Absolute Value System Usage Instructions

Overview

The absolute value encoder not only detects the position of the motor within one rotation, but also counts the number of rotations of the motor. The single rotation resolution is 8388608 (23 bits)/131072 (17 bits), and it can store 16 bit multi rotation data. The use of absolute value encoders can be divided into absolute position linear mode and absolute position rotation mode, which can be used in position, speed, and torque control modes. When the driver is powered off, the encoder backs up the data through the battery, and after power on, the driver calculates the mechanical absolute position through the absolute position of the encoder, without the need for repeated mechanical origin reset operations.

User setting P00-03 (absolute position detection selection). When the battery is first connected, Al.045 (encoder battery fault) occurs, and an absolute encoder reset operation needs to be performed through F-004.

Note: When modifying C-002 (motor rotation direction definition) or performing absolute encoder reset (F-004), the absolute position of the encoder will undergo a sudden change, resulting in a change in the mechanical absolute position reference. Therefore, mechanical origin reset operation is required. When using the internal origin reset function of the drive, the mechanical absolute position and encoder absolute position deviation will be automatically calculated and stored in the drive EEPROM after the origin reset is completed.

5.5.2 Relevant function code settings

1. Absolute value system settings

Select absolute position mode through P00-03.

Note: In absolute position mode, the system automatically detects whether the motor mode is an absolute value encoder motor. If not, Al.039 (absolute position mode product matching fault) will occur.

1. Encoder feedback data

The absolute value encoder provides feedback on the number of rotations and the position within one rotation,Incremental position mode no feedback number of rotations。

The absolute value encoder rotation data P13-34 is an unsigned number with a range of 0-65535, assuming the encoder resolution Rev:

The range of position P13-32 within one circle of the absolute value encoder is 0~Rev.

The absolute position of the absolute value encoder P13-50 * 232+P13-48 is calculated based on the feedback data P13-34, P13-32, and Rev .

When P13-34<32768, P13-50* 232 + P13-48 = P13-34 * Rev + P13-32

When P13-34 ≥ 32768, P13-50 * 232+P13-48=(P13-34-65536) * Rev+P13-32

1. Absolute value position linear mode

In absolute value linear mode, the mechanical position can be recorded by absolute value encoder when power off. After the user performs the origin regression function, the driver will record the point as the mechanical origin ,and record the offset between original point of the encoder and mechanical original point.

P_M = P_E – P_O

In absolute value linear mode, the multi turns data range of encoder is -32768~32767. If the number of forward turns is more than 32767 or the number of reverse turns is less than -32768, AL.044 (encoder multi turn counter overflow) fault will occur. This fault can be canceled by setting P0B-17.

1. Absolute value position rotation mode

The number of encoder pulses corresponding to one rotation can be set through P05-61/62 or P05-64/66, both of which can represent the number of encoder pulses corresponding to one rotation, with P05-64/66 having higher priority.

Assuming the encoder resolution R_E，the number of encoder pulses corresponding to one rotation R_M，when P05-64/66≠0，，when P05-64/66=0，

The parameters related to location are defined in the following table

• The relationship between the load single turn position command unit (P13-42) and the encoder unit (P13-44/46) is：

Note that the electronic gear ratio here is the position loop electronic gear ratio (P05-02/P05-04), not the mechanical gear ratio.

• The relationship between the mechanical absolute position (P13-38/40) and the rotational load single turn position (P13-44/46) is：

• The relationship between the number of load cycles and the position of a single load cycle is shown in the following figure. For every forward rotation of the load, the number of load cycles is increased by 1.

1. Absolute encoder reset operation

The reset operation of the encoder through F-004