4 Operation4.7.6 Multiturn Limit Setting4-484.7.6 Multiturn Limit SettingThe multiturn limit setting is used in position control applications for a turntable or other rotating device. Forexample, 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 anabsolute encoder will eventually be exceeded. The multiturn limit (rotational serial data limit) is used in caseslike this to prevent fractions from being produced by the integral ratio of the motor revolutions and turntablerevolutions.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-1The 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 = 99Note: 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 datawill 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 displayedbecause the multiturn limit value in the encoder will be different. For the procedure to change the multiturnPn205Multiturn Limit Setting ClassificationSetting Range Setting Unit Factory Setting When Enabled0 to 65535 1 Rev 65535 After restart SetupTurntableGearServomotor0123456789Motor rotations100 200 300 010050Rotationalserial dataTurntable rotationsSet value of Pn205 = 99TurntablerotationsRotationalserial dataSpeed Position Torque
