4 Operation
4.7.6 Multiturn Limit Setting
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4.7.6
Multiturn Limit Setting
The multiturn limit setting is used in position control applications for a turntable or other rotating device. For
example, consider a machine that moves the turntable in the following diagram in only one direction.
Because the turntable moves in only one direction, the upper limit for revolutions that can be counted by an
absolute encoder will eventually be exceeded. The multiturn limit (rotational serial data limit) is used in cases
like this to prevent fractions from being produced by the integral ratio of the motor revolutions and turntable
revolutions.
For a machine with a gear ratio of n:m, as shown above, the value of m minus 1 will be the setting for the mul-
titurn limit setting (Pn205).
Multiturn limit setting (Pn205) = m-1
The case in which the relationship between the turntable revolutions and motor revolutions is m = 100 and n =
3 is shown in the following graph.
Pn205 is set to 99.
Pn205 = 100
−
1 = 99
Note: This parameter is valid when the absolute encoder is used.
The range of the data will vary when this parameter is set to anything other than the factory setting.
1. When the motor rotates in the reverse direction with the rotational serial data at 0, the rotational serial data
will change to the setting in Pn205.
2. When the motor rotates in the forward direction with the rotational serial data at the Pn205 setting, the rota-
tional serial data will change to 0.
Set Pn205 to the following value: Desired rotation serial data -1.
When the set value in Pn205 is changed, a multiturn limit disagreement alarm (A.CC0) will be displayed
because the multiturn limit value in the encoder will be different. For the procedure to change the multiturn
Pn205
Multiturn Limit Setting
Classification
Setting Range
Setting Unit
Factory Setting
When Enabled
0 to 65535
1 Rev
65535
After restart
Setup
Turntable
Gear
Servomotor
0
1
2
3
4
5
6
7
8
9
Motor rotations
100 200 300 0
100
50
Rotational
serial data
Turntable rotations
Set value of Pn205 = 99
Turntable
rotations
Rotational
serial data
Speed
Position
Torque
