration method 1) Restoration method 1)
Speed control
*1
Restoration method 1) Restoration method 1) 
Fixed-pitch feed control Restoration method 1) 
Speed-position switching
control
*1
Restoration method 1) Restoration method 1) 
Position-speed switching
control
*1
Restoration method 1) 
Connection to servo
amplifier
Restoration method
2)
*2*3
Restoration method
1)

Connection to
synchronous encoder
Restoration
method 1)
Restoration
method 2)
*3
Restoration
method 2)
Others Restoration method 2)
*3
Restoration method
2)
*3
Restoration method 2)
*3